diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-31 19:25:25 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-31 19:25:25 -0800 |
| commit | 255442c93843f52b6891b21d0b485bf2c97f93c3 (patch) | |
| tree | 8fd1daa752dbfa4721f64421ab7d4e695605d9f7 /Documentation | |
| parent | d76e0a050e0f5e7c00e6d334f758178bbc16eb98 (diff) | |
| parent | ae17a87dd7c79fa742ef5dcf06d1095eec4e1925 (diff) | |
Merge tag 'docs-4.16' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"Documentation updates for 4.16.
New stuff includes refcount_t documentation, errseq documentation,
kernel-doc support for nested structure definitions, the removal of
lots of crufty kernel-doc support for unused formats, SPDX tag
documentation, the beginnings of a manual for subsystem maintainers,
and lots of fixes and updates.
As usual, some of the changesets reach outside of Documentation/ to
effect kerneldoc comment fixes. It also adds the new LICENSES
directory, of which Thomas promises I do not need to be the
maintainer"
* tag 'docs-4.16' of git://git.lwn.net/linux: (65 commits)
linux-next: docs-rst: Fix typos in kfigure.py
linux-next: DOC: HWPOISON: Fix path to debugfs in hwpoison.txt
Documentation: Fix misconversion of #if
docs: add index entry for networking/msg_zerocopy
Documentation: security/credentials.rst: explain need to sort group_list
LICENSES: Add MPL-1.1 license
LICENSES: Add the GPL 1.0 license
LICENSES: Add Linux syscall note exception
LICENSES: Add the MIT license
LICENSES: Add the BSD-3-clause "Clear" license
LICENSES: Add the BSD 3-clause "New" or "Revised" License
LICENSES: Add the BSD 2-clause "Simplified" license
LICENSES: Add the LGPL-2.1 license
LICENSES: Add the LGPL 2.0 license
LICENSES: Add the GPL 2.0 license
Documentation: Add license-rules.rst to describe how to properly identify file licenses
scripts: kernel_doc: better handle show warnings logic
fs/*/Kconfig: drop links to 404-compliant http://acl.bestbits.at
doc: md: Fix a file name to md-fault.c in fault-injection.txt
errseq: Add to documentation tree
...
Diffstat (limited to 'Documentation')
37 files changed, 1376 insertions, 614 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index 3bec49c33bbb..7f3a0728ccf2 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -228,8 +228,6 @@ isdn/ - directory with info on the Linux ISDN support, and supported cards. kbuild/ - directory with info about the kernel build process. -kernel-doc-nano-HOWTO.txt - - outdated info about kernel-doc documentation. kdump/ - directory with mini HowTo on getting the crash dump code to work. doc-guide/ @@ -346,8 +344,6 @@ prctl/ - directory with info on the priveledge control subsystem preempt-locking.txt - info on locking under a preemptive kernel. -printk-formats.txt - - how to get printk format specifiers right process/ - how to work with the mainline kernel development process. pps/ diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index b98048b56ada..dc63e5bddf78 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2538,6 +2538,9 @@ This is useful when you use a panic=... timeout and need the box quickly up again. + These settings can be accessed at runtime via + the nmi_watchdog and hardlockup_panic sysctls. + netpoll.carrier_timeout= [NET] Specifies amount of time (in seconds) that netpoll should wait for a carrier. By default netpoll diff --git a/Documentation/admin-guide/mono.rst b/Documentation/admin-guide/mono.rst index cdddc099af64..59e6d59f0ed9 100644 --- a/Documentation/admin-guide/mono.rst +++ b/Documentation/admin-guide/mono.rst @@ -9,14 +9,14 @@ This will allow you to execute Mono-based .NET binaries just like any other program after you have done the following: 1) You MUST FIRST install the Mono CLR support, either by downloading - a binary package, a source tarball or by installing from CVS. Binary + a binary package, a source tarball or by installing from Git. Binary packages for several distributions can be found at: - http://go-mono.com/download.html + http://www.mono-project.com/download/ Instructions for compiling Mono can be found at: - http://www.go-mono.com/compiling.html + http://www.mono-project.com/docs/compiling-mono/linux/ Once the Mono CLR support has been installed, just check that ``/usr/bin/mono`` (which could be located elsewhere, for example diff --git a/Documentation/conf.py b/Documentation/conf.py index 63857d33778c..62ac5a9f3a9f 100644 --- a/Documentation/conf.py +++ b/Documentation/conf.py @@ -88,7 +88,6 @@ finally: if makefile_version and makefile_patchlevel: version = release = makefile_version + '.' + makefile_patchlevel else: - sys.stderr.write('Warning: Could not extract kernel version\n') version = release = "unknown version" # The language for content autogenerated by Sphinx. Refer to documentation diff --git a/Documentation/errseq.rst b/Documentation/core-api/errseq.rst index 4c29bd5afbc5..ff332e272405 100644 --- a/Documentation/errseq.rst +++ b/Documentation/core-api/errseq.rst @@ -1,5 +1,7 @@ +===================== The errseq_t datatype ===================== + An errseq_t is a way of recording errors in one place, and allowing any number of "subscribers" to tell whether it has changed since a previous point where it was sampled. @@ -21,12 +23,13 @@ a flag to tell whether the value has been sampled since a new value was recorded. That allows us to avoid bumping the counter if no one has sampled it since the last time an error was recorded. -Thus we end up with a value that looks something like this:: +Thus we end up with a value that looks something like this: - bit: 31..13 12 11..0 - +-----------------+----+----------------+ - | counter | SF | errno | - +-----------------+----+----------------+ ++--------------------------------------+----+------------------------+ +| 31..13 | 12 | 11..0 | ++--------------------------------------+----+------------------------+ +| counter | SF | errno | ++--------------------------------------+----+------------------------+ The general idea is for "watchers" to sample an errseq_t value and keep it as a running cursor. That value can later be used to tell whether @@ -42,6 +45,7 @@ has ever been an error set since it was first initialized. API usage ========= + Let me tell you a story about a worker drone. Now, he's a good worker overall, but the company is a little...management heavy. He has to report to 77 supervisors today, and tomorrow the "big boss" is coming in @@ -125,6 +129,7 @@ not usable by anyone else. Serializing errseq_t cursor updates =================================== + Note that the errseq_t API does not protect the errseq_t cursor during a check_and_advance_operation. Only the canonical error code is handled atomically. In a situation where more than one task might be using the @@ -147,3 +152,8 @@ errseq_check_and_advance after taking the lock. e.g.:: That avoids the spinlock in the common case where nothing has changed since the last time it was checked. + +Functions +========= + +.. kernel-doc:: lib/errseq.c diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst index d5bbe035316d..1b1fd01990b5 100644 --- a/Documentation/core-api/index.rst +++ b/Documentation/core-api/index.rst @@ -14,6 +14,7 @@ Core utilities kernel-api assoc_array atomic_ops + refcount-vs-atomic cpu_hotplug local_ops workqueue @@ -21,6 +22,8 @@ Core utilities flexible-arrays librs genalloc + errseq + printk-formats Interfaces for kernel debugging =============================== diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst index 2d9da6c40a4d..e7fadf02c511 100644 --- a/Documentation/core-api/kernel-api.rst +++ b/Documentation/core-api/kernel-api.rst @@ -139,6 +139,21 @@ Division Functions .. kernel-doc:: lib/gcd.c :export: +Sorting +------- + +.. kernel-doc:: lib/sort.c + :export: + +.. kernel-doc:: lib/list_sort.c + :export: + +UUID/GUID +--------- + +.. kernel-doc:: lib/uuid.c + :export: + Memory Management in Linux ========================== diff --git a/Documentation/printk-formats.txt b/Documentation/core-api/printk-formats.rst index aa0a776c817a..258b46435320 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/core-api/printk-formats.rst @@ -5,6 +5,7 @@ How to get printk format specifiers right :Author: Randy Dunlap <rdunlap@infradead.org> :Author: Andrew Murray <amurray@mpc-data.co.uk> + Integer types ============= @@ -25,39 +26,45 @@ Integer types s64 %lld or %llx u64 %llu or %llx -If <type> is dependent on a config option for its size (e.g., ``sector_t``, -``blkcnt_t``) or is architecture-dependent for its size (e.g., ``tcflag_t``), -use a format specifier of its largest possible type and explicitly cast to it. + +If <type> is dependent on a config option for its size (e.g., sector_t, +blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a +format specifier of its largest possible type and explicitly cast to it. Example:: printk("test: sector number/total blocks: %llu/%llu\n", (unsigned long long)sector, (unsigned long long)blockcount); -Reminder: ``sizeof()`` result is of type ``size_t``. +Reminder: sizeof() returns type size_t. -The kernel's printf does not support ``%n``. For obvious reasons, floating -point formats (``%e, %f, %g, %a``) are also not recognized. Use of any +The kernel's printf does not support %n. Floating point formats (%e, %f, +%g, %a) are also not recognized, for obvious reasons. Use of any unsupported specifier or length qualifier results in a WARN and early -return from vsnprintf. - -Raw pointer value SHOULD be printed with %p. The kernel supports -the following extended format specifiers for pointer types: +return from vsnprintf(). -Pointer Types +Pointer types ============= -Pointers printed without a specifier extension (i.e unadorned %p) are -hashed to give a unique identifier without leaking kernel addresses to user -space. On 64 bit machines the first 32 bits are zeroed. If you _really_ -want the address see %px below. +A raw pointer value may be printed with %p which will hash the address +before printing. The kernel also supports extended specifiers for printing +pointers of different types. + +Plain Pointers +-------------- :: %p abcdef12 or 00000000abcdef12 +Pointers printed without a specifier extension (i.e unadorned %p) are +hashed to prevent leaking information about the kernel memory layout. This +has the added benefit of providing a unique identifier. On 64-bit machines +the first 32 bits are zeroed. If you *really* want the address see %px +below. + Symbols/Function Pointers -========================= +------------------------- :: @@ -69,6 +76,7 @@ Symbols/Function Pointers %ps versatile_init %pB prev_fn_of_versatile_init+0x88/0x88 + The ``F`` and ``f`` specifiers are for printing function pointers, for example, f->func, &gettimeofday. They have the same result as ``S`` and ``s`` specifiers. But they do an extra conversion on @@ -77,14 +85,14 @@ are actually function descriptors. The ``S`` and ``s`` specifiers can be used for printing symbols from direct addresses, for example, __builtin_return_address(0), -(void *)regs->ip. They result in the symbol name with (``S``) or -without (``s``) offsets. If KALLSYMS are disabled then the symbol +(void *)regs->ip. They result in the symbol name with (S) or +without (s) offsets. If KALLSYMS are disabled then the symbol address is printed instead. The ``B`` specifier results in the symbol name with offsets and should be used when printing stack backtraces. The specifier takes into consideration the effect of compiler optimisations which may occur -when tail-call``s are used and marked with the noreturn GCC attribute. +when tail-calls are used and marked with the noreturn GCC attribute. Examples:: @@ -97,33 +105,32 @@ Examples:: printk(" %s%pB\n", (reliable ? "" : "? "), (void *)*stack); Kernel Pointers -=============== +--------------- :: %pK 01234567 or 0123456789abcdef For printing kernel pointers which should be hidden from unprivileged -users. The behaviour of ``%pK`` depends on the ``kptr_restrict sysctl`` - see +users. The behaviour of %pK depends on the kptr_restrict sysctl - see Documentation/sysctl/kernel.txt for more details. Unmodified Addresses -==================== +-------------------- :: %px 01234567 or 0123456789abcdef -For printing pointers when you _really_ want to print the address. Please +For printing pointers when you *really* want to print the address. Please consider whether or not you are leaking sensitive information about the -Kernel layout in memory before printing pointers with %px. %px is -functionally equivalent to %lx. %px is preferred to %lx because it is more -uniquely grep'able. If, in the future, we need to modify the way the Kernel -handles printing pointers it will be nice to be able to find the call -sites. +kernel