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2013-12-07sysfs: give different locking key to regular and bin filesTejun Heo
027a485d12e0 ("sysfs: use a separate locking class for open files depending on mmap") assigned different lockdep key to sysfs_open_file->mutex depending on whether the file implements mmap or not in an attempt to avoid spurious lockdep warning caused by merging of regular and bin file paths. While this restored some of the original behavior of using different locks (at least lockdep is concerned) for the different clases of files. The restoration wasn't full because now the lockdep key assignment depends on whether the file has mmap or not instead of whether it's a regular file or not. This means that bin files which don't implement mmap will get assigned the same lockdep class as regular files. This is problematic because file_operations for bin files still implements the mmap file operation and checking whether the sysfs file actually implements mmap happens in the file operation after grabbing @sysfs_open_file->mutex. We still end up adding locking dependency from mmap locking to sysfs_open_file->mutex to the regular file mutex which triggers spurious circular locking warning. Fix it by restoring the original behavior fully by differentiating lockdep key by whether the file is regular or bin, instead of the existence of mmap. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/g/20131203184324.GA11320@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-27Revert "sysfs: handle duplicate removal attempts in sysfs_remove_group()"Greg Kroah-Hartman
This reverts commit 54d71145a4548330313ca664a4a009772fe8b7dd. The root cause of these "inverted" sysfs removals have now been found, so there is no need for this patch. Keep this functionality around so that this type of error doesn't show up in driver code again. Cc: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23sysfs: use a separate locking class for open files depending on mmapTejun Heo
The following two commits implemented mmap support in the regular file path and merged bin file support into the regular path. 73d9714627ad ("sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.c") 3124eb1679b2 ("sysfs: merge regular and bin file handling") After the merge, the following commands trigger a spurious lockdep warning. "test-mmap-read" simply mmaps the file and dumps the content. $ cat /sys/block/sda/trace/act_mask $ test-mmap-read /sys/devices/pci0000\:00/0000\:00\:03.0/resource0 4096 ====================================================== [ INFO: possible circular locking dependency detected ] 3.12.0-work+ #378 Not tainted ------------------------------------------------------- test-mmap-read/567 is trying to acquire lock: (&of->mutex){+.+.+.}, at: [<ffffffff8120a8df>] sysfs_bin_mmap+0x4f/0x120 but task is already holding lock: (&mm->mmap_sem){++++++}, at: [<ffffffff8114b399>] vm_mmap_pgoff+0x49/0xa0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&mm->mmap_sem){++++++}: ... -> #2 (sr_mutex){+.+.+.}: ... -> #1 (&bdev->bd_mutex){+.+.+.}: ... -> #0 (&of->mutex){+.+.+.}: ... other info that might help us debug this: Chain exists of: &of->mutex --> sr_mutex --> &mm->mmap_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(sr_mutex); lock(&mm->mmap_sem); lock(&of->mutex); *** DEADLOCK *** 1 lock held by test-mmap-read/567: #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8114b399>] vm_mmap_pgoff+0x49/0xa0 stack backtrace: CPU: 3 PID: 567 Comm: test-mmap-read Not tainted 3.12.0-work+ #378 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 ffffffff81ed41a0 ffff880009441bc8 ffffffff81611ad2 ffffffff81eccb80 ffff880009441c08 ffffffff8160f215 ffff880009441c60 ffff880009c75208 0000000000000000 ffff880009c751e0 ffff880009c75208 ffff880009c74ac0 Call Trace: [<ffffffff81611ad2>] dump_stack+0x4e/0x7a [<ffffffff8160f215>] print_circular_bug+0x2b0/0x2bf [<ffffffff8109ca0a>] __lock_acquire+0x1a3a/0x1e60 [<ffffffff8109d6ba>] lock_acquire+0x9a/0x1d0 [<ffffffff81615547>] mutex_lock_nested+0x67/0x3f0 [<ffffffff8120a8df>] sysfs_bin_mmap+0x4f/0x120 [<ffffffff8115d363>] mmap_region+0x3b3/0x5b0 [<ffffffff8115d8ae>] do_mmap_pgoff+0x34e/0x3d0 [<ffffffff8114b3ba>] vm_mmap_pgoff+0x6a/0xa0 [<ffffffff8115be3e>] SyS_mmap_pgoff+0xbe/0x250 [<ffffffff81008282>] SyS_mmap+0x22/0x30 [<ffffffff8161a4d2>] system_call_fastpath+0x16/0x1b This happens because one file nests sr_mutex, which nests mm->mmap_sem under it, under of->mutex while mmap implementation naturally nests of->mutex under mm->mmap_sem. The warning is false positive as of->mutex is per open-file and the two paths belong to two different files. This warning didn't trigger before regular and bin file supports were merged because only bin file supported mmap and the other side of locking happened only on regular files which used equivalent but separate locking. It'd be best if we give separate locking classes per file but we can't easily do that. Let's differentiate on ->mmap() for now. Later we'll add explicit file operations struct and can add per-ops lockdep key there. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23sysfs: handle duplicate removal attempts in sysfs_remove_group()Mika Westerberg
Commit bcdde7e221a8 (sysfs: make __sysfs_remove_dir() recursive) changed the behavior so that directory removals will be done recursively. This means that the sysfs group might already be removed if its parent directory has been removed. The current code outputs warnings similar to following log snippet when it detects that there is no group for the given kobject: WARNING: CPU: 0 PID: 4 at fs/sysfs/group.c:214 sysfs_remove_group+0xc6/0xd0() sysfs group ffffffff81c6f1e0 not found for kobject 'host7' Modules linked in: CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 3.12.0+ #13 Hardware name: /D33217CK, BIOS GKPPT10H.86A.0042.2013.0422.1439 04/22/2013 Workqueue: kacpi_hotplug acpi_hotplug_work_fn 0000000000000009 ffff8801002459b0 ffffffff817daab1 ffff8801002459f8 ffff8801002459e8 ffffffff810436b8 0000000000000000 ffffffff81c6f1e0 ffff88006d440358 ffff88006d440188 ffff88006e8b4c28 ffff880100245a48 Call Trace: [<ffffffff817daab1>] dump_stack+0x45/0x56 [<ffffffff810436b8>] warn_slowpath_common+0x78/0xa0 [<ffffffff81043727>] warn_slowpath_fmt+0x47/0x50 [<ffffffff811ad319>] ? sysfs_get_dirent_ns+0x49/0x70 [<ffffffff811ae526>] sysfs_remove_group+0xc6/0xd0 [<ffffffff81432f7e>] dpm_sysfs_remove+0x3e/0x50 [<ffffffff8142a0d0>] device_del+0x40/0x1b0 [<ffffffff8142a24d>] device_unregister+0xd/0x20 [<ffffffff8144131a>] scsi_remove_host+0xba/0x110 [<ffffffff8145f526>] ata_host_detach+0xc6/0x100 [<ffffffff8145f578>] ata_pci_remove_one+0x18/0x20 [<ffffffff812e8f48>] pci_device_remove+0x28/0x60 [<ffffffff8142d854>] __device_release_driver+0x64/0xd0 [<ffffffff8142d8de>] device_release_driver+0x1e/0x30 [<ffffffff8142d257>] bus_remove_device+0xf7/0x140 [<ffffffff8142a1b1>] device_del+0x121/0x1b0 [<ffffffff812e43d4>] pci_stop_bus_device+0x94/0xa0 [<ffffffff812e437b>] pci_stop_bus_device+0x3b/0xa0 [<ffffffff812e437b>] pci_stop_bus_device+0x3b/0xa0 [<ffffffff812e44dd>] pci_stop_and_remove_bus_device+0xd/0x20 [<ffffffff812fc743>] trim_stale_devices+0x73/0xe0 [<ffffffff812fc78b>] trim_stale_devices+0xbb/0xe0 [<ffffffff812fc78b>] trim_stale_devices+0xbb/0xe0 [<ffffffff812fcb6e>] acpiphp_check_bridge+0x7e/0xd0 [<ffffffff812fd90d>] hotplug_event+0xcd/0x160 [<ffffffff812fd9c5>] hotplug_event_work+0x25/0x60 [<ffffffff81316749>] acpi_hotplug_work_fn+0x17/0x22 [<ffffffff8105cf3a>] process_one_work+0x17a/0x430 [<ffffffff8105db29>] worker_thread+0x119/0x390 [<ffffffff8105da10>] ? manage_workers.isra.25+0x2a0/0x2a0 [<ffffffff81063a5d>] kthread+0xcd/0xf0 [<ffffffff81063990>] ? kthread_create_on_node+0x180/0x180 [<ffffffff817eb33c>] ret_from_fork+0x7c/0xb0 [<ffffffff81063990>] ? kthread_create_on_node+0x180/0x180 On this particular machine I see ~16 of these message during Thunderbolt hot-unplug. Fix this in similar way that was done for sysfs_remove_one() by checking if the parent directory has already been removed and bailing out early. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-07Revert "sysfs: drop kobj_ns_type handling"Linus Torvalds
