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2015-01-09kernfs: Fix kernfs_name_compareRasmus Villemoes1-4/+8
Returning a difference from a comparison functions is usually wrong (see acbbe6fbb240 "kcmp: fix standard comparison bug" for the long story). Here there is the additional twist that if the void pointers ns and kn->ns happen to differ by a multiple of 2^32, kernfs_name_compare returns 0, falsely reporting a match to the caller. Technically 'hash - kn->hash' is ok since the hashes are restricted to 31 bits, but it's better to avoid that subtlety. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-12-17vm_area_operations: kill ->migrate()Al Viro1-22/+0
the only instance this method has ever grown was one in kernfs - one that call ->migrate() of another vm_ops if it exists. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-14Merge tag 'driver-core-3.19-rc1' of ↵Linus Torvalds1-23/+50
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core update from Greg KH: "Here's the set of driver core patches for 3.19-rc1. They are dominated by the removal of the .owner field in platform drivers. They touch a lot of files, but they are "simple" changes, just removing a line in a structure. Other than that, a few minor driver core and debugfs changes. There are some ath9k patches coming in through this tree that have been acked by the wireless maintainers as they relied on the debugfs changes. Everything has been in linux-next for a while" * tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (324 commits) Revert "ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries" fs: debugfs: add forward declaration for struct device type firmware class: Deletion of an unnecessary check before the function call "vunmap" firmware loader: fix hung task warning dump devcoredump: provide a one-way disable function device: Add dev_<level>_once variants ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries ath: use seq_file api for ath9k debugfs files debugfs: add helper function to create device related seq_file drivers/base: cacheinfo: remove noisy error boot message Revert "core: platform: add warning if driver has no owner" drivers: base: support cpu cache information interface to userspace via sysfs drivers: base: add cpu_device_create to support per-cpu devices topology: replace custom attribute macros with standard DEVICE_ATTR* cpumask: factor out show_cpumap into separate helper function driver core: Fix unbalanced device reference in drivers_probe driver core: fix race with userland in device_add() sysfs/kernfs: make read requests on pre-alloc files use the buffer. sysfs/kernfs: allow attributes to request write buffer be pre-allocated. fs: sysfs: return EGBIG on write if offset is larger than file size ...
2014-11-19switch d_materialise_unique() users to d_splice_alias()Al Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-07sysfs/kernfs: make read requests on pre-alloc files use the buffer.NeilBrown1-9/+21
To match the previous patch which used the pre-alloc buffer for writes, this patch causes reads to use the same buffer. This is not strictly necessary as the current seq_read() will allocate on first read, so user-space can trigger the required pre-alloc. But consistency is valuable. The read function is somewhat simpler than seq_read() and, for example, does not support reading from an offset into the file: reads must be at the start of the file. As seq_read() does not use the prealloc buffer, ->seq_show is incompatible with ->prealloc and caused an EINVAL return from open(). sysfs code which calls into kernfs always chooses the correct function. As the buffer is shared with writes and other reads, the mutex is extended to cover the copy_to_user. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-07sysfs/kernfs: allow attributes to request write buffer be pre-allocated.NeilBrown1-15/+30
md/raid allows metadata management to be performed in user-space. A various times, particularly on device failure, the metadata needs to be updated before further writes can be permitted. This means that the user-space program which updates metadata much not block on writeout, and so must not allocate memory. mlockall(MCL_CURRENT|MCL_FUTURE) and pre-allocation can avoid all memory allocation issues for user-memory, but that does not help kernel memory. Several kernel objects can be pre-allocated. e.g. files opened before any writes to the array are permitted. However some kernel allocation happens in places that cannot be pre-allocated. In particular, writes to sysfs files (to tell md that it can now allow writes to the array) allocate a buffer using GFP_KERNEL. This patch allows attributes to be marked as "PREALLOC". In that case the maximal buffer is allocated when the file is opened, and then used on each write instead of allocating a new buffer. As the same buffer is now shared for all writes on the same file description, the mutex is extended to cover full use of the buffer including the copy_from_user(). The new __ATTR_PREALLOC() 'or's a new flag in to the 'mode', which is inspected by sysfs_add_file_mode_ns() to determine if the file should be marked as requiring prealloc. Despite the comment, we *do* use ->seq_show together with ->prealloc in this patch. The next patch fixes that. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-10-09vfs: Remove unnecessary calls of check_submounts_and_dropEric W. Biederman1-11/+0
Now that check_submounts_and_drop can not fail and is called from d_invalidate there is no longer a need to call check_submounts_and_drom from filesystem d_revalidate methods so remove it. Reviewed-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-07-21Merge 3.16-rc6 into driver-core-nextGreg Kroah-Hartman1-0/+30
We want the platform changes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-10Merge branch 'for-3.16-fixes' of ↵Linus Torvalds1-0/+30