memory layout before printing pointers with %px. %px is functionally +equivalent to %lx (or %lu). %px is preferred because it is more uniquely +grep'able. If in the future we need to modify the way the kernel handles +printing pointers we will be better equipped to find the call sites. Struct Resources -================ +---------------- :: @@ -133,32 +140,37 @@ Struct Resources [mem 0x0000000060000000-0x000000006fffffff pref] For printing struct resources. The ``R`` and ``r`` specifiers result in a -printed resource with (``R``) or without (``r``) a decoded flags member. +printed resource with (R) or without (r) a decoded flags member. + Passed by reference. -Physical addresses types ``phys_addr_t`` -======================================== +Physical address types phys_addr_t +---------------------------------- :: %pa[p] 0x01234567 or 0x0123456789abcdef -For printing a ``phys_addr_t`` type (and its derivatives, such as -``resource_size_t``) which can vary based on build options, regardless of -the width of the CPU data path. Passed by reference. +For printing a phys_addr_t type (and its derivatives, such as +resource_size_t) which can vary based on build options, regardless of the +width of the CPU data path. + +Passed by reference. -DMA addresses types ``dma_addr_t`` -================================== +DMA address types dma_addr_t +---------------------------- :: %pad 0x01234567 or 0x0123456789abcdef -For printing a ``dma_addr_t`` type which can vary based on build options, -regardless of the width of the CPU data path. Passed by reference. +For printing a dma_addr_t type which can vary based on build options, +regardless of the width of the CPU data path. + +Passed by reference. Raw buffer as an escaped string -=============================== +------------------------------- :: @@ -168,8 +180,8 @@ For printing raw buffer as an escaped string. For the following buffer:: 1b 62 20 5c 43 07 22 90 0d 5d -few examples show how the conversion would be done (the result string -without surrounding quotes):: +A few examples show how the conversion would be done (excluding surrounding +quotes):: %*pE "\eb \C\a"\220\r]" %*pEhp "\x1bb \C\x07"\x90\x0d]" @@ -179,23 +191,23 @@ The conversion rules are applied according to an optional combination of flags (see :c:func:`string_escape_mem` kernel documentation for the details): - - ``a`` - ESCAPE_ANY - - ``c`` - ESCAPE_SPECIAL - - ``h`` - ESCAPE_HEX - - ``n`` - ESCAPE_NULL - - ``o`` - ESCAPE_OCTAL - - ``p`` - ESCAPE_NP - - ``s`` - ESCAPE_SPACE + - a - ESCAPE_ANY + - c - ESCAPE_SPECIAL + - h - ESCAPE_HEX + - n - ESCAPE_NULL + - o - ESCAPE_OCTAL + - p - ESCAPE_NP + - s - ESCAPE_SPACE By default ESCAPE_ANY_NP is used. ESCAPE_ANY_NP is the sane choice for many cases, in particularly for printing SSIDs. -If field width is omitted the 1 byte only will be escaped. +If field width is omitted then 1 byte only will be escaped. Raw buffer as a hex string -========================== +-------------------------- :: @@ -204,12 +216,12 @@ Raw buffer as a hex string %*phD 00-01-02- ... -3f %*phN 000102 ... 3f -For printing a small buffers (up to 64 bytes long) as a hex string with -certain separator. For the larger buffers consider to use +For printing small buffers (up to 64 bytes long) as a hex string with a +certain separator. For larger buffers consider using :c:func:`print_hex_dump`. MAC/FDDI addresses -================== +------------------ :: @@ -220,11 +232,11 @@ MAC/FDDI addresses %pmR 050403020100 For printing 6-byte MAC/FDDI addresses in hex notation. The ``M`` and ``m`` -specifiers result in a printed address with (``M``) or without (``m``) byte -separators. The default byte separator is the colon (``:``). +specifiers result in a printed address with (M) or without (m) byte +separators. The default byte separator is the colon (:). Where FDDI addresses are concerned the ``F`` specifier can be used after -the ``M`` specifier to use dash (``-``) separators instead of the default +the ``M`` specifier to use dash (-) separators instead of the default separator. For Bluetooth addresses the ``R`` specifier shall be used after the ``M`` @@ -234,7 +246,7 @@ of Bluetooth addresses which are in the little endian order. Passed by reference. IPv4 addresses -============== +-------------- :: @@ -243,8 +255,8 @@ IPv4 addresses %p[Ii]4[hnbl] For printing IPv4 dot-separated decimal addresses. The ``I4`` and ``i4`` -specifiers result in a printed address with (``i4``) or without (``I4``) -leading zeros. +specifiers result in a printed address with (i4) or without (I4) leading +zeros. The additional ``h``, ``n``, ``b``, and ``l`` specifiers are used to specify host, network, big or little endian order addresses respectively. Where @@ -253,7 +265,7 @@ no specifier is provided the default network/big endian order is used. Passed by reference. IPv6 addresses -============== +-------------- :: @@ -262,7 +274,7 @@ IPv6 addresses %pI6c 1:2:3:4:5:6:7:8 For printing IPv6 network-order 16-bit hex addresses. The ``I6`` and ``i6`` -specifiers result in a printed address with (``I6``) or without (``i6``) +specifiers result in a printed address with (I6) or without (i6) colon-separators. Leading zeros are always used. The additional ``c`` specifier can be used with the ``I`` specifier to @@ -272,7 +284,7 @@ http://tools.ietf.org/html/rfc5952 Passed by reference. IPv4/IPv6 addresses (generic, with port, flowinfo, scope) -========================================================= +--------------------------------------------------------- :: @@ -282,8 +294,8 @@ IPv4/IPv6 addresses (generic, with port, flowinfo, scope) %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345 %p[Ii]S[pfschnbl] -For printing an IP address without the need to distinguish whether it``s -of type AF_INET or AF_INET6, a pointer to a valid ``struct sockaddr``, +For printing an IP address without the need to distinguish whether it's of +type AF_INET or AF_INET6. A pointer to a valid struct sockaddr, specified through ``IS`` or ``iS``, can be passed to this format specifier. The additional ``p``, ``f``, and ``s`` specifiers are used to specify port @@ -309,7 +321,7 @@ Further examples:: %pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789 UUID/GUID addresses -=================== +------------------- :: @@ -318,33 +330,33 @@ UUID/GUID addresses %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F -For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', -'b' and 'B' specifiers are used to specify a little endian order in -lower ('l') or upper case ('L') hex characters - and big endian order -in lower ('b') or upper case ('B') hex characters. +For printing 16-byte UUID/GUIDs addresses. The additional ``l``, ``L``, +``b`` and ``B`` specifiers are used to specify a little endian order in +lower (l) or upper case (L) hex notation - and big endian order in lower (b) +or upper case (B) hex notation. Where no additional specifiers are used the default big endian -order with lower case hex characters will be printed. +order with lower case hex notation will be printed. Passed by reference. dentry names -============ +------------ :: %pd{,2,3,4} %pD{,2,3,4} -For printing dentry name; if we race with :c:func:`d_move`, the name might be -a mix of old and new ones, but it won't oops. ``%pd`` dentry is a safer -equivalent of ``%s`` ``dentry->d_name.name`` we used to use, ``%pd<n>`` prints -``n`` last components. ``%pD`` does the same thing for struct file. +For printing dentry name; if we race with :c:func:`d_move`, the name might +be a mix of old and new ones, but it won't oops. %pd dentry is a safer +equivalent of %s dentry->d_name.name we used to use, %pd<n> prints ``n`` +last components. %pD does the same thing for struct file. Passed by reference. block_device names -================== +------------------ :: @@ -353,7 +365,7 @@ block_device names For printing name of block_device pointers. struct va_format -================ +---------------- :: @@ -375,31 +387,27 @@ correctness of the format string and va_list arguments. Passed by reference. kobjects -======== +-------- :: - %pO + %pOF[fnpPcCF] - Base specifier for kobject based structs. Must be followed with - character for specific type of kobject as listed below: - Device tree nodes: +For printing kobject based structs (device nodes). Default behaviour is +equivalent to %pOFf. - %pOF[fnpPcCF] + - f - device node full_name + - n - device node name + - p - device node phandle + - P - device node path spec (name + @unit) + - F - device node flags + - c - major compatible string + - C - full compatible string - For printing device tree nodes. The optional arguments are: - f device node full_name - n device node name - p device node phandle - P device node path spec (name + @unit) - F device node flags - c major compatible string - C full compatible string - Without any arguments prints full_name (same as %pOFf) - The separator when using multiple arguments is ':' +The separator when using multiple arguments is ':' - Examples: +Examples:: %pOF /foo/bar@0 - Node full name %pOFf /foo/bar@0 - Same as above @@ -412,11 +420,10 @@ kobjects P - Populated B - Populated bus - Passed by reference. - +Passed by reference. struct clk -========== +---------- :: @@ -424,14 +431,14 @@ struct clk %pCn pll1 %pCr 1560000000 -For printing struct clk structures. ``%pC`` and ``%pCn`` print the name +For printing struct clk structures. %pC and %pCn print the name (Common Clock Framework) or address (legacy clock framework) of the -structure; ``%pCr`` prints the current clock rate. +structure; %pCr prints the current clock rate. Passed by reference. bitmap and its derivatives such as cpumask and nodemask -======================================================= +------------------------------------------------------- :: @@ -439,13 +446,13 @@ bitmap and its derivatives such as cpumask and nodemask %*pbl 0,3-6,8-10 For printing bitmap and its derivatives such as cpumask and nodemask, -``%*pb`` output the bitmap with field width as the number of bits and ``%*pbl`` +%*pb outputs the bitmap with field width as the number of bits and %*pbl output the bitmap as range list with field width as the number of bits. Passed by reference. Flags bitfields such as page flags, gfp_flags -============================================= +--------------------------------------------- :: @@ -459,14 +466,14 @@ character. Currently supported are [p]age flags, [v]ma_flags (both expect ``unsigned long *``) and [g]fp_flags (expects ``gfp_t *``). The flag names and print order depends on the particular type. -Note that this format should not be used directly in :c:func:`TP_printk()` part -of a tracepoint. Instead, use the ``show_*_flags()`` functions from -<trace/events/mmflags.h>. +Note that this format should not be used directly in the +:c:func:`TP_printk()` part of a tracepoint. Instead, use the show_*_flags() +functions from <trace/events/mmflags.h>. Passed by reference. Network device features -======================= +----------------------- :: @@ -476,8 +483,10 @@ For printing netdev_features_t. Passed by reference. -If you add other ``%p`` extensions, please extend lib/test_printf.c with -one or more test cases, if at all feasible. +Thanks +====== +If you add other %p extensions, please extend <lib/test_printf.c> with +one or more test cases, if at all feasible. Thank you for your cooperation and attention. diff --git a/Documentation/core-api/refcount-vs-atomic.rst b/Documentation/core-api/refcount-vs-atomic.rst new file mode 100644 index 000000000000..83351c258cdb --- /dev/null +++ b/Documentation/core-api/refcount-vs-atomic.rst @@ -0,0 +1,150 @@ +=================================== +refcount_t API compared to atomic_t +=================================== + +.. contents:: :local: + +Introduction +============ + +The goal of refcount_t API is to provide a minimal API for implementing +an object's reference counters. While a generic architecture-independent +implementation from lib/refcount.c uses atomic operations underneath, +there are a number of differences between some of the ``refcount_*()`` and +``atomic_*()`` functions with regards to the memory ordering guarantees. +This document outlines the differences and provides respective examples +in order to help maintainers validate their code against the change in +these memory ordering guarantees. + +The terms used through this document try to follow the formal LKMM defined in +github.com/aparri/memory-model/blob/master/Documentation/explanation.txt + +memory-barriers.txt and atomic_t.txt provide more background to the +memory ordering in general and for atomic operations specifically. + +Relevant types of memory ordering +================================= + +.. note:: The following section only covers some of the memory + ordering types that are relevant for the atomics and reference + counters and used through this document. For a much broader picture + please consult memory-barriers.txt document. + +In the absence of any memory ordering guarantees (i.e. fully unordered) +atomics & refcounters only provide atomicity and +program order (po) relation (on the same CPU). It guarantees that +each ``atomic_*()`` and ``refcount_*()`` operation is atomic and instructions +are executed in program order on a single CPU. +This is implemented using :c:func:`READ_ONCE`/:c:func:`WRITE_ONCE` and +compare-and-swap primitives. + +A strong (full) memory ordering guarantees that all prior loads and +stores (all po-earlier instructions) on the same CPU are completed +before any po-later instruction is executed on the same CPU. +It also guarantees that all po-earlier stores on the same CPU +and all propagated stores from other CPUs must propagate to all +other CPUs before any po-later instruction is executed on the original +CPU (A-cumulative property). This is implemented using :c:func:`smp_mb`. + +A RELEASE memory ordering guarantees that all prior loads and +stores (all po-earlier instructions) on the same CPU are completed +before the operation. It also guarantees that all po-earlier +stores on the same CPU and all propagated stores from other CPUs +must propagate to all other CPUs before the release operation +(A-cumulative property). This is implemented using +:c:func:`smp_store_release`. + +A control dependency (on success) for refcounters guarantees that +if a reference for an object was successfully obtained (reference +counter increment or addition happened, function returned true), +then further stores are ordered against this operation. +Control dependency on stores are not implemented using any explicit +barriers, but rely on CPU not to speculate on stores. This is only +a single CPU relation and provides no guarantees for other CPUs. + + +Comparison of functions +======================= + +case 1) - non-"Read/Modify/Write" (RMW) ops +------------------------------------------- + +Function changes: + + * :c:func:`atomic_set` --> :c:func:`refcount_set` + * :c:func:`atomic_read` --> :c:func:`refcount_read` + +Memory ordering guarantee changes: + + * none (both fully unordered) + + +case 2) - increment-based ops that return no value +-------------------------------------------------- + +Function changes: + + * :c:func:`atomic_inc` --> :c:func:`refcount_inc` + * :c:func:`atomic_add` --> :c:func:`refcount_add` + +Memory ordering guarantee changes: + + * none (both fully unordered) + +case 3) - decrement-based RMW ops that return no value +------------------------------------------------------ + +Function changes: + + * :c:func:`atomic_dec` --> :c:func:`refcount_dec` + +Memory ordering guarantee changes: + + * fully unordered --> RELEASE ordering + + +case 4) - increment-based RMW ops that return a value +----------------------------------------------------- + +Function changes: + + * :c:func:`atomic_inc_not_zero` --> :c:func:`refcount_inc_not_zero` + * no atomic counterpart --> :c:func:`refcount_add_not_zero` + +Memory ordering guarantees changes: + + * fully ordered --> control dependency on success for stores + +.. note:: We really assume here that necessary ordering is provided as a + result of obtaining pointer to the object! + + +case 5) - decrement-based RMW ops that return a value +----------------------------------------------------- + +Function changes: + + * :c:func:`atomic_dec_and_test` --> :c:func:`refcount_dec_and_test` + * :c:func:`atomic_sub_and_test` --> :c:func:`refcount_sub_and_test` + * no atomic counterpart --> :c:func:`refcount_dec_if_one` + * ``atomic_add_unless(&var, -1, 1)`` --> ``refcount_dec_not_one(&var)`` + +Memory ordering guarantees changes: + + * fully ordered --> RELEASE ordering + control dependency + +.. note:: :c:func:`atomic_add_unless` only provides full order on success. + + +case 6) - lock-based RMW +------------------------ + +Function changes: + + * :c:func:`atomic_dec_and_lock` --> :c:func:`refcount_dec_and_lock` + * :c:func:`atomic_dec_and_mutex_lock` --> :c:func:`refcount_dec_and_mutex_lock` + +Memory ordering guarantees changes: + + * fully ordered --> RELEASE ordering + control dependency + hold + :c:func:`spin_lock` on success diff --git a/Documentation/doc-guide/kernel-doc.rst b/Documentation/doc-guide/kernel-doc.rst index 0268335414ce..722d4525f7cf 100644 --- a/Documentation/doc-guide/kernel-doc.rst +++ b/Documentation/doc-guide/kernel-doc.rst @@ -112,16 +112,17 @@ Example kernel-doc function comment:: /** * foobar() - Brief description of foobar. - * @arg: Description of argument of foobar. + * @argument1: Description of parameter argument1 of foobar. + * @argument2: Description of parameter argument2 of foobar. * * Longer description of foobar. * * Return: Description of return value of foobar. */ - int foobar(int arg) + int foobar(int argument1, char *argument2) The format is similar for documentation for structures, enums, paragraphs, -etc. See the sections below for details. +etc. See the sections below for specific details of each type. The kernel-doc structure is extracted from the comments, and proper `Sphinx C Domain`_ function and type descriptions with anchors are generated for them. The @@ -130,6 +131,226 @@ cross-references. See below for details. .. _Sphinx C Domain: http://www.sphinx-doc.org/en/stable/domains.html + +Parameters and member arguments +------------------------------- + +The kernel-doc function comments describe each parameter to the function and +function typedefs or each member of struct/union, in order, with the +``@argument:`` descriptions. For each non-private member argument, one +``@argument`` definition is needed. + +The ``@argument:`` descriptions begin on the very next line following +the opening brief function description line, with no intervening blank +comment lines. + +The ``@argument:`` descriptions may span multiple lines. + +.. note:: + + If the ``@argument`` description has multiple lines, the continuation + of the description should be starting exactly at the same column as + the previous line, e. g.:: + + * @argument: some long description + * that continues on next lines + + or:: + + * @argument: + * some long description + * that continues on next lines + +If a function or typedef parameter argument is ``...`` (e. g. a variable +number of arguments), its description should be listed in kernel-doc +notation as:: + + * @...: description + +Private members +~~~~~~~~~~~~~~~ + +Inside a struct or union description, you can use the ``private:`` and +``public:`` comment tags. Structure fields that are inside a ``private:`` +area are not listed in the generated output documentation. + +The ``private:`` and ``public:`` tags must begin immediately following a +``/*`` comment marker. They may optionally include comments between the +``:`` and the ending ``*/`` marker. + +Example:: + + /** + * struct my_struct - short description + * @a: first member + * @b: second member + * @d: fourth member + * + * Longer description + */ + struct my_struct { + int a; + int b; + /* private: internal use only */ + int c; + /* public: the next one is public */ + int d; + }; + +Function documentation +---------------------- + +The general format of a function and function-like macro kernel-doc comment is:: + + /** + * function_name() - Brief description of function. + * @arg1: Describe the first argument. + * @arg2: Describe the second argument. + * One can provide multiple line descriptions + * for arguments. + * + * A longer description, with more discussion of the function function_name() + * that might be useful to those using or modifying it. Begins with an + * empty comment line, and may include additional embedded empty + * comment lines. + * + * The longer description may have multiple paragraphs. + * + * Return: Describe the return value of foobar. + * + * The return value description can also have multiple paragraphs, and should + * be placed at the end of the comment block. + */ + +The brief description following the function name may span multiple lines, and +ends with an argument description, a blank comment line, or the end of the +comment block. + +Return values +~~~~~~~~~~~~~ + +The return value, if any, should be described in a dedicated section +named ``Return``. + +.. note:: + + #) The multi-line descriptive text you provide does *not* recognize + line breaks, so if you try to format some text nicely, as in:: + + * Return: + * 0 - OK + * -EINVAL - invalid argument + * -ENOMEM - out of memory + + this will all run together and produce:: + + Return: 0 - OK -EINVAL - invalid argument -ENOMEM - out of memory + + So, in order to produce the desired line breaks, you need to use a + ReST list, e. g.:: + + * Return: + * * 0 - OK to runtime suspend the device + * * -EBUSY - Device should not be runtime suspended + + #) If the descriptive text you provide has lines that begin with + some phrase followed by a colon, each of those phrases will be taken + as a new section heading, with probably won't produce the desired + effect. + +Structure, union, and enumeration documentation +----------------------------------------------- + +The general format of a struct, union, and enum kernel-doc comment is:: + + /** + * struct struct_name - Brief description. + * @argument: Description of member member_name. + * + * Description of the structure. + */ + +On the above, ``struct`` is used to mean structs. You can also use ``union`` +and ``enum`` to describe unions and enums. ``argument`` is used +to mean struct and union member names as well as enumerations in an enum. + +The brief description following the structure name may span multiple lines, and +ends with a member description, a blank comment line, or the end of the +comment block. + +The kernel-doc data structure comments describe each member of the structure, +in order, with the member descriptions. + +Nested structs/unions +~~~~~~~~~~~~~~~~~~~~~ + +It is possible to document nested structs unions, like:: + + /** + * struct nested_foobar - a struct with nested unions and structs + * @arg1: - first argument of anonymous union/anonymous struct + * @arg2: - second argument of anonymous union/anonymous struct + * @arg3: - third argument of anonymous union/anonymous struct + * @arg4: - fourth argument of anonymous union/anonymous struct + * @bar.st1.arg1 - first argument of struct st1 on union bar + * @bar.st1.arg2 - second argument of struct st1 on union bar + * @bar.st2.arg1 - first argument of struct st2 on union bar + * @bar.st2.arg2 - second argument of struct st2 on union bar + struct nested_foobar { + /* Anonymous union/struct*/ + union { + struct { + int arg1; + int arg2; + } + struct { + void *arg3; + int arg4; + } + } + union { + struct { + int arg1; + int arg2; + } st1; + struct { + void *arg1; + int arg2; + } st2; + } bar; + }; + +.. note:: + + #) When documenting nested structs or unions, if the struct/union ``foo`` + is named, the argument ``bar`` inside it should be documented as + ``@foo.bar:`` + #) When the nested struct/union is anonymous, the argument ``bar`` on it + should be documented as ``@bar:`` + +Typedef documentation +--------------------- + +The general format of a typedef kernel-doc comment is:: + + /** + * typedef type_name - Brief description. + * + * Description of the type. + */ + +Typedefs with function prototypes can also be documented:: + + /** + * typedef type_name - Brief description. + * @arg1: description of arg1 + * @arg2: description of arg2 + * + * Description of the type. + */ + typedef void (*type_name)(struct v4l2_ctrl *arg1, void *arg2); + + Highlights and cross-references ------------------------------- @@ -201,70 +422,7 @@ cross-references. For further details, please refer to the `Sphinx C Domain`_ documentation. -Function documentation ----------------------- - -The general format of a function and function-like macro kernel-doc comment is:: - - /** - * function_name() - Brief description of function. - * @arg1: Describe the first argument. - * @arg2: Describe the second argument. - * One can provide multiple line descriptions - * for arguments. - * - * A longer description, with more discussion of the function function_name() - * that might be useful to those using or modifying it. Begins with an - * empty comment line, and may include additional embedded empty - * comment lines. - * - * The longer description may have multiple paragraphs. - * - * Return: Describe the return value of foobar. - * - * The return value description can also have multiple paragraphs, and should - * be placed at the end of the comment block. - */ - -The brief description following the function name may span multiple lines, and -ends with an ``@argument:`` description, a blank comment line, or the end of the -comment block. - -The kernel-doc function comments describe each parameter to the function, in -order, with the ``@argument:`` descriptions. The ``@argument:`` descriptions -must begin on the very next line following the opening brief function -description line, with no intervening blank comment lines. The ``@argument:`` -descriptions may span multiple lines. The continuation lines may contain -indentation. If a function parameter is ``...