This reverts commit cb26a311578e67769e92a39a0a63476533cb7e12. It mysteriously causes NetworkManager to not find the wireless device for me. As far as I can tell, Tejun *meant* for this commit to not make any semantic changes, but there clearly are some. So revert it, taking into account some of the calling convention changes that happened in this area in subsequent commits. Cc: Tejun Heo <tj@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-01sysfs: rename sysfs_assoc_lock and explain what it's aboutTejun Heo
sysfs_assoc_lock is an odd piece of locking. In general, whoever owns a kobject is responsible for synchronizing sysfs operations and sysfs proper assumes that, for example, removal won't race with any other operation; however, this doesn't work for symlinking because an entity performing symlink doesn't usually own the target kobject and thus has no control over its removal. sysfs_assoc_lock synchronizes symlink operations against kobj->sd disassociation so that symlink code doesn't end up dereferencing already freed sysfs_dirent by racing with removal of the target kobject. This is quite obscure and the generic name of the lock and lack of comments make it difficult to understand its role. Let's rename it to sysfs_symlink_target_lock and add comments explaining what's going on. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-01sysfs: use generic_file_llseek() for sysfs_file_operationsTejun Heo
13c589d5b0ac6 ("sysfs: use seq_file when reading regular files") converted regular sysfs files to use seq_file. The commit substituted generic_file_llseek() with seq_lseek() for llseek implementation. Before the change, all regular sysfs files were allowed to seek to any position in [0, PAGE_SIZE] as the file size is always PAGE_SIZE and generic_file_llseek() allows any seeking inside the range under file size; however, seq_lseek()'s behavior is different. It traverses the output by repeatedly invoking ->show() until it reaches the target offset or traversal indicates EOF. As seq_files are fully dynamic and may not end at all, it doesn't support seeking from the end (SEEK_END). Apparently, there are userland tools which uses SEEK_END to discover the buffer size to use and the switch to seq_lseek() disturbs them as SEEK_END fails with -EINVAL. The only benefits of using seq_lseek() instead of generic_file_llseek() are * Early failure. If traversing to certain file position should fail, seq_lseek() will report such failures on lseek(2) instead of the following read/write operations. * EOF detection. While SEEK_END is not supported, SEEK_SET/CUR + large offset can be used to detect eof - eof at the time of the seek anyway as the file size may change dynamically. Both aren't necessary for sysfs or prospect kernfs users. Revert to genefic_file_llseek() and preserve the original behavior. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Link: https://lkml.kernel.org/r/20131031114358.GA5551@osiris Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-30sysfs: return correct error code on unimplemented mmap()Vladimir Zapolskiy
Both POSIX.1-2008 and Linux Programmer's Manual have a dedicated return error code for a case, when a file doesn't support mmap(), it's ENODEV. This change replaces overloaded EINVAL with ENODEV in a situation described above for sysfs binary files. Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-29sysfs: separate out dup filename warning into a separate functionTejun Heo
Separate out sysfs_warn_dup() out of sysfs_add_one(). This will help separating out the core sysfs functionalities into kernfs so that it can be used by non-sysfs users too. This doesn't make any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-29sysfs: move sysfs_hash_and_remove() to fs/sysfs/dir.cTejun Heo
Most removal related logic is implemented in fs/sysfs/dir.c. Move sysfs_hash_and_remove() to fs/sysfs/dir.c so that __sysfs_remove() doesn't have to be public. This is pure relocation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-29sysfs: remove unused sysfs_get_dentry() prototypeTejun Heo