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup fixes from Tejun Heo: "Mostly fixes for the fallouts from the recent cgroup core changes. The decoupled nature of cgroup dynamic hierarchy management (hierarchies are created dynamically on mount but may or may not be reused once unmounted depending on remaining usages) led to more ugliness being added to kernfs. Hopefully, this is the last of it" * 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cpuset: break kernfs active protection in cpuset_write_resmask() cgroup: fix a race between cgroup_mount() and cgroup_kill_sb() kernfs: introduce kernfs_pin_sb() cgroup: fix mount failure in a corner case cpuset,mempolicy: fix sleeping function called from invalid context cgroup: fix broken css_has_online_children()
2014-07-09kernfs: kernel-doc warning fixFabian Frederick1-1/+1
s/static_name/name_is_static Signed-off-by: Fabian Frederick <fabf@skynet.be> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-02kernfs: kernfs_notify() must be useable from non-sleepable contextsTejun Heo1-14/+55
d911d9874801 ("kernfs: make kernfs_notify() trigger inotify events too") added fsnotify triggering to kernfs_notify() which requires a sleepable context. There are already existing users of kernfs_notify() which invoke it from an atomic context and in general it's silly to require a sleepable context for triggering a notification. The following is an invalid context bug triggerd by md invoking sysfs_notify() from IO completion path. BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586 in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1 2 locks held by swapper/1/0: #0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>] virtblk_done+0x42/0xe0 [virtio_blk] #1: (&(&bitmap->counts.lock)->rlock){-.....}, at: [<ffffffff81633718>] bitmap_endwrite+0x68/0x240 irq event stamp: 33518 hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230 hardirqs last disabled at (33516): [<ffffffff818122ed>] common_interrupt+0x6d/0x72 softirqs last enabled at (33518): [<ffffffff810a1272>] _local_bh_enable+0x22/0x50 softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000000 f90db13964f4ee05 ffff88007d403b80 ffffffff81807b4c 0000000000000000 ffff88007d403ba8 ffffffff810d4f14 0000000000000000 0000000000441800 ffff880078fa1780 ffff88007d403c38 ffffffff8180caf2 Call Trace: <IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66 [<ffffffff810d4f14>] __might_sleep+0x184/0x240 [<ffffffff8180caf2>] mutex_lock_nested+0x42/0x440 [<ffffffff812d76a0>] kernfs_notify+0x90/0x150 [<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240 [<ffffffffa00de863>] close_write+0x93/0xb0 [raid1] [<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1] [<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1] [<ffffffff813acb8b>] bio_endio+0x6b/0xa0 [<ffffffff813b46c4>] blk_update_request+0x94/0x420 [<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70 [<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk] [<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120 [<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30 [<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk] [<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring] [<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340 [<ffffffff8111647d>] handle_irq_event+0x3d/0x60 [<ffffffff81119436>] handle_edge_irq+0x66/0x130 [<ffffffff8101c3e4>] handle_irq+0x84/0x150 [<ffffffff818146ad>] do_IRQ+0x4d/0xe0 [<ffffffff818122f2>] common_interrupt+0x72/0x72 <EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10 [<ffffffff81025454>] default_idle+0x24/0x230 [<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20 [<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0 [<ffffffff8104df1b>] start_secondary+0x25b/0x300 This patch fixes it by punting the notification delivery through a work item. This ends up adding an extra pointer to kernfs_elem_attr enlarging kernfs_node by a pointer, which is not ideal but not a very big deal either. If this turns out to be an actual issue, we can move kernfs_elem_attr->size to kernfs_node->iattr later. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Cc: Jens Axboe <axboe@kernel.dk> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-06-30kernfs: introduce kernfs_pin_sb()Li Zefan1-0/+30
kernfs_pin_sb() tries to get a refcnt of the superblock. This will be used by cgroupfs. v2: - make kernfs_pin_sb() return the superblock. - drop kernfs_drop_sb(). tj: Updated the comment a bit. [ This is a prerequisite for a bugfix. ] Cc: <stable@vger.kernel.org> # 3.15 Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-05-27kernfs: move the last knowledge of sysfs out from kernfsJianyu Zhan1-5/+6
There is still one residue of sysfs remaining: the sb_magic SYSFS_MAGIC. However this should be kernfs user specific, so this patch moves it out. Kerrnfs user should specify their magic number while mouting. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-23Merge 3.15-rc6 into driver-core-nextGreg Kroah-Hartman1-7/+10
We want the kernfs fixes in this branch as well for testing. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-13kernfs, sysfs, cgroup: restrict extra perm check on open to sysfsTejun Heo1-7/+10
The kernfs open method - kernfs_fop_open() - inherited extra permission checks from sysfs. While the vfs layer allows ignoring the read/write permissions checks if the issuer has CAP_DAC_OVERRIDE, sysfs explicitly denied open regardless of the cap if the file doesn't have any of the UGO perms of the requested access or doesn't implement the requested operation. It can be debated whether this was a good idea or not but the behavior is too subtle and dangerous to change at this point. After cgroup got converted to kernfs, this extra perm check also got applied to cgroup breaking libcgroup which opens write-only files with O_RDWR as root. This patch gates the extra open permission check with a new flag KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK and enables it for sysfs. For sysfs, nothing changes. For cgroup, root now can perform any operation regardless of the permissions as it was before kernfs conversion. Note that kernfs still fails unimplemented operations with -EINVAL. While at it, add comments explaining KERNFS_ROOT flags. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Andrey Wagin <avagin@gmail.com> Tested-by: Andrey Wagin <avagin@gmail.com> Cc: Li Zefan <lizefan@huawei.com> References: http://lkml.kernel.org/g/CANaxB-xUm3rJ-Cbp72q-rQJO5mZe1qK6qXsQM=vh0U8upJ44+A@mail.gmail.com Fixes: 2bd59d48ebfb ("cgroup: convert to kernfs") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-27Merge 3.15-rc3 into staging-nextGreg Kroah-Hartman2-3/+8