`` (varargs), it should be listed -in kernel-doc notation as: ``@...:``. - -The return value, if any, should be described in a dedicated section at the end -of the comment starting with "Return:". - -Structure, union, and enumeration documentation ------------------------------------------------ - -The general format of a struct, union, and enum kernel-doc comment is:: - - /** - * struct struct_name - Brief description. - * @member_name: Description of member member_name. - * - * Description of the structure. - */ - -Below, "struct" is used to mean structs, unions and enums, and "member" is used -to mean struct and union members as well as enumerations in an enum. - -The brief description following the structure name may span multiple lines, and -ends with a ``@member:`` description, a blank comment line, or the end of the -comment block. -The kernel-doc data structure comments describe each member of the structure, in -order, with the ``@member:`` descriptions. The ``@member:`` descriptions must -begin on the very next line following the opening brief function description -line, with no intervening blank comment lines. The ``@member:`` descriptions may -span multiple lines. The continuation lines may contain indentation. In-line member documentation comments ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -294,42 +452,6 @@ on a line of their own, like all other kernel-doc comments:: int foobar; } -Private members -~~~~~~~~~~~~~~~ - -Inside a struct description, you can use the "private:" and "public:" comment -tags. Structure fields that are inside a "private:" area are not listed in the -generated output documentation. The "private:" and "public:" tags must begin -immediately following a ``/*`` comment marker. They may optionally include -comments between the ``:`` and the ending ``*/`` marker. - -Example:: - - /** - * struct my_struct - short description - * @a: first member - * @b: second member - * - * Longer description - */ - struct my_struct { - int a; - int b; - /* private: internal use only */ - int c; - }; - - -Typedef documentation ---------------------- - -The general format of a typedef kernel-doc comment is:: - - /** - * typedef type_name - Brief description. - * - * Description of the type. - */ Overview documentation comments ------------------------------- @@ -376,3 +498,37 @@ file. Data structures visible in kernel include files should also be documented using kernel-doc formatted comments. + +How to use kernel-doc to generate man pages +------------------------------------------- + +If you just want to use kernel-doc to generate man pages you can do this +from the Kernel git tree:: + + $ scripts/kernel-doc -man $(git grep -l '/\*\*' |grep -v Documentation/) | ./split-man.pl /tmp/man + +Using the small ``split-man.pl`` script below:: + + + #!/usr/bin/perl + + if ($#ARGV < 0) { + die "where do I put the results?\n"; + } + + mkdir $ARGV[0],0777; + $state = 0; + while (<STDIN>) { + if (/^\.TH \"[^\"]*\" 9 \"([^\"]*)\"/) { + if ($state == 1) { close OUT } + $state = 1; + $fn = "$ARGV[0]/$1.9"; + print STDERR "Creating $fn\n"; + open OUT, ">$fn" or die "can't open $fn: $!\n"; + print OUT $_; + } elsif ($state != 0) { + print OUT $_; + } + } + + close OUT; diff --git a/Documentation/driver-api/basics.rst b/Documentation/driver-api/basics.rst index 73fa7d42bbba..826e85d50a16 100644 --- a/Documentation/driver-api/basics.rst +++ b/Documentation/driver-api/basics.rst @@ -13,12 +13,6 @@ Driver device table .. kernel-doc:: include/linux/mod_devicetable.h :internal: -Atomic and pointer manipulation -------------------------------- - -.. kernel-doc:: arch/x86/include/asm/atomic.h - :internal: - Delaying, scheduling, and timer routines ---------------------------------------- @@ -85,6 +79,21 @@ Internal Functions .. kernel-doc:: kernel/kthread.c :export: +Reference counting +------------------ + +.. kernel-doc:: include/linux/refcount.h + :internal: + +.. kernel-doc:: lib/refcount.c + :export: + +Atomics +------- + +.. kernel-doc:: arch/x86/include/asm/atomic.h + :internal: + Kernel objects manipulation --------------------------- diff --git a/Documentation/driver-api/usb/usb3-debug-port.rst b/Documentation/driver-api/usb/usb3-debug-port.rst index feb1a36a65b7..b9fd131f4723 100644 --- a/Documentation/driver-api/usb/usb3-debug-port.rst +++ b/Documentation/driver-api/usb/usb3-debug-port.rst @@ -98,3 +98,55 @@ you to check the sanity of the setup. cat /dev/ttyUSB0 done ===== end of bash scripts =============== + +Serial TTY +========== + +The DbC support has been added to the xHCI driver. You can get a +debug device provided by the DbC at runtime. + +In order to use this, you need to make sure your kernel has been +configured to support USB_XHCI_DBGCAP. A sysfs attribute under +the xHCI device node is used to enable or disable DbC. By default, +DbC is disabled:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# cat dbc + disabled + +Enable DbC with the following command:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# echo enable > dbc + +You can check the DbC state at anytime:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# cat dbc + enabled + +Connect the debug target to the debug host with a USB 3.0 super- +speed A-to-A debugging cable. You can see /dev/ttyDBC0 created +on the debug target. You will see below kernel message lines:: + + root@target: tail -f /var/log/kern.log + [ 182.730103] xhci_hcd 0000:00:14.0: DbC connected + [ 191.169420] xhci_hcd 0000:00:14.0: DbC configured + [ 191.169597] xhci_hcd 0000:00:14.0: DbC now attached to /dev/ttyDBC0 + +Accordingly, the DbC state has been brought up to:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# cat dbc + configured + +On the debug host, you will see the debug device has been enumerated. +You will see below kernel message lines:: + + root@host: tail -f /var/log/kern.log + [ 79.454780] usb 2-2.1: new SuperSpeed USB device number 3 using xhci_hcd + [ 79.475003] usb 2-2.1: LPM exit latency is zeroed, disabling LPM. + [ 79.475389] usb 2-2.1: New USB device found, idVendor=1d6b, idProduct=0010 + [ 79.475390] usb 2-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 + [ 79.475391] usb 2-2.1: Product: Linux USB Debug Target + [ 79.475392] usb 2-2.1: Manufacturer: Linux Foundation + [ 79.475393] usb 2-2.1: SerialNumber: 0001 + +The debug device works now. You can use any communication or debugging +program to talk between the host and the target. diff --git a/Documentation/driver-api/usb/writing_usb_driver.rst b/Documentation/driver-api/usb/writing_usb_driver.rst index 69f077dcdb78..4fe1c06b6a13 100644 --- a/Documentation/driver-api/usb/writing_usb_driver.rst +++ b/Documentation/driver-api/usb/writing_usb_driver.rst @@ -321,6 +321,6 @@ linux-usb-devel Mailing List Archives: http://marc.theaimsgroup.com/?l=linux-usb-devel Programming Guide for Linux USB Device Drivers: -http://usb.cs.tum.edu/usbdoc +http://lmu.web.psi.ch/docu/manuals/software_manuals/linux_sl/usb_linux_programming_guide.pdf USB Home Page: http://www.usb.org diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt index f4a32463ca48..de1dc35fe500 100644 --- a/Documentation/fault-injection/fault-injection.txt +++ b/Documentation/fault-injection/fault-injection.txt @@ -1,7 +1,7 @@ Fault injection capabilities infrastructure =========================================== -See also drivers/md/faulty.c and "every_nth" module option for scsi_debug. +See also drivers/md/md-faulty.c and "every_nth" module option for scsi_debug. Available fault injection capabilities diff --git a/Documentation/filesystems/ext2.txt b/Documentation/filesystems/ext2.txt index 55755395d3dc..81c0becab225 100644 --- a/Documentation/filesystems/ext2.txt +++ b/Documentation/filesystems/ext2.txt @@ -49,12 +49,10 @@ sb=n Use alternate superblock at this location. user_xattr Enable "user." POSIX Extended Attributes (requires CONFIG_EXT2_FS_XATTR). - See also http://acl.bestbits.at nouser_xattr Don't support "user." extended attributes. acl Enable POSIX Access Control Lists support (requires CONFIG_EXT2_FS_POSIX_ACL). - See also http://acl.bestbits.at noacl Don't support POSIX ACLs. nobh Do not attach buffer_heads to file pagecache. diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt index 75236c0c2ac2..8cd63e16f171 100644 --- a/Documentation/filesystems/ext4.txt +++ b/Documentation/filesystems/ext4.txt @@ -202,15 +202,14 @@ inode_readahead_blks=n This tuning parameter controls the maximum the buffer cache. The default value is 32 blocks. nouser_xattr Disables Extended User Attributes. See the - attr(5) manual page and http://acl.bestbits.at/ - for more information about extended attributes. + attr(5) manual page for more information about + extended attributes. noacl This option disables POSIX Access Control List support. If ACL support is enabled in the kernel configuration (CONFIG_EXT4_FS_POSIX_ACL), ACL is enabled by default on mount. See the acl(5) manual - page and http://acl.bestbits.at/ for more information - about acl. + page for more information about acl. bsddf (*) Make 'df' act like BSD. minixdf Make 'df' act like Minix. diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index cf51360e3a9f..91031298beb1 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -344,4 +344,4 @@ the following: characters in the final slot are set to Unicode 0xFFFF. Finally, note that the extended name is stored in Unicode. Each Unicode -character takes two bytes. +character takes either two or four bytes, UTF-16LE encoded. diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface index 5ff19447ac44..d04e6e4964ee 100644 --- a/Documentation/i2c/dev-interface +++ b/Documentation/i2c/dev-interface @@ -17,13 +17,16 @@ i2c-10, ...). All 256 minor device numbers are reserved for i2c. C example ========= -So let's say you want to access an i2c adapter from a C program. The -first thing to do is "#include <linux/i2c-dev.h>". Please note that -there are two files named "i2c-dev.h" out there, one is distributed -with the Linux kernel and is meant to be included from kernel -driver code, the other one is distributed with i2c-tools and is -meant to be included from user-space programs. You obviously want -the second one here. +So let's say you want to access an i2c adapter from a C program. +First, you need to include these two headers: + + #include <linux/i2c-dev.h> + #include <i2c/smbus.h> + +(Please note that there are two files named "i2c-dev.h" out there. One is +distributed with the Linux kernel and the other one is included in the +source tree of i2c-tools. They used to be different in content but since 2012 +they're identical. You should use "linux/i2c-dev.h"). Now, you have to decide which adapter you want to access. You should inspect /sys/class/i2c-dev/ or run "i2cdetect -l" to decide this. diff --git a/Documentation/index.rst b/Documentation/index.rst index cb7f1ba5b3b1..ef5080cbf009 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -13,6 +13,18 @@ documents into a coherent whole. Please note that improvements to the documentation are welcome; join the linux-doc list at vger.kernel.org if you want to help out. +Licensing documentation +----------------------- + +The following describes the license of the Linux kernel source code +(GPLv2), how to properly mark the license of individual files in the source +tree, as well as links to the full license text. + +.. toctree:: + :maxdepth: 2 + + process/license-rules.rst + User-oriented documentation --------------------------- @@ -52,6 +64,7 @@ merged much easier. dev-tools/index doc-guide/index kernel-hacking/index + maintainer/index Kernel API documentation ------------------------ diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt index c4a293a03c33..f5b9493f04ad 100644 --- a/Documentation/kbuild/kconfig-language.txt +++ b/Documentation/kbuild/kconfig-language.txt @@ -77,6 +77,27 @@ applicable everywhere (see syntax). Optionally, dependencies only for this default value can be added with "if". + The default value deliberately