From fd89cfb8718753459fcea3fe6103d19de5e86c9b Mon Sep 17 00:00:00 2001 From: Thomas Renninger Date: Fri, 6 Aug 2010 16:11:01 +0200 Subject: Dynamic Debug: Split out query string parsing/setup from proc_write The parsing and applying of dynamic debug strings is not only useful for /sys/../dynamic_debug/control write access, but can also be used for boot parameter parsing. The boot parameter is introduced in a follow up patch. Signed-off-by: Thomas Renninger Acked-by: jbaron@redhat.com Acked-by: Pekka Enberg Signed-off-by: Greg Kroah-Hartman --- lib/dynamic_debug.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) (limited to 'lib') diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 02afc253372..84d103c474e 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -429,6 +429,27 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp, return 0; } +static int ddebug_exec_query(char *query_string) +{ + unsigned int flags = 0, mask = 0; + struct ddebug_query query; +#define MAXWORDS 9 + int nwords; + char *words[MAXWORDS]; + + nwords = ddebug_tokenize(query_string, words, MAXWORDS); + if (nwords <= 0) + return -EINVAL; + if (ddebug_parse_query(words, nwords-1, &query)) + return -EINVAL; + if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) + return -EINVAL; + + /* actually go and implement the change */ + ddebug_change(&query, flags, mask); + return 0; +} + /* * File_ops->write method for /dynamic_debug/conrol. Gathers the * command text from userspace, parses and executes it. @@ -436,12 +457,8 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp, static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf, size_t len, loff_t *offp) { - unsigned int flags = 0, mask = 0; - struct ddebug_query query; -#define MAXWORDS 9 - int nwords; - char *words[MAXWORDS]; char tmpbuf[256]; + int ret; if (len == 0) return 0; @@ -455,16 +472,9 @@ static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf, printk(KERN_INFO "%s: read %d bytes from userspace\n", __func__, (int)len); - nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS); - if (nwords <= 0) - return -EINVAL; - if (ddebug_parse_query(words, nwords-1, &query)) - return -EINVAL; - if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) - return -EINVAL; - - /* actually go and implement the change */ - ddebug_change(&query, flags, mask); + ret = ddebug_exec_query(tmpbuf); + if (ret) + return ret; *offp += len; return len; -- cgit v1.2.3 From a648ec05bb950fae2f35d0490ddd6cf15010af72 Mon Sep 17 00:00:00 2001 From: Thomas Renninger Date: Fri, 6 Aug 2010 16:11:02 +0200 Subject: Dynamic Debug: Introduce ddebug_query= boot parameter Dynamic debug lacks the ability to enable debug messages at boot time. One could patch initramfs or service startup scripts to write to /sys/../dynamic_debug/control, but this sucks. This patch makes it possible to pass a query in the same format one can write to /sys/../dynamic_debug/control via boot param. When dynamic debug gets initialized, this query will automatically be applied. Signed-off-by: Thomas Renninger Acked-by: jbaron@redhat.com Acked-by: Pekka Enberg Signed-off-by: Greg Kroah-Hartman --- Documentation/dynamic-debug-howto.txt | 22 +++++++++++++++++++++- Documentation/kernel-parameters.txt | 7 ++++++- lib/dynamic_debug.c | 25 +++++++++++++++++++++++++ 3 files changed, 52 insertions(+), 2 deletions(-) (limited to 'lib') diff --git a/Documentation/dynamic-debug-howto.txt b/Documentation/dynamic-debug-howto.txt index 674c5663d34..58ea64a9616 100644 --- a/Documentation/dynamic-debug-howto.txt +++ b/Documentation/dynamic-debug-howto.txt @@ -24,7 +24,7 @@ Dynamic debug has even more useful features: read to display the complete list of known debug statements, to help guide you Controlling dynamic debug Behaviour -=============================== +=================================== The behaviour of pr_debug()/dev_debug()s are controlled via writing to a control file in the 'debugfs' filesystem. Thus, you must first mount the debugfs @@ -212,6 +212,26 @@ Note the regexp ^[-+=][scp]+$ matches a flags specification. Note also that there is no convenient syntax to remove all the flags at once, you need to use "-psc". + +Debug messages during boot process +================================== + +To be able to activate debug messages during the boot process, +even before userspace and debugfs exists, use the boot parameter: +ddebug_query="QUERY" + +QUERY follows the syntax