2014-04-25kernfs: add back missing error check in kernfs_fop_mmap()Tejun Heo1-0/+2
While updating how mmap enabled kernfs files are handled by lockdep, 9b2db6e18945 ("sysfs: bail early from kernfs_file_mmap() to avoid spurious lockdep warning") inadvertently dropped error return check from kernfs_file_mmap(). The intention was just dropping "if (ops->mmap)" check as the control won't reach the point if the mmap callback isn't implemented, but I mistakenly removed the error return check together with it. This led to Xorg crash on i810 which was reported and bisected to the commit and then to the specific change by Tobias. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-bisected-by: Tobias Powalowski <tobias.powalowski@googlemail.com> Tested-by: Tobias Powalowski <tobias.powalowski@googlemail.com> References: http://lkml.kernel.org/g/533D01BD.1010200@googlemail.com Cc: stable <stable@vger.kernel.org> # 3.14 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-25kernfs: fix a subdir count leakJianyu Zhan1-3/+6
Currently kernfs_link_sibling() increates parent->dir.subdirs before adding the node into parent's chidren rb tree. Because it is possible that kernfs_link_sibling() couldn't find a suitable slot and bail out, this leads to a mismatch between elevated subdir count with actual children node numbers. This patches fix this problem, by moving the subdir accouting after the actual addtion happening. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-25kernfs: make kernfs_notify() trigger inotify events tooTejun Heo1-6/+35
kernfs_notify() is used to indicate either new data is available or the content of a file has changed. It currently only triggers poll which may not be the most convenient to monitor especially when there are a lot to monitor. Let's hook it up to fsnotify too so that the events can be monitored via inotify too. fsnotify_modify() requires file * but kernfs_notify() doesn't have any specific file associated; however, we can walk all super_blocks associated with a kernfs_root and as kernfs always associate one ino with inode and one dentry with an inode, it's trivial to look up the dentry associated with a given kernfs_node. As any active monitor would pin dentry, just looking up existing dentry is enough. This patch looks up the dentry associated with the specified kernfs_node and generates events equivalent to fsnotify_modify(). Note that as fsnotify doesn't provide fsnotify_modify() equivalent which can be called with dentry, kernfs_notify() directly calls fsnotify_parent() and fsnotify(). It might be better to add a wrapper in fsnotify.h instead. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: John McCutchan <john@johnmccutchan.com> Cc: Robert Love <rlove@rlove.org> Cc: Eric Paris <eparis@parisplace.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-25kernfs: implement kernfs_root->supers listTejun Heo3-0/+17
Currently, there's no way to find out which super_blocks are associated with a given kernfs_root. Let's implement it - the planned inotify extension to kernfs_notify() needs it. Make kernfs_super_info point back to the super_block and chain it at kernfs_root->supers. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-16kernfs: protect lazy kernfs_iattrs allocation with mutexTejun Heo1-4/+10
kernfs_iattrs is allocated lazily when operations which require it take place; unfortunately, the lazy allocation and returning weren't properly synchronized and when there are multiple concurrent operations, it might end up returning kernfs_iattrs which hasn't finished initialization yet or different copies to different callers. Fix it by synchronizing with a mutex. This can be smarter with memory barriers but let's go there if it actually turns out to be necessary. Signed-off-by: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/g/533ABA32.9080602@oracle.com Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: stable@vger.kernel.org # 3.14 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-03Merge branch 'akpm' (incoming from Andrew)Linus Torvalds1-1/+1
Merge first patch-bomb from Andrew Morton: - Various misc bits - kmemleak fixes - small befs, codafs, cifs, efs, freexxfs, hfsplus, minixfs, reiserfs things - fanotify - I appear to have become SuperH maintainer - ocfs2 updates - direct-io tweaks - a bit of the MM queue - printk updates - MAINTAINERS maintenance - some backlight things - lib/ updates - checkpatch updates - the rtc queue - nilfs2 updates - Small Documentation/ updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (237 commits) Documentation/SubmittingPatches: remove references to patch-scripts Documentation/SubmittingPatches: update some dead URLs Documentation/filesystems/ntfs.txt: remove changelog reference Documentation/kmemleak.txt: updates fs/reiserfs/super.c: add __init to init_inodecache fs/reiserfs: move prototype declaration to header file fs/hfsplus/attributes.c: add __init to hfsplus_create_attr_tree_cache() fs/hfsplus/extents.c: fix concurrent acess of alloc_blocks fs/hfsplus/extents.c: remove unused variable in hfsplus_get_block nilfs2: update project's web site in nilfs2.txt nilfs2: update MAINTAINERS file entries fix nilfs2: verify metadata sizes read from disk nilfs2: add FITRIM ioctl support for nilfs2 nilfs2: add nilfs_sufile_trim_fs to trim clean segs nilfs2: implementation of NILFS_IOCTL_SET_SUINFO ioctl nilfs2: add nilfs_sufile_set_suinfo to update segment usage nilfs2: add struct nilfs_suinfo_update and flags nilfs2: update MAINTAINERS file entries fs/coda/inode.c: add __init to init_inodecache() BEFS: logging cleanup ...