defaults to 'n' in order to avoid bloating the + build. With few exceptions, new config options should not change this. The + intent is for "make oldconfig" to add as little as possible to the config from + release to release. + + Note: + Things that merit "default y/m" include: + + a) A new Kconfig option for something that used to always be built + should be "default y". + + b) A new gatekeeping Kconfig option that hides/shows other Kconfig + options (but does not generate any code of its own), should be + "default y" so people will see those other options. + + c) Sub-driver behavior or similar options for a driver that is + "default n". This allows you to provide sane defaults. + + d) Hardware or infrastructure that everybody expects, such as CONFIG_NET + or CONFIG_BLOCK. These are rare exceptions. + - type definition + default value: "def_bool"/"def_tristate" <expr> ["if" <expr>] This is a shorthand notation for a type definition plus a value. diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt deleted file mode 100644 index c23e2c5ab80d..000000000000 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ /dev/null @@ -1,322 +0,0 @@ -NOTE: this document is outdated and will eventually be removed. See -Documentation/doc-guide/ for current information. - -kernel-doc nano-HOWTO -===================== - -How to format kernel-doc comments ---------------------------------- - -In order to provide embedded, 'C' friendly, easy to maintain, -but consistent and extractable documentation of the functions and -data structures in the Linux kernel, the Linux kernel has adopted -a consistent style for documenting functions and their parameters, -and structures and their members. - -The format for this documentation is called the kernel-doc format. -It is documented in this Documentation/kernel-doc-nano-HOWTO.txt file. - -This style embeds the documentation within the source files, using -a few simple conventions. The scripts/kernel-doc perl script, the -Documentation/sphinx/kerneldoc.py Sphinx extension and other tools understand -these conventions, and are used to extract this embedded documentation -into various documents. - -In order to provide good documentation of kernel functions and data -structures, please use the following conventions to format your -kernel-doc comments in Linux kernel source. - -We definitely need kernel-doc formatted documentation for functions -that are exported to loadable modules using EXPORT_SYMBOL. - -We also look to provide kernel-doc formatted documentation for -functions externally visible to other kernel files (not marked -"static"). - -We also recommend providing kernel-doc formatted documentation -for private (file "static") routines, for consistency of kernel -source code layout. But this is lower priority and at the -discretion of the MAINTAINER of that kernel source file. - -Data structures visible in kernel include files should also be -documented using kernel-doc formatted comments. - -The opening comment mark "/**" is reserved for kernel-doc comments. -Only comments so marked will be considered by the kernel-doc scripts, -and any comment so marked must be in kernel-doc format. Do not use -"/**" to be begin a comment block unless the comment block contains -kernel-doc formatted comments. The closing comment marker for -kernel-doc comments can be either "*/" or "**/", but "*/" is -preferred in the Linux kernel tree. - -Kernel-doc comments should be placed just before the function -or data structure being described. - -Example kernel-doc function comment: - -/** - * foobar() - short function description of foobar - * @arg1: Describe the first argument to foobar. - * @arg2: Describe the second argument to foobar. - * One can provide multiple line descriptions - * for arguments. - * - * A longer description, with more discussion of the function foobar() - * that might be useful to those using or modifying it. Begins with - * empty comment line, and may include additional embedded empty - * comment lines. - * - * The longer description can have multiple paragraphs. - * - * Return: Describe the return value of foobar. - */ - -The short description following the subject can span multiple lines -and ends with an @argument description, an empty line or the end of -the comment block. - -The @argument descriptions must begin on the very next line following -this opening short function description line, with no intervening -empty comment lines. - -If a function parameter is "..." (varargs), it should be listed in -kernel-doc notation as: - * @...: description - -The return value, if any, should be described in a dedicated section -named "Return". - -Example kernel-doc data structure comment. - -/** - * struct blah - the basic blah structure - * @mem1: describe the first member of struct blah - * @mem2: describe the second member of struct blah, - * perhaps with more lines and words. - * - * Longer description of this structure. - */ - -The kernel-doc function comments describe each parameter to the -function, in order, with the @name lines. - -The kernel-doc data structure comments describe each structure member -in the data structure, with the @name lines. - -The longer description formatting is "reflowed", losing your line -breaks. So presenting carefully formatted lists within these -descriptions won't work so well; derived documentation will lose -the formatting. - -See the section below "How to add extractable documentation to your -source files" for more details and notes on how to format kernel-doc -comments. - -Components of the kernel-doc system ------------------------------------ - -Many places in the source tree have extractable documentation in the -form of block comments above functions. The components of this system -are: - -- scripts/kernel-doc - - This is a perl script that hunts for the block comments and can mark - them up directly into DocBook, ReST, man, text, and HTML. (No, not - texinfo.) - -- scripts/docproc.c - - This is a program for converting SGML template files into SGML - files. When a file is referenced it is searched for symbols - exported (EXPORT_SYMBOL), to be able to distinguish between internal - and external functions. - It invokes kernel-doc, giving it the list of functions that - are to be documented. - Additionally it is used to scan the SGML template files to locate - all the files referenced herein. This is used to generate dependency - information as used by make. - -- Makefile - - The targets 'xmldocs', 'latexdocs', 'pdfdocs', 'epubdocs'and 'htmldocs' - are used to build XML DocBook files, LaTeX files, PDF files, - ePub files and html files in Documentation/. - -How to extract the documentation --------------------------------- - -If you just want to read the ready-made books on the various -subsystems, just type 'make epubdocs', or 'make pdfdocs', or 'make htmldocs', -depending on your preference. If you would rather read a different format, -you can type 'make xmldocs' and then use DocBook tools to convert -Documentation/output/*.xml to a format of your choice (for example, -'db2html ...' if 'make htmldocs' was not defined). - -If you want to see man pages instead, you can do this: - -$ cd linux -$ scripts/kernel-doc -man $(find -name '*.c') | split-man.pl /tmp/man -$ scripts/kernel-doc -man $(find -name '*.h') | split-man.pl /tmp/man - -Here is split-man.pl: - ---> -#!/usr/bin/perl - -if ($#ARGV < 0) { - die "where do I put the results?\n"; -} - -mkdir $ARGV[0],0777; -$state = 0; -while (<STDIN>) { - if (/^\.TH \"[^\"]*\" 9 \"([^\"]*)\"/) { - if ($state == 1) { close OUT } - $state = 1; - $fn = "$ARGV[0]/$1.9"; - print STDERR "Creating $fn\n"; - open OUT, ">$fn" or die "can't open $fn: $!\n"; - print OUT $_; - } elsif ($state != 0) { - print OUT $_; - } -} - -close OUT; -<-- - -If you just want to view the documentation for one function in one -file, you can do this: - -$ scripts/kernel-doc -man -function fn file | nroff -man | less - -or this: - -$ scripts/kernel-doc -text -function fn file - - -How to add extractable documentation to your source files ---------------------------------------------------------- - -The format of the block comment is like this: - -/** - * function_name(:)? (- short description)? -(* @parameterx(space)*: (description of parameter x)?)* -(* a blank line)? - * (Description:)? (Description of function)? - * (section header: (section description)? )* -(*)?*/ - -All "description" text can span multiple lines, although the -function_name & its short description are traditionally on a single line. -Description text may also contain blank lines (i.e., lines that contain -only a "*"). - -"section header:" names must be unique per function (or struct, -union, typedef, enum). - -Use the section header "Return" for sections describing the return value -of a function. - -Avoid putting a spurious blank line after the function name, or else the -description will be repeated! - -All descriptive text is further processed, scanning for the following special -patterns, which are highlighted appropriately. - -'funcname()' - function -'$ENVVAR' - environment variable -'&struct_name' - name of a structure (up to two words including 'struct') -'@parameter' - name of a parameter -'%CONST' - name of a constant. - -NOTE 1: The multi-line descriptive text you provide does *not* recognize -line breaks, so if you try to format some text nicely, as in: - - Return: - 0 - cool - 1 - invalid arg - 2 - out of memory - -this will all run together and produce: - - Return: 0 - cool 1 - invalid arg 2 - out of memory - -NOTE 2: If the descriptive text you provide has lines that begin with -some phrase followed by a colon, each of those phrases will be taken as -a new section heading, which means you should similarly try to avoid text -like: - - Return: - 0: cool - 1: invalid arg - 2: out of memory - -every line of which would start a new section. Again, probably not -what you were after. - -Take a look around the source tree for examples. - - -kernel-doc for structs, unions, enums, and typedefs ---------------------------------------------------- - -Beside functions you can also write documentation for structs, unions, -enums and typedefs. Instead of the function name you must write the name -of the declaration; the struct/union/enum/typedef must always precede -the name. Nesting of declarations is not supported. -Use the argument mechanism to document members or constants. - -Inside a struct description, you can use the "private:" and "public:" -comment tags. Structure fields that are inside a "private:" area -are not listed in the generated output documentation. The "private:" -and "public:" tags must begin immediately following a "/*" comment -marker. They may optionally include comments between the ":" and the -ending "*/" marker. - -Example: - -/** - * struct my_struct - short description - * @a: first member - * @b: second member - * - * Longer description - */ -struct my_struct { - int a; - int b; -/* private: internal use only */ - int c; -}; - - -Including documentation blocks in source files ----------------------------------------------- - -To facilitate having source code and comments close together, you can -include kernel-doc documentation blocks that are free-form comments -instead of being kernel-doc for functions, structures, unions, -enums, or typedefs. This could be used for something like a -theory of operation for a driver or library code, for example. - -This is done by using a DOC: section keyword with a section title. E.g.: - -/** - * DOC: Theory of Operation - * - * The whizbang foobar is a dilly of a gizmo. It can do whatever you - * want it to do, at any time. It reads your mind. Here's how it works. - * - * foo bar splat - * - * The only drawback to this gizmo is that is can sometimes damage - * hardware, software, or its subject(s). - */ - -DOC: sections are used in ReST files. - -Tim. -*/ <twaugh@redhat.com> diff --git a/Documentation/kernel-hacking/hacking.rst b/Documentation/kernel-hacking/hacking.rst index daf3883b2694..9999c8468293 100644 --- a/Documentation/kernel-hacking/hacking.rst +++ b/Documentation/kernel-hacking/hacking.rst @@ -523,7 +523,7 @@ this expression is true, or ``-ERESTARTSYS`` if a signal is received. The Waking Up Queued Tasks ---------------------- -Call :c:func:`wake_up()` (``include/linux/wait.h``);, which will wake +Call :c:func:`wake_up()` (``include/linux/wait.h``), which will wake up every process in the queue. The exception is if one has ``TASK_EXCLUSIVE`` set, in which case the remainder of the queue will not be woken. There are other variants of this basic function available @@ -690,8 +690,8 @@ not provide the necessary runtime environment and