described above, but must not exceed 1023 +characters. The enablement of debug messages is done as an arch_initcall. +Thus you can enable debug messages in all code processed after this +arch_initcall via this boot parameter. +On an x86 system for example ACPI enablement is a subsys_initcall and +ddebug_query="file ec.c +p" +will show early Embedded Controller transactions during ACPI setup if +your machine (typically a laptop) has an Embedded Controller. +PCI (or other devices) initialization also is a hot candidate for using +this boot parameter for debugging purposes. + + Examples ======== diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 8dd7248508a..3d854c9ae53 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -43,10 +43,11 @@ parameter is applicable: AVR32 AVR32 architecture is enabled. AX25 Appropriate AX.25 support is enabled. BLACKFIN Blackfin architecture is enabled. - DRM Direct Rendering Management support is enabled. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled EFI EFI Partitioning (GPT) is enabled EIDE EIDE/ATAPI support is enabled. + DRM Direct Rendering Management support is enabled. + DYNAMIC_DEBUG Build in debug messages and enable them at runtime FB The frame buffer device is enabled. GCOV GCOV profiling is enabled. HW Appropriate hardware is enabled. @@ -570,6 +571,10 @@ and is between 256 and 4096 characters. It is defined in the file Format: , See also Documentation/input/joystick-parport.txt + ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot + time. See Documentation/dynamic-debug-howto.txt for + details. + debug [KNL] Enable kernel debugging (events log level). debug_locks_verbose= diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 84d103c474e..44ce66bdb21 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -450,6 +450,19 @@ static int ddebug_exec_query(char *query_string) return 0; } +static __initdata char ddebug_setup_string[1024]; +static __init int ddebug_setup_query(char *str) +{ + if (strlen(str) >= 1024) { + pr_warning("ddebug boot param string too large\n"); + return 0; + } + strcpy(ddebug_setup_string, str); + return 1; +} + +__setup("ddebug_query=", ddebug_setup_query); + /* * File_ops->write method for /dynamic_debug/conrol. Gathers the * command text from userspace, parses and executes it. @@ -769,6 +782,18 @@ static int __init dynamic_debug_init(void) } ret = ddebug_add_module(iter_start, n, modname); } + + /* ddebug_query boot param got passed -> set it up */ + if (ddebug_setup_string[0] != '\0') { + ret = ddebug_exec_query(ddebug_setup_string); + if (ret) + pr_warning("Invalid ddebug boot param %s", + ddebug_setup_string); + else + pr_info("ddebug initialized with string %s", + ddebug_setup_string); + } + out_free: if (ret) { ddebug_remove_all_tables(); -- cgit v1.2.3 From 6a5c083de2f5fbf89a4b0a251be2c2205434d7ea Mon Sep 17 00:00:00 2001 From: Thomas Renninger Date: Fri, 6 Aug 2010 16:11:03 +0200 Subject: Dynamic Debug: Initialize dynamic debug earlier via arch_initcall Having the ddebug_query= boot parameter it makes sense to set up dynamic debug as soon as possible. I expect sysfs files cannot be set up via an arch_initcall, because this one is even before fs_initcall. Therefore I splitted the dynamic_debug_init function into an early one and a later one providing /sys/../dynamic_debug/control file. Possibly dynamic_debug can be initialized even earlier, not sure whether this still makes sense then. I picked up arch_initcall as it covers quite a lot already. Dynamic debug needs to allocate memory, therefore it's not easily possible to set it up even before the command line gets parsed. Therefore the boot param query string is stored in a temp string which is applied when dynamic debug gets set up. This has been tested with ddebug_query="file ec.c +p" and I could retrieve pr_debug() messages early at boot during ACPI setup: ACPI: EC: Look up EC in DSDT ACPI: EC: ---> status = 0x08 ACPI: EC: transaction start ACPI: EC: <--- command = 0x80 ACPI: EC: ~~~> interrupt ACPI: EC: ---> status = 0x08 ACPI: EC: <--- data = 0xa4 ... ACPI: Interpreter enabled ACPI: (supports S0 S3 S4 S5) ACPI: Using IOAPIC for interrupt routing ACPI: EC: ---> status = 0x00 ACPI: EC: transaction start ACPI: EC: <--- command = 0x80 Signed-off-by: Thomas Renninger Acked-by: jbaron@redhat.com Acked-by: Pekka Enberg CC: linux-acpi@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- lib/dynamic_debug.