sysfs_get_dentry() has been gone for years now. Remove the left-over prototype. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-29sysfs: honor bin_attr.attr.ignore_lockdepTejun Heo
ignore_lockdep is currently honored only for regular files. There's no reason to ignore it for bin files. Update sysfs_ignore_lockdep() so that bin_attr.attr.ignore_lockdep works too. While this doesn't have any in-kernel user, this unifies the behaviors between regular and bin files and will help later changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-29sysfs: merge sysfs_elem_bin_attr into sysfs_elem_attrTejun Heo
3124eb1679 ("sysfs: merge regular and bin file handling") folded bin file handling into regular file handling. Among other things, bin file now shares the same open path including sysfs_open_dirent association using sysfs_dirent->s_attr.open. This is buggy because ->s_bin_attr lives in the same union and doesn't have the field. This bug doesn't trigger because sysfs_elem_bin_attr doesn't have an active field at the conflicting position. It does have a field "buffers" but it isn't used anymore. This patch collapses sysfs_elem_bin_attr into sysfs_elem_attr so that the bin_attr is accessed through ->s_attr.bin_attr which lives with ->s_attr.attr in an anonymous union. The code paths already assume bin_attr contains attr as the first element, so this doesn't add any more assumptions while making it explicit that the two types are handled together. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-25sysfs: fix sysfs_write_file for bin fileMing Lei
Before patch(sysfs: prepare path write for unified regular / bin file handling), when size of bin file is zero, writting still can continue, but this patch changes the behaviour. The worse thing is that firmware loader is broken by this patch, and user space application can't write to firmware bin file any more because both firmware loader and drivers can't know at advance how large the firmware file is and have to set its initialized size as zero. This patch fixes the problem and keeps behaviour of writting to bin as before. Reported-by: Lothar Waßmann <LW@karo-electronics.de> Tested-by: Lothar Waßmann <LW@karo-electronics.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-14sysfs/bin: Fix size handling overflow for bin_attributeBenjamin Herrenschmidt
While looking at the code, I noticed that bin_attribute read() and write() ops copy the inode size into an int for futher comparisons. Some bin_attributes can be fairly large. For example, pci creates some for BARs set to the BAR size and giant BARs are around the corner, so this is going to break something somewhere eventually. Let's use the right type. [adjust for seqfile conversions, only needed for bin_read() - gkh] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-14sysfs: make sysfs_file_ops() follow ignore_lockdep flagTejun Heo
375b611e60 ("sysfs: remove sysfs_buffer->ops") introduced sysfs_file_ops() which determines the associated file operation of a given sysfs_dirent. As file ops access should be protected by an active reference, the new function includes a lockdep assertion on the sysfs_dirent; unfortunately, I forgot to take attr->ignore_lockdep flag into account and the lockdep assertion trips spuriously for files which opt out from active reference lockdep checking. # cat /sys/devices/pci0000:00/0000:00:01.2/usb1/authorized ------------[ cut here ]------------ WARNING: CPU: 1 PID: 540 at /work/os/work/fs/sysfs/file.c:79 sysfs_file_ops+0x4e/0x60() Modules linked in: CPU: 1 PID: 540 Comm: cat Not tainted 3.11.0-work+ #3 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000009 ffff880016205c08 ffffffff81ca0131 0000000000000000 ffff880016205c40 ffffffff81096d0d ffff8800166cb898 ffff8800166f6f60 ffffffff8125a220 ffff880011ab1ec0 ffff88000aff0c78 ffff880016205c50 Call Trace: [<ffffffff81ca0131>] dump_stack+0x4e/0x82 [<ffffffff81096d0d>] warn_slowpath_common+0x7d/0xa0 [<ffffffff81096dea>] warn_slowpath_null+0x1a/0x20 [<ffffffff8125994e>] sysfs_file_ops+0x4e/0x60 [<ffffffff8125a274>] sysfs_open_file+0x54/0x300 [<ffffffff811df612>] do_dentry_open.isra.17+0x182/0x280 [<ffffffff811df820>] finish_open+0x30/0x40 [<ffffffff811f0623>] do_last+0x503/0xd90 [<ffffffff811f0f6b>] path_openat+0xbb/0x6d0 [<ffffffff811f23ba>] do_filp_open+0x3a/0x90 [<ffffffff811e09a9>] do_sys_open+0x129/0x220 [<ffffffff811e0abe>] SyS_open+0x1e/0x20 [<ffffffff81caf3c2>] system_call_fastpath+0x16/0x1b ---[ end trace aa48096b111dafdb ]--- Rename fs/sysfs/dir.c::ignore_lockdep() to sysfs_ignore_lockdep() and move it to fs/sysfs/sysfs.h and make sysfs_file_ops() skip lockdep assertion if sysfs_ignore_lockdep() is true. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: merge regular and bin file handlingTejun Heo
With the previous changes, sysfs regular file code is ready to handle bin files too. This patch makes bin files share the regular file path. * sysfs_create/remove_bin_file() are moved to fs/sysfs/file.c. * sysfs_init_inode() is updated to use the new sysfs_bin_operations instead of bin_fops for bin files. * fs/sysfs/bin.c and the related pieces are removed. This patch shouldn't introduce any behavior difference to bin file accesses. Overall, this unification reduces the amount of duplicate logic, makes behaviors more consistent and paves the road for building simpler and more versatile interface which will allow other subsystems to make use of sysfs for their pseudo filesystems. v2: Stale fs/sysfs/bin.c reference dropped from Documentation/DocBook/filesystems.tmpl. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay@vrfy.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: prepare open path for unified regular / bin file handlingTejun Heo
sysfs bin file handling will be merged into the regular file support. This patch prepares the open path. This patch updates sysfs_open_file() such that it can handle both regular and bin files. This is a preparation and the new bin file path isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.cTejun Heo
sysfs bin file handling will be merged into the regular file support. This patch copies mmap support from bin so that fs/sysfs/file.c can handle mmapping bin files. The code is copied mostly verbatim with the following updates. * ->mmapped and ->vm_ops are added to sysfs_open_file and bin_buffer references are replaced with sysfs_open_file ones. * Symbols are prefixed with sysfs_. * sysfs_unmap_bin_file() grabs sysfs_open_dirent and traverses ->files. Invocation of this function is added to sysfs_addrm_finish(). * sysfs_bin_mmap() is added to sysfs_bin_operations. This is a preparation and the new mmap path isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: add sysfs_bin_read()Tejun Heo
sysfs bin file handling will be merged into the regular file support. This patch prepares the read path. Copy fs/sysfs/bin.c::read() to fs/sysfs/file.c and make it use sysfs_open_file instead of bin_buffer. The function is identical copy except for the use of sysfs_open_file. The new function is added to sysfs_bin_operations. This isn't used yet but will eventually replace fs/sysfs/bin.c. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: prepare path write for unified regular / bin file handlingTejun Heo
sysfs bin file handling will be merged into the regular file support. This patch prepares the write path. bin file write is almost identical to regular file write except that the write length is capped by the inode size and @off is passed to the write method. This patch adds bin file handling to sysfs_write_file() so that it can handle both regular and bin files. A new file_operations struct sysfs_bin_operations is added, which currently only hosts sysfs_write_file() and generic_file_llseek(). This isn't used yet but will eventually replace fs/sysfs/bin.c. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: collapse fs/sysfs/bin.c::fill_read() into read()Tejun Heo