the include files are not tested for it. It is still possible, but not recommended. If you really want to do this, forget about exceptions at least. -NUMif ------ +#if +--- It is generally considered cleaner to use macros in header files (or at the top of .c files) to abstract away functions rather than using \`#if' diff --git a/Documentation/maintainer/conf.py b/Documentation/maintainer/conf.py new file mode 100644 index 000000000000..81e9eb7a7884 --- /dev/null +++ b/Documentation/maintainer/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = 'Linux Kernel Development Documentation' + +tags.add("subproject") + +latex_documents = [ + ('index', 'maintainer.tex', 'Linux Kernel Development Documentation', + 'The kernel development community', 'manual'), +] diff --git a/Documentation/maintainer/configure-git.rst b/Documentation/maintainer/configure-git.rst new file mode 100644 index 000000000000..78bbbb0d2c84 --- /dev/null +++ b/Documentation/maintainer/configure-git.rst @@ -0,0 +1,34 @@ +.. _configuregit: + +Configure Git +============= + +This chapter describes maintainer level git configuration. + +Tagged branches used in :ref:`Documentation/maintainer/pull-requests.rst +<pullrequests>` should be signed with the developers public GPG key. Signed +tags can be created by passing the ``-u`` flag to ``git tag``. However, +since you would *usually* use the same key for the same project, you can +set it once with +:: + + git config user.signingkey "keyname" + +Alternatively, edit your ``.git/config`` or ``~/.gitconfig`` file by hand: +:: + + [user] + name = Jane Developer + email = jd@domain.org + signingkey = jd@domain.org + +You may need to tell ``git`` to use ``gpg2`` +:: + + [gpg] + program = /path/to/gpg2 + +You may also like to tell ``gpg`` which ``tty`` to use (add to your shell rc file) +:: + + export GPG_TTY=$(tty) diff --git a/Documentation/maintainer/index.rst b/Documentation/maintainer/index.rst new file mode 100644 index 000000000000..2a14916930cb --- /dev/null +++ b/Documentation/maintainer/index.rst @@ -0,0 +1,14 @@ +========================== +Kernel Maintainer Handbook +========================== + +This document is the humble beginning of a manual for kernel maintainers. +There is a lot yet to go here! Please feel free to propose (and write) +additions to this manual. + +.. toctree:: + :maxdepth: 2 + + configure-git + pull-requests + diff --git a/Documentation/maintainer/pull-requests.rst b/Documentation/maintainer/pull-requests.rst new file mode 100644 index 000000000000..a19db3458b56 --- /dev/null +++ b/Documentation/maintainer/pull-requests.rst @@ -0,0 +1,178 @@ +.. _pullrequests: + +Creating Pull Requests +====================== + +This chapter describes how maintainers can create and submit pull requests +to other maintainers. This is useful for transferring changes from one +maintainers tree to another maintainers tree. + +This document was written by Tobin C. Harding (who at that time, was not an +experienced maintainer) primarily from comments made by Greg Kroah-Hartman +and Linus Torvalds on LKML. Suggestions and fixes by Jonathan Corbet and +Mauro Carvalho Chehab. Misrepresentation was unintentional but inevitable, +please direct abuse to Tobin C. Harding <me@tobin.cc>. + +Original email thread:: + + http://lkml.kernel.org/r/20171114110500.GA21175@kroah.com + + +Create Branch +------------- + +To start with you will need to have all the changes you wish to include in +the pull request on a separate branch. Typically you will base this branch +off of a branch in the developers tree whom you intend to send the pull +request to. + +In order to create the pull request you must first tag the branch that you +have just created. It is recommended that you choose a meaningful tag name, +in a way that you and others can understand, even after some time. A good +practice is to include in the name an indicator of the sybsystem of origin +and the target kernel version. + +Greg offers the following. A pull request with miscellaneous stuff for +drivers/char, to be applied at the Kernel version 4.15-rc1 could be named +as ``char-misc-4.15-rc1``. If such tag would be produced from a branch +named ``char-misc-next``, you would be using the following command:: + + git tag -s char-misc-4.15-rc1 char-misc-next + +that will create a signed tag called ``char-misc-4.15-rc1`` based on the +last commit in the ``char-misc-next`` branch, and sign it with your gpg key +(see :ref:`Documentation/maintainer/configure_git.rst <configuregit>`). + +Linus will only accept pull requests based on a signed tag. Other +maintainers may differ. + +When you run the above command ``git`` will drop you into an editor and ask +you to describe the tag. In this case, you are describing a pull request, +so outline what is contained here, why it should be merged, and what, if +any, testing has been done. All of this information will end up in the tag +itself, and then in the merge commit that the maintainer makes if/when they +merge the pull request. So write it up well, as it will be in the kernel +tree for forever. + +As said by Linus:: + + Anyway, at least to me, the important part is the *message*. I want + to understand what I'm pulling, and why I should pull it. I also + want to use that message as the message for the merge, so it should + not just make sense to me, but make sense as a historical record + too. + + Note that if there is something odd about the pull request, that + should very much be in the explanation. If you're touching files + that you don't maintain, explain _why_. I will see it in the + diffstat anyway, and if you didn't mention it, I'll just be extra + suspicious. And when you send me new stuff after the merge window + (or even bug-fixes, but ones that look scary), explain not just + what they do and why they do it, but explain the _timing_. What + happened that this didn't go through the merge window.. + + I will take both what you write in the email pull request _and_ in + the signed tag, so depending on your workflow, you can either + describe your work in the signed tag (which will also automatically + make it into the pull request email), or you can make the signed + tag just a placeholder with nothing interesting in it, and describe + the work later when you actually send me the pull request. + + And yes, I will edit the message. Partly because I tend to do just + trivial formatting (the whole indentation and quoting etc), but + partly because part of the message may make sense for me at pull + time (describing the conflicts and your personal issues for sending + it right now), but may not make sense in the context of a merge + commit message, so I will try to make it all make sense. I will + also fix any speeling mistaeks and bad grammar I notice, + particularly for non-native speakers (but also for native ones + ;^). But I may miss some, or even add some. + + Linus + +Greg gives, as an example pull request:: + + Char/Misc patches for 4.15-rc1 + + Here is the big char/misc patch set for the 4.15-rc1 merge window. + Contained in here is the normal set of new functions added to all + of these crazy drivers, as well as the following brand new + subsystems: + - time_travel_controller: Finally a set of drivers for the + latest time travel bus architecture that provides i/o to + the CPU before it asked for it, allowing uninterrupted + processing + - relativity_shifters: due to the affect that the + time_travel_controllers have on the overall system, there + was a need for a new set of relativity shifter drivers to + accommodate the newly formed black holes that would + threaten to suck CPUs into them. This subsystem handles + this in a way to successfully neutralize the problems. + There is a Kconfig option to force these to be enabled + when needed, so problems should not occur. + + All of these patches have been successfully tested in the latest + linux-next releases, and the original problems that it found have + all been resolved (apologies to anyone living near Canberra for the + lack of the Kconfig options in the earlier versions of the + linux-next tree creations.) + + Signed-off-by: Your-name-here <your_email@domain> + + +The tag message format is just like a git commit id. One line at the top +for a "summary subject" and be sure to sign-off at the bottom. + +Now that you have a local signed tag, you need to push it up to where it +can be retrieved:: + + git push origin char-misc-4.15-rc1 + + +Create Pull Request +------------------- + +The last thing to do is create the pull request message. ``git`` handily +will do this for you with the ``git request-pull`` command, but it needs a +bit of help determining what you want to pull, and on what to base the pull +against (to show the correct changes to be pulled and the diffstat). The +following command(s) will generate a pull request:: + + git request-pull master git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git/ char-misc-4.15-rc1 + +Quoting Greg:: + + This is asking git to compare the difference from the + 'char-misc-4.15-rc1' tag location, to the head of the 'master' + branch (which in my case points to the last location in Linus's + tree that I diverged from, usually a -rc release) and to use the + git:// protocol to pull from. If you wish to use https://, that + can be used here instead as well (but note that some people behind + firewalls will have problems with https git pulls). + + If the char-misc-4.15-rc1 tag is not present in the repo that I am + asking to be pulled from, git will complain saying it is not there, + a handy way to remember to actually push it to a public location. + + The output of 'git request-pull' will contain the location of the + git tree and specific tag to pull from, and the full text + description of that tag (which is why you need to provide good + information in that tag). It will also create a diffstat of the + pull request, and a shortlog of the individual commits that the + pull request will provide. + +Linus responded that he tends to prefer the ``git://`` protocol. Other +maintainers may have different preferences. Also, note that if you are +creating pull requests without a signed tag then ``https://`` may be a +better choice. Please see the original thread for the full discussion. + + +Submit Pull Request +------------------- + +A pull request is submitted in the same way as an ordinary patch. Send as +inline email to the maintainer and CC LKML and any sub-system specific +lists if required. Pull requests to Linus typically have a subject line +something like:: + + [GIT PULL] <subsystem> changes for v4.15-rc1 diff --git a/Documentation/process/kernel-enforcement-statement.rst b/Documentation/process/kernel-enforcement-statement.rst index bfa6a78103d8..6816c12d6956 100644 --- a/Documentation/process/kernel-enforcement-statement.rst +++ b/Documentation/process/kernel-enforcement-statement.rst @@ -68,6 +68,7 @@ we might work for today, have in the past, or will in the future. - Paul Burton - Javier Martinez Canillas - Rob Clark + - Kees Cook (Google) - Jonathan Corbet - Dennis Dalessandro - Vivien Didelot (Savoir-faire Linux) @@ -137,6 +138,7 @@ we might work for today, have in the past, or will in the future. - Anna Schumaker - Jes Sorensen - K.Y. Srinivasan + - David Sterba (SUSE) - Heiko Stuebner - Jiri Kosina (SUSE) - Willy Tarreau @@ -144,6 +146,7 @@ we might work for today, have in the past, or will in the future. - Linus Torvalds - Thierry Reding - Rik van Riel + - Luis R. Rodriguez - Geert Uytterhoeven (Glider bvba) - Eduardo Valentin (Amazon.com) - Daniel Vetter diff --git a/Documentation/process/license-rules.rst b/Documentation/process/license-rules.rst new file mode 100644 index 000000000000..408f77dc6157 --- /dev/null +++ b/Documentation/process/license-rules.rst @@ -0,0 +1,370 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Linux kernel licensing rules +============================ + +The Linux Kernel is provided under the terms of the GNU General Public +License version 2 only (GPL-2.0), as published by the Free Software +Foundation, and provided in the COPYING file. This documentation file is +not meant to replace the COPYING file, but provides a description of how +each source file should be annotated to make the licensing it is governed +under clear and unambiguous. + +The license in the COPYING file applies to the kernel source as a whole, +though individual source files can have a different license which is +required to be compatible with the GPL-2.0:: + + GPL-1.0+ : GNU General Public License v1.0 or later + GPL-2.0+ : GNU General Public License v2.0 or later + LGPL-2.0 : GNU Library General Public License v2 only + LGPL-2.0+ : GNU