2014-04-03mm + fs: store shadow entries in page cacheJohannes Weiner1-1/+1
Reclaim will be leaving shadow entries in the page cache radix tree upon evicting the real page. As those pages are found from the LRU, an iput() can lead to the inode being freed concurrently. At this point, reclaim must no longer install shadow pages because the inode freeing code needs to ensure the page tree is really empty. Add an address_space flag, AS_EXITING, that the inode freeing code sets under the tree lock before doing the final truncate. Reclaim will check for this flag before installing shadow pages. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bob Liu <bob.liu@oracle.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Metin Doslu <metin@citusdata.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ozgun Erdogan <ozgun@citusdata.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <klamm@yandex-team.ru> Cc: Ryan Mallon <rmallon@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-03Merge branch 'for-3.15' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: "A lot updates for cgroup: - The biggest one is cgroup's conversion to kernfs. cgroup took after the long abandoned vfs-entangled sysfs implementation and made it even more convoluted over time. cgroup's internal objects were fused with vfs objects which also brought in vfs locking and object lifetime rules. Naturally, there are places where vfs rules don't fit and nasty hacks, such as credential switching or lock dance interleaving inode mutex and cgroup_mutex with object serial number comparison thrown in to decide whether the operation is actually necessary, needed to be employed. After conversion to kernfs, internal object lifetime and locking rules are mostly isolated from vfs interactions allowing shedding of several nasty hacks and overall simplification. This will also allow implmentation of operations which may affect multiple cgroups which weren't possible before as it would have required nesting i_mutexes. - Various simplifications including dropping of module support, easier cgroup name/path handling, simplified cgroup file type handling and task_cg_lists optimization. - Prepatory changes for the planned unified hierarchy, which is still a patchset away from being actually operational. The dummy hierarchy is updated to serve as the default unified hierarchy. Controllers which aren't claimed by other hierarchies are associated with it, which BTW was what the dummy hierarchy was for anyway. - Various fixes from Li and others. This pull request includes some patches to add missing slab.h to various subsystems. This was triggered xattr.h include removal from cgroup.h. cgroup.h indirectly got included a lot of files which brought in xattr.h which brought in slab.h. There are several merge commits - one to pull in kernfs updates necessary for converting cgroup (already in upstream through driver-core), others for interfering changes in the fixes branch" * 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (74 commits) cgroup: remove useless argument from cgroup_exit() cgroup: fix spurious lockdep warning in cgroup_exit() cgroup: Use RCU_INIT_POINTER(x, NULL) in cgroup.c cgroup: break kernfs active_ref protection in cgroup directory operations cgroup: fix cgroup_taskset walking order cgroup: implement CFTYPE_ONLY_ON_DFL cgroup: make cgrp_dfl_root mountable cgroup: drop const from @buffer of cftype->write_string() cgroup: rename cgroup_dummy_root and related names cgroup: move ->subsys_mask from cgroupfs_root to cgroup cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding cgroup: remove NULL checks from [pr_cont_]cgroup_{name|path}() cgroup: use cgroup_setup_root() to initialize cgroup_dummy_root cgroup: reorganize cgroup bootstrapping cgroup: relocate setting of CGRP_DEAD cpuset: use rcu_read_lock() to protect task_cs() cgroup_freezer: document freezer_fork() subtleties cgroup: update cgroup_transfer_tasks() to either succeed or fail cgroup: drop task_lock() protection around task->cgroups cgroup: update how a newly forked task gets associated with css_set ...
2014-03-08kernfs: cache atomic_write_len in kernfs_open_fileTejun Heo1-31/+32
While implementing atomic_write_len, 4d3773c4bb41 ("kernfs: implement kernfs_ops->atomic_write_len") moved data copy from userland inside kernfs_get_active() and kernfs_open_file->mutex so that kernfs_ops->atomic_write_len can be accessed before copying buffer from userland; unfortunately, this could lead to locking order inversion involving mmap_sem if copy_from_user() takes a page fault. ====================================================== [ INFO: possible circular locking dependency detected ] 3.14.0-rc4-next-20140228-sasha-00011-g4077c67-dirty #26 Tainted: G W ------------------------------------------------------- trinity-c236/10658 is trying to acquire lock: (&of->mutex#2){+.+.+.}, at: [<fs/kernfs/file.c:487>] kernfs_fop_mmap+0x54/0x120 but task is already holding lock: (&mm->mmap_sem){++++++}, at: [<mm/util.c:397>] vm_mmap_pgoff+0x6e/0xe0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++++}: [<kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131>] validate_chain+0x6c5/0x7b0 [<kernel/locking/lockdep.c:3182>] __lock_acquire+0x4cd/0x5a0 [<arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602>] lock_acquire+0x182/0x1d0 [<mm/memory.c:4188>] might_fault+0x7e/0xb0 [<arch/x86/include/asm/uaccess.h:713 fs/kernfs/file.c:291>] kernfs_fop_write+0xd8/0x190 [<fs/read_write.c:473>] vfs_write+0xe3/0x1d0 [<fs/read_write.c:523 fs/read_write.c:515>] SyS_write+0x5d/0xa0 [<arch/x86/kernel/entry_64.S:749>] tracesys+0xdd/0xe2 -> #0 (&of->mutex#2){+.+.+.