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) (limited to 'lib') diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 44ce66bdb21..a687d902daa 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -748,13 +748,14 @@ static void ddebug_remove_all_tables(void) mutex_unlock(&ddebug_lock); } -static int __init dynamic_debug_init(void) +static __initdata int ddebug_init_success; + +static int __init dynamic_debug_init_debugfs(void) { struct dentry *dir, *file; - struct _ddebug *iter, *iter_start; - const char *modname = NULL; - int ret = 0; - int n = 0; + + if (!ddebug_init_success) + return -ENODEV; dir = debugfs_create_dir("dynamic_debug", NULL); if (!dir) @@ -765,6 +766,16 @@ static int __init dynamic_debug_init(void) debugfs_remove(dir); return -ENOMEM; } + return 0; +} + +static int __init dynamic_debug_init(void) +{ + struct _ddebug *iter, *iter_start; + const char *modname = NULL; + int ret = 0; + int n = 0; + if (__start___verbose != __stop___verbose) { iter = __start___verbose; modname = iter->modname; @@ -795,11 +806,13 @@ static int __init dynamic_debug_init(void) } out_free: - if (ret) { + if (ret) ddebug_remove_all_tables(); - debugfs_remove(dir); - debugfs_remove(file); - } + else + ddebug_init_success = 1; return 0; } -module_init(dynamic_debug_init); +/* Allow early initialization for boot messages via boot param */ +arch_initcall(dynamic_debug_init); +/* Debugfs setup must be done later */ +module_init(dynamic_debug_init_debugfs); -- cgit v1.2.3 From c25d1dfbd403209025df41a737f82ce8f43d93f5 Mon Sep 17 00:00:00 2001 From: Robin Holt Date: Wed, 29 Sep 2010 14:00:54 -0500 Subject: kobject: Introduce kset_find_obj_hinted. One call chain getting to kset_find_obj is: link_mem_sections() find_mem_section() kset_find_obj() This is done during boot. The memory sections were added in a linearly increasing order and link_mem_sections tends to utilize them in that same linear order. Introduce a kset_find_obj_hinted which is passed the result of the previous kset_find_obj which it uses for a quick "is the next object our desired object" check before falling back to the old behavior. Signed-off-by: Robin Holt To: Robert P. J. Day Reviewed-by: KAMEZAWA Hiroyuki Signed-off-by: Greg Kroah-Hartman --- include/linux/kobject.h | 2 ++ lib/kobject.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) (limited to 'lib') diff --git a/include/linux/kobject.h b/include/linux/kobject.h index 7950a37a714..8f6d1215104 100644 --- a/include/linux/kobject.h +++ b/include/linux/kobject.h @@ -191,6 +191,8 @@ static inline struct kobj_type *get_ktype(struct kobject *kobj) } extern struct kobject *kset_find_obj(struct kset *, const char *); +extern struct kobject *kset_find_obj_hinted(struct kset *, const char *, + struct kobject *); /* The global /sys/kernel/ kobject for people to chain off of */ extern struct kobject *kernel_kobj; diff --git a/lib/kobject.c b/lib/kobject.c index f07c57252e8..82dc34c095c 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -745,18 +745,57 @@ void kset_unregister(struct kset *k) * take a reference and return the object. */ struct kobject *kset_find_obj(struct kset *kset, const char *name) +{ + return kset_find_obj_hinted(kset, name, NULL); +} + +/** + * kset_find_obj_hinted - search for object in kset given a predecessor hint. + * @kset: kset we're looking in. + * @name: object's name. + * @hint: hint to possible object's predecessor. + * + * Check the hint's next object and if it is a match return it directly, + * otherwise, fall back to the behavior of kset_find_obj(). Either way + * a reference for the returned object is held and the reference on the + * hinted object is released. + */ +struct kobject *kset_find_obj_hinted(struct kset *kset, const char *name, + struct kobject *hint) { struct kobject *k; struct kobject *ret = NULL; spin_lock(&kset->list_lock); + + if (!hint) + goto slow_search; + + /* end of list detection */ + if (hint->entry.next == kset->list.next) + goto slow_search; + + k = container_of(hint->entry.next, struct kobject, entry); + if (!kobject_name(k) || strcmp(kobject_name(k), name)) + goto slow_search; + + ret = kobject_get(k); + goto unlock_exit; + +slow_search: list_for_each_entry(k, &kset->list, entry) { if (kobject_name(k) && !strcmp(kobject_name(k), name)) { ret = kobject_get(k); break; } } + +unlock_exit: spin_unlock(&kset->list_lock); + + if (hint) + kobject_put(hint); + return ret; } -- cgit v1.2.3