Library General Public License v2 or later + LGPL-2.1 : GNU Lesser General Public License v2.1 only + LGPL-2.1+ : GNU Lesser General Public License v2.1 or later + +Aside from that, individual files can be provided under a dual license, +e.g. one of the compatible GPL variants and alternatively under a +permissive license like BSD, MIT etc. + +The User-space API (UAPI) header files, which describe the interface of +user-space programs to the kernel are a special case. According to the +note in the kernel COPYING file, the syscall interface is a clear boundary, +which does not extend the GPL requirements to any software which uses it to +communicate with the kernel. Because the UAPI headers must be includable +into any source files which create an executable running on the Linux +kernel, the exception must be documented by a special license expression. + +The common way of expressing the license of a source file is to add the +matching boilerplate text into the top comment of the file. Due to +formatting, typos etc. these "boilerplates" are hard to validate for +tools which are used in the context of license compliance. + +An alternative to boilerplate text is the use of Software Package Data +Exchange (SPDX) license identifiers in each source file. SPDX license +identifiers are machine parsable and precise shorthands for the license +under which the content of the file is contributed. SPDX license +identifiers are managed by the SPDX Workgroup at the Linux Foundation and +have been agreed on by partners throughout the industry, tool vendors, and +legal teams. For further information see https://spdx.org/ + +The Linux kernel requires the precise SPDX identifier in all source files. +The valid identifiers used in the kernel are explained in the section +`License identifiers`_ and have been retrieved from the official SPDX +license list at https://spdx.org/licenses/ along with the license texts. + +License identifier syntax +------------------------- + +1. Placement: + + The SPDX license identifier in kernel files shall be added at the first + possible line in a file which can contain a comment. For the majority + or files this is the first line, except for scripts which require the + '#!PATH_TO_INTERPRETER' in the first line. For those scripts the SPDX + identifier goes into the second line. + +| + +2. Style: + + The SPDX license identifier is added in form of a comment. The comment + style depends on the file type:: + + C source: // SPDX-License-Identifier: <SPDX License Expression> + C header: /* SPDX-License-Identifier: <SPDX License Expression> */ + ASM: /* SPDX-License-Identifier: <SPDX License Expression> */ + scripts: # SPDX-License-Identifier: <SPDX License Expression> + .rst: .. SPDX-License-Identifier: <SPDX License Expression> + .dts{i}: // SPDX-License-Identifier: <SPDX License Expression> + + If a specific tool cannot handle the standard comment style, then the + appropriate comment mechanism which the tool accepts shall be used. This + is the reason for having the "/\* \*/" style comment in C header + files. There was build breakage observed with generated .lds files where + 'ld' failed to parse the C++ comment. This has been fixed by now, but + there are still older assembler tools which cannot handle C++ style + comments. + +| + +3. Syntax: + + A <SPDX License Expression> is either an SPDX short form license + identifier found on the SPDX License List, or the combination of two + SPDX short form license identifiers separated by "WITH" when a license + exception applies. When multiple licenses apply, an expression consists + of keywords "AND", "OR" separating sub-expressions and surrounded by + "(", ")" . + + License identifiers for licenses like [L]GPL with the 'or later' option + are constructed by using a "+" for indicating the 'or later' option.:: + + // SPDX-License-Identifier: GPL-2.0+ + // SPDX-License-Identifier: LGPL-2.1+ + + WITH should be used when there is a modifier to a license needed. + For example, the linux kernel UAPI files use the expression:: + + // SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note + // SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note + + Other examples using WITH exceptions found in the kernel are:: + + // SPDX-License-Identifier: GPL-2.0 WITH mif-exception + // SPDX-License-Identifier: GPL-2.0+ WITH GCC-exception-2.0 + + Exceptions can only be used with particular License identifiers. The + valid License identifiers are listed in the tags of the exception text + file. For details see the point `Exceptions`_ in the chapter `License + identifiers`_. + + OR should be used if the file is dual licensed and only one license is + to be selected. For example, some dtsi files are available under dual + licenses:: + + // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause + + Examples from the kernel for license expressions in dual licensed files:: + + // SPDX-License-Identifier: GPL-2.0 OR MIT + // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause + // SPDX-License-Identifier: GPL-2.0 OR Apache-2.0 + // SPDX-License-Identifier: GPL-2.0 OR MPL-1.1 + // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) OR MIT + // SPDX-License-Identifier: GPL-1.0+ OR BSD-3-Clause OR OpenSSL + + AND should be used if the file has multiple licenses whose terms all + apply to use the file. For example, if code is inherited from another + project and permission has been given to put it in the kernel, but the + original license terms need to remain in effect:: + + // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) AND MIT + + Another other example where both sets of license terms need to be + adhered to is:: + + // SPDX-License-Identifier: GPL-1.0+ AND LGPL-2.1+ + +License identifiers +------------------- + +The licenses currently used, as well as the licenses for code added to the +kernel, can be broken down into: + +1. _`Preferred licenses`: + + Whenever possible these licenses should be used as they are known to be + fully compatible and widely used. These licenses are available from the + directory:: + + LICENSES/preferred/ + + in the kernel source tree. + + The files in this directory contain the full license text and + `Metatags`_. The file names are identical to the SPDX license + identifier which shall be used for the license in source files. + + Examples:: + + LICENSES/preferred/GPL-2.0 + + Contains the GPL version 2 license text and the required metatags:: + + LICENSES/preferred/MIT + + Contains the MIT license text and the required metatags + + _`Metatags`: + + The following meta tags must be available in a license file: + + - Valid-License-Identifier: + + One or more lines which declare which License Identifiers are valid + inside the project to reference this particular license text. Usually + this is a single valid identifier, but e.g. for licenses with the 'or + later' options two identifiers are valid. + + - SPDX-URL: + + The URL of the SPDX page which contains additional information related + to the license. + + - Usage-Guidance: + + Freeform text for usage advice. The text must include correct examples + for the SPDX license identifiers as they should be put into source + files according to the `License identifier syntax`_ guidelines. + + - License-Text: + + All text after this tag is treated as the original license text + + File format examples:: + + Valid-License-Identifier: GPL-2.0 + Valid-License-Identifier: GPL-2.0+ + SPDX-URL: https://spdx.org/licenses/GPL-2.0.html + Usage-Guide: + To use this license in source code, put one of the following SPDX + tag/value pairs into a comment according to the placement + guidelines in the licensing rules documentation. + For 'GNU General Public License (GPL) version 2 only' use: + SPDX-License-Identifier: GPL-2.0 + For 'GNU General Public License (GPL) version 2 or any later version' use: + SPDX-License-Identifier: GPL-2.0+ + License-Text: + Full license text + + :: + + SPDX-License-Identifier: MIT + SPDX-URL: https://spdx.org/licenses/MIT.html + Usage-Guide: + To use this license in source code, put the following SPDX + tag/value pair into a comment according to the placement + guidelines in the licensing rules documentation. + SPDX-License-Identifier: MIT + License-Text: + Full license text + +| + +2. Not recommended licenses: + + These licenses should only be used for existing code or for importing + code from a different project. These licenses are available from the + directory:: + + LICENSES/other/ + + in the kernel source tree. + + The files in this directory contain the full license text and + `Metatags`_. The file names are identical to the SPDX license + identifier which shall be used for the license in source files. + + Examples:: + + LICENSES/other/ISC + + Contains the Internet Systems Consortium license text and the required + metatags:: + + LICENSES/other/ZLib + + Contains the ZLIB license text and the required metatags. + + Metatags: + + The metatag requirements for 'other' licenses are identical to the + requirements of the `Preferred licenses`_. + + File format example:: + + Valid-License-Identifier: ISC + SPDX-URL: https://spdx.org/licenses/ISC.html + Usage-Guide: + Usage of this license in the kernel for new code is discouraged + and it should solely be used for importing code from an already + existing project. + To use this license in source code, put the following SPDX + tag/value pair into a comment according to the placement + guidelines in the licensing rules documentation. + SPDX-License-Identifier: ISC + License-Text: + Full license text + +| + +3. _`Exceptions`: + + Some licenses can be amended with exceptions which grant certain rights + which the original license does not. These exceptions are available + from the directory:: + + LICENSES/exceptions/ + + in the kernel source tree. The files in this directory contain the full + exception text and the required `Exception Metatags`_. + + Examples:: + + LICENSES/exceptions/Linux-syscall-note + + Contains the Linux syscall exception as documented in the COPYING + file of the Linux kernel, which is used for UAPI header files. + e.g. /\* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note \*/:: + + LICENSES/exceptions/GCC-exception-2.0 + + Contains the GCC 'linking exception' which allows to link any binary + independent of its license against the compiled version of a file marked + with this exception. This is required for creating runnable executables + from source code which is not compatible with the GPL. + + _`Exception Metatags`: + + The following meta tags must be available in an exception file: + + - SPDX-Exception-Identifier: + + One exception identifier which can be used with SPDX license + identifiers. + + - SPDX-URL: + + The URL of the SPDX page which contains additional information related + to the exception. + + - SPDX-Licenses: + + A comma separated list of SPDX license identifiers for which the + exception can be used. + + - Usage-Guidance: + + Freeform text for usage advice. The text must be followed by correct + examples for the SPDX license identifiers as they should be put into + source files according to the `License identifier syntax`_ guidelines. + + - Exception-Text: + + All text after this tag is treated as the original exception text + + File format examples:: + + SPDX-Exception-Identifier: Linux-syscall-note + SPDX-URL: https://spdx.org/licenses/Linux-syscall-note.html + SPDX-Licenses: GPL-2.0, GPL-2.0+, GPL-1.0+, LGPL-2.0, LGPL-2.0+, LGPL-2.1, LGPL-2.1+ + Usage-Guidance: + This exception is used together with one of the above SPDX-Licenses + to mark user-space API (uapi) header files so they can be included + into non GPL compliant user-space application code. + To use this exception add it with the keyword WITH to one of the + identifiers in the SPDX-Licenses tag: + SPDX-License-Identifier: <SPDX-License> WITH Linux-syscall-note + Exception-Text: + Full exception text + + :: + + SPDX-Exception-Identifier: GCC-exception-2.0 + SPDX-URL: https://spdx.org/licenses/GCC-exception-2.0.html + SPDX-Licenses: GPL-2.0, GPL-2.0+ + Usage-Guidance: + The "GCC Runtime Library exception 2.0" is used together with one + of the above SPDX-Licenses for code imported from the GCC runtime + library. + To use this exception add it with the keyword WITH to one of the + identifiers in the SPDX-Licenses tag: + SPDX-License-Identifier: <SPDX-License> WITH GCC-exception-2.0 + Exception-Text: + Full exception text + + +All SPDX license identifiers and exceptions must have a corresponding file +in the LICENSE subdirectories. This is required to allow tool +verification (e.g. checkpatch.pl) and to have the licenses ready to read +and extract right from the source, which is recommended by various FOSS +organizations, e.g. the `FSFE REUSE initiative <https://reuse.software/>`_. diff --git a/Documentation/process/submit-checklist.rst b/Documentation/process/submit-checklist.rst index a0d9d34bfb6d..367353c54949 100644 --- a/Documentation/process/submit-checklist.rst +++ b/Documentation/process/submit-checklist.rst @@ -37,7 +37,9 @@ and elsewhere regarding submitting Linux kernel patches. You should be able to justify all violations that remain in your patch. -6) Any new or modified ``CONFIG`` options don't muck up the config menu. +6) Any new or modified ``CONFIG`` options do not muck up the config menu and + default to off unless they meet the exception criteria documented in + ``Documentation/kbuild/kconfig-language.txt`` Menu attributes: default value. 