}: [<kernel/locking/lockdep.c:1840>] check_prev_add+0x13f/0x560 [<kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131>] validate_chain+0x6c5/0x7b0 [<kernel/locking/lockdep.c:3182>] __lock_acquire+0x4cd/0x5a0 [<arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602>] lock_acquire+0x182/0x1d0 [<kernel/locking/mutex.c:470 kernel/locking/mutex.c:571>] mutex_lock_nested+0x6a/0x510 [<fs/kernfs/file.c:487>] kernfs_fop_mmap+0x54/0x120 [<mm/mmap.c:1573>] mmap_region+0x310/0x5c0 [<mm/mmap.c:1365>] do_mmap_pgoff+0x385/0x430 [<mm/util.c:399>] vm_mmap_pgoff+0x8f/0xe0 [<mm/mmap.c:1416 mm/mmap.c:1374>] SyS_mmap_pgoff+0x1b0/0x210 [<arch/x86/kernel/sys_x86_64.c:72>] SyS_mmap+0x1d/0x20 [<arch/x86/kernel/entry_64.S:749>] tracesys+0xdd/0xe2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(&of->mutex#2); lock(&mm->mmap_sem); lock(&of->mutex#2); *** DEADLOCK *** 1 lock held by trinity-c236/10658: #0: (&mm->mmap_sem){++++++}, at: [<mm/util.c:397>] vm_mmap_pgoff+0x6e/0xe0 stack backtrace: CPU: 2 PID: 10658 Comm: trinity-c236 Tainted: G W 3.14.0-rc4-next-20140228-sasha-00011-g4077c67-dirty #26 0000000000000000 ffff88011911fa48 ffffffff8438e945 0000000000000000 0000000000000000 ffff88011911fa98 ffffffff811a0109 ffff88011911fab8 ffff88011911fab8 ffff88011911fa98 ffff880119128cc0 ffff880119128cf8 Call Trace: [<lib/dump_stack.c:52>] dump_stack+0x52/0x7f [<kernel/locking/lockdep.c:1213>] print_circular_bug+0x129/0x160 [<kernel/locking/lockdep.c:1840>] check_prev_add+0x13f/0x560 [<include/linux/spinlock.h:343 mm/slub.c:1933>] ? deactivate_slab+0x511/0x550 [<kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131>] validate_chain+0x6c5/0x7b0 [<kernel/locking/lockdep.c:3182>] __lock_acquire+0x4cd/0x5a0 [<mm/mmap.c:1552>] ? mmap_region+0x24a/0x5c0 [<arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602>] lock_acquire+0x182/0x1d0 [<fs/kernfs/file.c:487>] ? kernfs_fop_mmap+0x54/0x120 [<kernel/locking/mutex.c:470 kernel/locking/mutex.c:571>] mutex_lock_nested+0x6a/0x510 [<fs/kernfs/file.c:487>] ? kernfs_fop_mmap+0x54/0x120 [<kernel/sched/core.c:2477>] ? get_parent_ip+0x11/0x50 [<fs/kernfs/file.c:487>] ? kernfs_fop_mmap+0x54/0x120 [<fs/kernfs/file.c:487>] kernfs_fop_mmap+0x54/0x120 [<mm/mmap.c:1573>] mmap_region+0x310/0x5c0 [<mm/mmap.c:1365>] do_mmap_pgoff+0x385/0x430 [<mm/util.c:397>] ? vm_mmap_pgoff+0x6e/0xe0 [<mm/util.c:399>] vm_mmap_pgoff+0x8f/0xe0 [<kernel/rcu/update.c:97>] ? __rcu_read_unlock+0x44/0xb0 [<fs/file.c:641>] ? dup_fd+0x3c0/0x3c0 [<mm/mmap.c:1416 mm/mmap.c:1374>] SyS_mmap_pgoff+0x1b0/0x210 [<arch/x86/kernel/sys_x86_64.c:72>] SyS_mmap+0x1d/0x20 [<arch/x86/kernel/entry_64.S:749>] tracesys+0xdd/0xe2 Fix it by caching atomic_write_len in kernfs_open_file during open so that it can be determined without accessing kernfs_ops in kernfs_fop_write(). This restores the structure of kernfs_fop_write() before 4d3773c4bb41 with updated @len determination logic. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> References: http://lkml.kernel.org/g/53113485.2090407@oracle.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-08kernfs: fix off by one error.Richard Cochran1-1/+1
The hash values 0 and 1 are reserved for magic directory entries, but the code only prevents names hashing to 0. This patch fixes the test to also prevent hash value 1. Signed-off-by: Richard Cochran <richardcochran@gmail.com> Cc: <stable@vger.kernel.org> Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-02Merge 3.14-rc5 into driver-core-nextGreg Kroah-Hartman1-1/+7
We want the fixes in here.
2014-02-25sysfs: fix namespace refcnt leakLi Zefan1-1/+7
As mount() and kill_sb() is not a one-to-one match, we shoudn't get ns refcnt unconditionally in sysfs_mount(), and instead we should get the refcnt only when kernfs_mount() allocated a new superblock. v2: - Changed the name of the new argument, suggested by Tejun. - Made the argument optional, suggested by Tejun. v3: - Make the new argument as second-to-last arg, suggested by Tejun. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> --- fs/kernfs/mount.c | 8 +++++++- fs/sysfs/mount.c | 5 +++-- include/linux/kernfs.h | 9 +++++---- 3 files changed, 15 insertions(+), 7 deletions(-) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-14kernfs: fix kernfs_node_from_dentry()Li Zefan3-2/+3
Currently kernfs_node_from_dentry() returns NULL for root dentry, because root_dentry->d_op == NULL. Due to this bug cgroupstats_build() returns -EINVAL for root cgroup. # mount -t cgroup -o cpuacct /cgroup # Documentation/accounting/getdelays -C /cgroup fatal reply error, errno -22 With this fix: # Documentation/accounting/getdelays -C /cgroup sleeping 305, blocked 0, running 1, stopped 0, uninterruptible 1 Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-12cgroup: remove cgroup->nameTejun Heo1-0/+1
cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-10kernfs: fix hash calculation in kernfs_rename_ns()Tejun Heo1-1/+1
3eef34ad7dc3 ("kernfs: implement kernfs_get_parent(), kernfs_name/path() and friends") restructured kernfs_rename_ns() such that new name assignment happens under kernfs_rename_lock; unfortunately, it mistakenly passed NULL to kernfs_name_hash() to calculate the new hash if the name hasn't changed, which can lead to oops. Fix it by using kn->name and kn->ns when calculating the new hash. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: add CONFIG_KERNFSTejun Heo1-0/+7
As sysfs was kernfs's only user, kernfs has been piggybacking on CONFIG_SYSFS; however, kernfs is scheduled to grow a new user very soon. Introduce a separate config option CONFIG_KERNFS which is to be selected by kernfs users. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: implement kernfs_get_parent(), kernfs_name/path() and friendsTejun Heo1-10/+165
kernfs_node->parent and ->name are currently marked as "published" indicating that kernfs users may access them directly; however, those fields may get updated by kernfs_rename[_ns]() and unrestricted access may lead to erroneous values or oops. Protect ->parent and ->name updates with a irq-safe spinlock kernfs_rename_lock and implement the following accessors for these fields. * kernfs_name() - format the node's name into the specified buffer * kernfs_path() - format the node's path into the specified buffer * pr_cont_kernfs_name() - pr_cont a node's name (doesn't need buffer) * pr_cont_kernfs_path() - pr_cont a node's path (doesn't need buffer) * kernfs_get_parent() - pin and return a node's parent All can be called under any context. The recursive sysfs_pathname() in fs/sysfs/dir.c is replaced with kernfs_path() and sysfs_rename_dir_ns() is updated to use kernfs_get_parent() instead of dereferencing parent directly. v2: Dummy definition of kernfs_path() for !CONFIG_KERNFS was missing static inline making it cause a lot of build warnings. Add it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: implement kernfs_node_from_dentry(), kernfs_root_from_sb() and ↵Tejun Heo2-0/+32