7) All new ``Kconfig`` options have help text. diff --git a/Documentation/security/credentials.rst b/Documentation/security/credentials.rst index 66a2e24939d8..5bb7125faeee 100644 --- a/Documentation/security/credentials.rst +++ b/Documentation/security/credentials.rst @@ -451,6 +451,13 @@ checks and hooks done. Both the current and the proposed sets of credentials are available for this purpose as current_cred() will return the current set still at this point. +When replacing the group list, the new list must be sorted before it +is added to the credential, as a binary search is used to test for +membership. In practice, this means :c:func:`groups_sort` should be +called before :c:func:`set_groups` or :c:func:`set_current_groups`. +:c:func:`groups_sort)` must not be called on a ``struct group_list`` which +is shared as it may permute elements as part of the sorting process +even if the array is already sorted. When the credential set is ready, it should be committed to the current process by calling:: diff --git a/Documentation/security/self-protection.rst b/Documentation/security/self-protection.rst index 60c8bd8b77bf..0f53826c78b9 100644 --- a/Documentation/security/self-protection.rst +++ b/Documentation/security/self-protection.rst @@ -270,6 +270,21 @@ attacks, it is important to defend against exposure of both kernel memory addresses and kernel memory contents (since they may contain kernel addresses or other sensitive things like canary values). +Kernel addresses +---------------- + +Printing kernel addresses to userspace leaks sensitive information about +the kernel memory layout. Care should be exercised when using any printk +specifier that prints the raw address, currently %px, %p[ad], (and %p[sSb] +in certain circumstances [*]). Any file written to using one of these +specifiers should be readable only by privileged processes. + +Kernels 4.14 and older printed the raw address using %p. As of 4.15-rc1 +addresses printed with the specifier %p are hashed before printing. + +[*] If KALLSYMS is enabled and symbol lookup fails, the raw address is +printed. If KALLSYMS is not enabled the raw address is printed. + Unique identifiers ------------------ diff --git a/Documentation/sphinx/kfigure.py b/Documentation/sphinx/kfigure.py index cef4ad19624c..b97228d2cc0e 100644 --- a/Documentation/sphinx/kfigure.py +++ b/Documentation/sphinx/kfigure.py @@ -81,7 +81,7 @@ __version__ = '1.0.0' # ------------- def which(cmd): - """Searches the ``cmd`` in the ``PATH`` enviroment. + """Searches the ``cmd`` in the ``PATH`` environment. This *which* searches the PATH for executable ``cmd`` . First match is returned, if nothing is found, ``None` is returned. @@ -419,7 +419,7 @@ def visit_kernel_render(self, node): tmp_ext = RENDER_MARKUP_EXT.get(srclang, None) if tmp_ext is None: - app.warn('kernel-render: "%s" unknow / include raw.' % (srclang)) + app.warn('kernel-render: "%s" unknown / include raw.' % (srclang)) return if not dot_cmd and tmp_ext == '.dot': @@ -482,7 +482,7 @@ class KernelRender(Figure): srclang = self.arguments[0].strip() if srclang not in RENDER_MARKUP_EXT.keys(): return [self.state_machine.reporter.warning( - 'Unknow source language "%s", use one of: %s.' % ( + 'Unknown source language "%s", use one of: %s.' % ( srclang, ",".join(RENDER_MARKUP_EXT.keys())), line=self.lineno)] diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 694968c7523c..412314eebda6 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -34,6 +34,7 @@ show up in /proc/sys/kernel: - hostname - hotplug - hardlockup_all_cpu_backtrace +- hardlockup_panic - hung_task_panic - hung_task_check_count - hung_task_timeout_secs @@ -313,6 +314,19 @@ will be initiated. 1: on detection capture more debug information. ============================================================== +hardlockup_panic: + +This parameter can be used to control whether the kernel panics +when a hard lockup is detected. + + 0 - don't panic on hard lockup + 1 - panic on hard lockup + +See Documentation/lockup-watchdogs.txt for more information. This can +also be set using the nmi_watchdog kernel parameter. + +============================================================== + hotplug: Path for the hotplug policy agent. @@ -377,7 +391,8 @@ kptr_restrict: This toggle indicates whether restrictions are placed on exposing kernel addresses via /proc and other interfaces. -When kptr_restrict is set to (0), the default, there are no restrictions. +When kptr_restrict is set to 0 (the default) the address is hashed before +printing. (This is the equivalent to %p.) When kptr_restrict is set to (1), kernel pointers printed using the %pK format specifier will be replaced with 0's unless the user has CAP_SYSLOG diff --git a/Documentation/trace/ftrace-uses.rst b/Documentation/trace/ftrace-uses.rst index 8494a801d341..3aed560a12ee 100644 --- a/Documentation/trace/ftrace-uses.rst +++ b/Documentation/trace/ftrace-uses.rst @@ -42,9 +42,9 @@ as well as what protections the callback will perform and not require ftrace to handle. There is only one field that is needed to be set when registering -an ftrace_ops with ftrace:: +an ftrace_ops with ftrace: -.. code-block: c +.. code-block:: c struct ftrace_ops ops = { .func = my_callback_func, @@ -81,12 +81,12 @@ may take some time to finish. The callback function ===================== -The prototype of the callback function is as follows (as of v4.14):: +The prototype of the callback function is as follows (as of v4.14): -.. code-block: c +.. code-block:: c - void callback_func(unsigned long ip, unsigned long parent_ip, - struct ftrace_ops *op, struct pt_regs *regs); + void callback_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs); @ip This is the instruction pointer of the function that is being traced. @@ -176,10 +176,10 @@ Filtering which functions to trace If a callback is only to be called from specific functions, a filter must be set up. The filters are added by name, or ip if it is known. -.. code-block: c +.. code-block:: c - int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf, - int len, int reset); + int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf, + int len, int reset); @ops The ops to set the filter with @@ -202,9 +202,9 @@ See Filter Commands in :file:`Documentation/trace/ftrace.txt`. To just trace the schedule function:: -.. code-block: c +.. code-block:: c - ret = ftrace_set_filter(&ops, "schedule", strlen("schedule"), 0); + ret = ftrace_set_filter(&ops, "schedule", strlen("schedule"), 0); To add more functions, call the ftrace_set_filter() more than once with the @reset parameter set to zero. To remove the current filter set and replace it @@ -212,17 +212,17 @@ with new functions defined by @buf, have @reset be non-zero. To remove all the filtered functions and trace all functions:: -.. code-block: c +.. code-block:: c - ret = ftrace_set_filter(&ops, NULL, 0, 1); + ret = ftrace_set_filter(&ops, NULL, 0, 1); Sometimes more than one function has the same name. To trace just a specific function in this case, ftrace_set_filter_ip() can be used. -.. code-block: c +.. code-block:: c - ret = ftrace_set_filter_ip(&ops, ip, 0, 0); + ret = ftrace_set_filter_ip(&ops, ip, 0, 0); Although the ip must be the address where the call to fentry or mcount is located in the function. This function is used by perf and kprobes that @@ -237,10 +237,10 @@ be called by any function. An empty "notrace" list means to allow all functions defined by the filter to be traced. -.. code-block: c +.. code-block:: c - int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf, - int len, int reset); + int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf, + int len, int reset); This takes the same parameters as ftrace_set_filter() but will add the functions it finds to not be traced. This is a separate list from the @@ -251,7 +251,7 @@ that match @buf to it. Clearing the "notrace" list is the same as clearing the filter list -.. code-block: c +.. code-block:: c ret = ftrace_set_notrace(&ops, NULL, 0, 1); @@ -264,29 +264,29 @@ If a filter is in place, and the @reset is non-zero, and @buf contains a matching glob to functions, the switch will happen during the time of the ftrace_set_filter() call. At no time will all functions call the callback. -.. code-block: c +.. code-block:: c - ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); + ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); - register_ftrace_function(&ops); + register_ftrace_function(&ops); - msleep(10); + msleep(10); - ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 1); + ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 1); is not the same as: -.. code-block: c +.. code-block:: c - ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); + ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); - register_ftrace_function(&ops); + register_ftrace_function(&ops); - msleep(10); + msleep(10); - ftrace_set_filter(&ops, NULL, 0, 1); + ftrace_set_filter(&ops, NULL, 0, 1); - ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 0); + ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 0); As the latter will have a short time where all functions will call the callback, between the time of the reset, and the time of the diff --git a/Documentation/usb/chipidea.txt b/Documentation/usb/chipidea.txt index edf7cdfddc88..d1eedc01b00a 100644 --- a/Documentation/usb/chipidea.txt +++ b/Documentation/usb/chipidea.txt @@ -23,13 +23,13 @@ cat /sys/kernel/debug/ci_hdrc.0/registers 2) Connect 2 boards with usb cable with one end is micro A plug, the other end is micro B plug. - The A-device(with micro A plug inserted) should enumrate B-device. + The A-device(with micro A plug inserted) should enumerate B-device. 3) Role switch On B-device: echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req - B-device should take host role and enumrate A-device. + B-device should take host role and enumerate A-device. 4) A-device switch back to host. On B-device: @@ -40,13 +40,13 @@ cat /sys/kernel/debug/ci_hdrc.0/registers side by answering the polling from B-Host, this can be done on A-device: echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req - A-device should switch back to host and enumrate B-device. + A-device should switch back to host and enumerate B-device. 5) Remove B-device(unplug micro B plug) and insert again in 10 seconds, - A-device should enumrate B-device again. + A-device should enumerate B-device again. 6) Remove B-device(unplug micro B plug) and insert again after 10 seconds, - A-device should NOT enumrate B-device. + A-device should NOT enumerate B-device. if A-device wants to use bus: On A-device: @@ -67,7 +67,7 @@ cat /sys/kernel/debug/ci_hdrc.0/registers On B-device: echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req - A-device should resume usb bus and enumrate B-device. + A-device should resume usb bus and enumerate B-device. 1.3 Reference document ---------------------- diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt index 6ae89a9edf2a..e912d7eee769 100644 --- a/Documentation/vm/hwpoison.txt +++ b/Documentation/vm/hwpoison.txt @@ -104,7 +104,7 @@ madvise(MADV_HWPOISON, ....) hwpoison-inject module through debugfs -/sys/debug/hwpoison/ +/sys/kernel/debug/hwpoison/ corrupt-pfn diff --git a/Documentation/w1/w1.generic b/Documentation/w1/w1.generic index b3ffaf8cfab2..c51b1ab012d0 100644 --- a/Documentation/w1/w1.generic +++ b/Documentation/w1/w1.generic @@ -76,7 +76,7 @@ See struct w1_bus_master definition in w1.h for details. w1 master sysfs interface ------------------------------------------------------------------ -<xx-xxxxxxxxxxxxx> - A directory for a found device. The format is family-serial +<xx-xxxxxxxxxxxx> - A directory for a found device. The format is family-serial bus - (standard) symlink to the w1 bus driver - (standard) symlink to the w1 driver w1_master_add - (rw) manually register a slave device |