kernfs_rename() Implement helpers to determine node from dentry and root from super_block. Also add a kernfs_rename_ns() wrapper which assumes NULL namespace. These generally make sense and will be used by cgroup. v2: Some dummy implementations for !CONFIG_SYSFS was missing. Fixed. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: implement kernfs_ops->atomic_write_lenTejun Heo1-18/+31
A write to a kernfs_node is buffered through a kernel buffer. Writes <= PAGE_SIZE are performed atomically, while larger ones are executed in PAGE_SIZE chunks. While this is enough for sysfs, cgroup which is scheduled to be converted to use kernfs needs a bit more control over it. This patch adds kernfs_ops->atomic_write_len. If not set (zero), the behavior stays the same. If set, writes upto the size are executed atomically and larger writes are rejected with -E2BIG. A different implementation strategy would be allowing configuring chunking size while making the original write size available to the write method; however, such strategy, while being more complicated, doesn't really buy anything. If the write implementation has to handle chunking, the specific chunk size shouldn't matter all that much. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: allow nodes to be created in the deactivated stateTejun Heo1-7/+64
Currently, kernfs_nodes are made visible to userland on creation, which makes it difficult for kernfs users to atomically succeed or fail creation of multiple nodes. In addition, if something fails after creating some nodes, the created nodes might already be in use and their active refs need to be drained for removal, which has the potential to introduce tricky reverse locking dependency on active_ref depending on how the error path is synchronized. This patch introduces per-root flag KERNFS_ROOT_CREATE_DEACTIVATED. If set, all nodes under the root are created in the deactivated state and stay invisible to userland until explicitly enabled by the new kernfs_activate() API. Also, nodes which have never been activated are guaranteed to bypass draining on removal thus allowing error paths to not worry about lockding dependency on active_ref draining. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: add missing kernfs_active() checks in directory operationsTejun Heo1-5/+6
kernfs_iop_lookup(), kernfs_dir_pos() and kernfs_dir_next_pos() were missing kernfs_active() tests before using the found kernfs_node. As deactivated state is currently visible only while a node is being removed, this doesn't pose an actual problem. e.g. lookup succeeding on a deactivated node doesn't harm anything as the eventual file operations are gonna fail and those failures are indistinguishible from the cases in which the lookups had happened before the node was deactivated. However, we're gonna allow new nodes to be created deactivated and then activated explicitly by the kernfs user when it sees fit. This is to support atomically making multiple nodes visible to userland and thus those nodes must not be visible to userland before activated. Let's plug the lookup and readdir holes so that deactivated nodes are invisible to userland. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: implement kernfs_syscall_ops->remount_fs() and ->show_options()Tejun Heo1-0/+23
Add two super_block related syscall callbacks ->remount_fs() and ->show_options() to kernfs_syscall_ops. These simply forward the matching super_operations. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: rename kernfs_dir_ops to kernfs_syscall_opsTejun Heo1-12/+13
We're gonna need non-dir syscall callbacks, which will make dir_ops a misnomer. Let's rename kernfs_dir_ops to kernfs_syscall_ops. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: invoke dir_ops while holding active ref of the target nodeTejun Heo1-3/+30
kernfs_dir_ops are currently being invoked without any active reference, which makes it tricky for the invoked operations to determine whether the objects associated those nodes are safe to access and will remain that way for the duration of such operations. kernfs already has active_ref mechanism to deal with this which makes the removal of a given node the synchronization point for gating the file operations. There's no reason for dir_ops to be any different. Update the dir_ops handling so that active_ref is held while the dir_ops are executing. This guarantees that while a dir_ops is executing the target nodes stay alive. As kernfs_dir_ops doesn't have any in-kernel user at this point, this doesn't affect anybody. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappersTejun Heo1-1/+137
Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref the task is holding, removes the self node, and restores active ref to the dead node so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. Note that manipulation of active ref is implemented in separate public functions - kernfs_[un]break_active_protection(). kernfs_remove_self() is the only user at the moment but this will be used to cater to more complex cases. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: kernfs_[un]break_active_protection() separated out from kernfs_remove_self() and exposed as public API. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: remove KERNFS_REMOVEDTejun Heo2-32/+37
KERNFS_REMOVED is used to mark half-initialized and dying nodes so that they don't show up in lookups and deny adding new nodes under or renaming it; however, its role overlaps that of deactivation. It's necessary to deny addition of new children while removal is in progress; however, this role considerably intersects with deactivation - KERNFS_REMOVED prevents new children while deactivation prevents new file operations. There's no reason to have them separate making things more complex than necessary. This patch removes KERNFS_REMOVED. * Instead of KERNFS_REMOVED, each node now starts its life deactivated. This means that we now use both atomic_add() and atomic_sub() on KN_DEACTIVATED_BIAS, which is INT_MIN. The compiler generates an overflow warnings when negating INT_MIN as the negation can't be represented as a positive number. Nothing is actually broken but let's bump BIAS by one to avoid the warnings for archs which negates the subtrahend.. * A new helper kernfs_active() which tests whether kn->active >= 0 is added for convenience and lockdep annotation. All KERNFS_REMOVED tests are replaced with negated kernfs_active() tests. * __kernfs_remove() is updated to deactivate, but not drain, all nodes in the subtree instead of setting KERNFS_REMOVED. This removes deactivation from kernfs_deactivate(), which is now renamed to kernfs_drain(). * Sanity check on KERNFS_REMOVED in kernfs_put() is replaced with checks on the active ref. * Some comment style updates in the affected area. v2: Reordered before removal path restructuring. kernfs_active() dropped and kernfs_get/put_active() used instead. RB_EMPTY_NODE() used in the lookup paths. v3: Reverted most of v2 except for creating a new node with KN_DEACTIVATED_BIAS. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep()Tejun Heo1-7/+13
There currently are two mechanisms gating active ref lockdep annotations - KERNFS_LOCKDEP flag and KERNFS_ACTIVE_REF type mask. The former disables lockdep annotations in kernfs_get/put_active() while the latter disables all of kernfs_deactivate(). While KERNFS_ACTIVE_REF also behaves as an optimization to skip the deactivation step for non-file nodes, the benefit is marginal and it needlessly diverges code paths. Let's drop KERNFS_ACTIVE_REF. While at it, add a test helper kernfs_lockdep() to test KERNFS_LOCKDEP flag so that it's more convenient and the related code can be compiled out when not enabled. v2: Refreshed on top of ("kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP flag"). As the earlier patch already added KERNFS_LOCKDEP tests to kernfs_deactivate(), those additions are dropped from this patch and the existing ones are simply converted to kernfs_lockdep(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: remove kernfs_addrm_cxtTejun Heo4-104/+28
kernfs_addrm_cxt and the accompanying kernfs_addrm_start/finish() were added because there were operations which should be performed outside kernfs_mutex after adding and removing kernfs_nodes. The necessary operations were recorded in kernfs_addrm_cxt and performed by kernfs_addrm_finish(); however, after the recent changes which relocated deactivation and unmapping so that they're performed directly during removal, the only operation kernfs_addrm_finish() performs is kernfs_put(), which can be moved inside the removal path too. This patch moves the kernfs_put() of the base ref to __kernfs_remove() and remove kernfs_addrm_cxt and kernfs_addrm_start/finish(). * kernfs_add_one() is updated to grab and release kernfs_mutex itself. sysfs_addrm_start/finish() invocations around it are removed from all users. * __kernfs_remove() puts an unlinked node directly instead of chaining it to kernfs_addrm_cxt. Its callers are updated to grab and release kernfs_mutex instead of calling kernfs_addrm_start/finish() around it. v2: Rebased on top of "kernfs: associate a new kernfs_node with its parent on creation" which dropped @parent from kernfs_add_one(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: invoke kernfs_unmap_bin_file() directly from kernfs_deactivate()Tejun Heo1-4/+6
kernfs_unmap_bin_file() is supposed to unmap all memory mappings of the target file before kernfs_remove() finishes; however, it currently is being called from kernfs_addrm_finish() and has the same race problem as the original implementation of deactivation when there are multiple removers - only the remover which snatches the node to its addrm_cxt->removed list is guaranteed to wait for its completion before returning. It can be easily fixed by moving kernfs_unmap_bin_file() invocation from kernfs_addrm_finish() to kernfs_deactivated(). The function may be called multiple times but that shouldn't do any harm. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: restructure removal path to fix possible premature returnTejun Heo1-61/+68
The recursive nature of kernfs_remove() means that, even if kernfs_remove() is not allowed to be called multiple times on the same node, there may be race conditions between removal of parent and its descendants. While we can claim that kernfs_remove() shouldn't be called on one of the descendants while the removal of an ancestor is in progress, such rule is unnecessarily restrictive and very difficult to enforce. It's better to simply allow invoking kernfs_remove() as the caller sees fit as long as the caller ensures that the node is accessible. The current behavior in such situations is broken. Whoever enters removal path first takes the node off the hierarchy and then deactivates. Following removers either return as soon as it notices that it's not the first one or can't even find the target node as it has already been removed from the hierarchy. In both cases, the following removers may finish prematurely while the nodes which should be removed and drained are still being processed by the first one. This patch restructures so that multiple removers, whether through recursion or direction invocation, always follow the following rules. * When there are multiple concurrent removers, only one puts the base ref. * Regardless of which one puts the base ref, all removers are blocked until the target node is fully deactivated and removed. To achieve the above, removal path now first marks all descendants including self REMOVED and then deactivates and unlinks leftmost descendant one-by-one. kernfs_deactivate() is called directly from __kernfs_removal() and drops and regrabs kernfs_mutex for each descendant to drain active refs. As this means that multiple removers can enter kernfs_deactivate() for the same node, the function is updated so that it can handle multiple deactivators of the same node - only one actually deactivates but all wait till drain completion. The restructured removal path guarantees that a removed node gets unlinked only after the node is deactivated and drained. Combined with proper multiple deactivator handling, this guarantees that any invocation of kernfs_remove() returns only after the node itself and all its descendants are deactivated, drained and removed. v2: Draining separated into a separate loop (used to be in the same loop as unlink) and done from __kernfs_deactivate(). This is to allow exposing deactivation as a separate interface later. Root node removal was broken in v1 patch. Fixed. v3: Revert most of v2 except for root node removal fix and simplification of KERNFS_REMOVED setting loop. v4: Refreshed on top of ("kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP flag"). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: replace kernfs_node->u.completion with kernfs_root->deactivate_waitqTejun Heo1-18/+13
kernfs_node->u.completion is used to notify deactivation completion from kernfs_put_active() to kernfs_deactivate(). We now allow multiple racing removals of the same node and the current removal scheme is no longer correct - kernfs_remove() invocation may return before the node is properly deactivated if it races against another removal. The removal path will be restructured to address the issue. To help such restructure which requires supporting multiple waiters, this patch replaces kernfs_node->u.completion with kernfs_root->deactivate_waitq. This makes deactivation event notifications share a per-root waitqueue_head; however, the wait path is quite cold and this will also allow shaving one pointer off kernfs_node. v2: Refreshed on top of ("kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP flag"). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP flagTejun Heo1-4/+8
kernfs_deactivate() forgot to check whether KERNFS_LOCKDEP is set before performing lockdep annotations and ends up feeding uninitialized lockdep_map to lockdep triggering warning like the following on USB stick hotunplug. usb 1-2: USB disconnect, device number 2 INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 1 PID: 62 Comm: khubd Not tainted 3.13.0-work+ #82 Hardware name: empty empty/S3992, BIOS 080011 10/26/2007 ffff880065ca7f60 ffff88013a4ffa08 ffffffff81cfb6bd 0000000000000002 ffff88013a4ffac8 ffffffff810f8530 ffff88013a4fc710 0000000000000002 ffff880100000000 ffffffff82a3db50 0000000000000001 ffff88013a4fc710 Call Trace: [<ffffffff81cfb6bd>] dump_stack+0x4e/0x7a [<ffffffff810f8530>] __lock_acquire+0x1910/0x1e70 [<ffffffff810f931a>] lock_acquire+0x9a/0x1d0 [<ffffffff8127c75e>] kernfs_deactivate+0xee/0x130 [<ffffffff8127d4c8>] kernfs_addrm_finish+0x38/0x60 [<ffffffff8127d701>] kernfs_remove_by_name_ns+0x51/0xa0 [<ffffffff8127b4f1>] remove_files.isra.1+0x41/0x80 [<ffffffff8127b7e7>] sysfs_remove_group+0x47/0xa0 [<ffffffff8127b873>] sysfs_remove_groups+0x33/0x50 [<ffffffff8177d66d>] device_remove_attrs+0x4d/0x80 [<ffffffff8177e25e>] device_del+0x12e/0x1d0 [<ffffffff819722c2>] usb_disconnect+0x122/0x1a0 [<ffffffff819749b5>] hub_thread+0x3c5/0x1290 [<ffffffff810c6a6d>] kthread+0xed/0x110 [<ffffffff81d0a56c>] ret_from_fork+0x7c/0xb0 Fix it by making kernfs_deactivate() perform lockdep annotations only if KERNFS_LOCKDEP is set. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fabio Estevam <festevam@gmail.com> Reported-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-05kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP flagTejun Heo1-4/+8
kernfs_deactivate() forgot to check whether KERNFS_LOCKDEP is set before performing lockdep annotations and ends up feeding uninitialized lockdep_map to lockdep triggering warning like the following on USB stick hotunplug. usb 1-2: USB disconnect, device number 2 INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 1 PID: 62 Comm: khubd Not tainted 3.13.0-work+ #82 Hardware name: empty empty/S3992, BIOS 080011 10/26/2007 ffff880065ca7f60 ffff88013a4ffa08 ffffffff81cfb6bd 0000000000000002 ffff88013a4ffac8 ffffffff810f8530 ffff88013a4fc710 0000000000000002 ffff880100000000 ffffffff82a3db50 0000000000000001 ffff88013a4fc710 Call Trace: [<ffffffff81cfb6bd>] dump_stack+0x4e/0x7a [<ffffffff810f8530>] __lock_acquire+0x1910/0x1e70 [<ffffffff810f931a>] lock_acquire+0x9a/0x1d0 [<ffffffff8127c75e>] kernfs_deactivate+0xee/0x130 [<ffffffff8127d4c8>] kernfs_addrm_finish+0x38/0x60 [<ffffffff8127d701>] kernfs_remove_by_name_ns+0x51/0xa0 [<ffffffff8127b4f1>] remove_files.isra.1+0x41/0x80 [<ffffffff8127b7e7>] sysfs_remove_group+0x47/0xa0 [<ffffffff8127b873>] sysfs_remove_groups+0x33/0x50 [<ffffffff8177d66d>] device_remove_attrs+0x4d/0x80 [<ffffffff8177e25e>] device_del+0x12e/0x1d0 [<ffffffff819722c2>] usb_disconnect+0x122/0x1a0 [<ffffffff819749b5>] hub_thread+0x3c5/0x1290 [<ffffffff810c6a6d>] kthread+0xed/0x110 [<ffffffff81d0a56c>] ret_from_fork+0x7c/0xb0 Fix it by making kernfs_deactivate() perform lockdep annotations only if KERNFS_LOCKDEP is set. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fabio Estevam <festevam@gmail.com> Reported-by: Alan Stern <stern@rowland.harvard.edu> Reported-by: Jiri Kosina <jkosina@suse.cz> Reported-by: Dave Jones <davej@redhat.com> Tested-by: Fabio Estevam <fabio.estevam@freescale.com> Tested-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-17kernfs: associate a new kernfs_node with its parent on creationTejun Heo4-24/+34
Once created, a kernfs_node is always destroyed by kernfs_put(). Since ba7443bc656e ("sysfs, kernfs: implement kernfs_create/destroy_root()"), kernfs_put() depends on kernfs_root() to locate the ino_ida. kernfs_root() in turn depends on kernfs_node->parent being set for !dir nodes. This means that kernfs_put() of a !dir node requires its ->parent to be initialized. This leads to oops when a newly created !dir node is destroyed without going through kernfs_add_one() or after failing kernfs_add_one() before ->parent is set. kernfs_root() invoked from kernfs_put() will try to dereference NULL parent. Fix it by moving parent association to kernfs_new_node() from kernfs_add_one(). kernfs_new_node() now takes @parent instead of @root and determines the root from the parent and also sets the new node's parent properly. @parent parameter is removed from kernfs_add_one(). As there's no parent when creating the root node, __kernfs_new_node() which takes @root as before and doesn't set the parent is used in that case. This ensures that a kernfs_node in any stage in its life has its parent associated and thus can be put. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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