read() is simple enough and fill_read() being in a separate function doesn't add anything. Let's collapse it into read(). This will make merging bin file handling with regular file. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: skip bin_buffer->buffer while readingTejun Heo
After b31ca3f5dfc ("sysfs: fix deadlock"), bin read() first writes data to bb->buffer and bounces it to a transient kernel buffer which is then copied out to userland. The double bouncing doesn't add anything. Let's just use the transient buffer directly. While at it, rename @temp to @buf for clarity. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: use seq_file when reading regular filesTejun Heo
sysfs read path implements its own buffering scheme between userland and kernel callbacks, which essentially is a degenerate duplicate of seq_file. This patch replaces the custom read buffering implementation in sysfs with seq_file. While the amount of code reduction is small, this reduces low level hairiness and enables future development of a new versatile API based on seq_file so that sysfs features can be shared with other subsystems. As write path was already converted to not use sysfs_open_file->page, this patch makes ->page and ->count unused and removes them. Userland behavior remains the same except for some extreme corner cases - e.g. sysfs will now regenerate the content each time a file is read after a non-contiguous seek whereas the original code would keep using the same content. While this is a userland visible behavior change, it is extremely unlikely to be noticeable and brings sysfs behavior closer to that of procfs. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: use transient write bufferTejun Heo
There isn't much to be gained by keeping around kernel buffer while a file is open especially as the read path planned to be converted to use seq_file and won't use the buffer. This patch makes sysfs_write_file() use per-write transient buffer instead of sysfs_open_file->page. This simplifies the write path, enables removing sysfs_open_file->page once read path is updated and will help merging bin file write path which already requires the use of a transient buffer due to a locking order issue. As the function comments of flush_write_buffer() and sysfs_write_buffer() are being updated anyway, reformat them so that they're more conventional. v2: Use min_t() instead of min() in sysfs_write_file() to avoid build warning on arm. Reported by build 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>
2013-10-05sysfs: add sysfs_open_file->sd and ->fileTejun Heo
sysfs will be converted to use seq_file for read path, which will make it difficult to pass around multiple pointers directly. This patch adds sysfs_open_file->sd and ->file so that we can reach all the necessary data structures from sysfs_open_file. flush_write_buffer() is updated to drop @dentry which was used to discover the sysfs_dirent as it's now available through sysfs_open_file->sd. This patch doesn't cause any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: rename sysfs_buffer to sysfs_open_fileTejun Heo
sysfs read path will be converted to use seq_file which will handle buffering making sysfs_buffer a misnomer. Rename sysfs_buffer to sysfs_open_file, and sysfs_open_dirent->buffers to ->files. This path is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: add sysfs_open_file_mutexTejun Heo
Add a separate mutex to protect sysfs_open_dirent->buffers list. This will allow performing sleepable operations while traversing sysfs_buffers, which will be renamed to sysfs_open_file. Note that currently sysfs_open_dirent->buffers list isn't being used for anything and this patch doesn't make any functional difference. It will be used to merge regular and bin file supports. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: remove sysfs_buffer->opsTejun Heo
Currently, sysfs_ops is fetched during sysfs_open_file() and cached in sysfs_buffer->ops to be used while the file is open. This patch removes the caching and makes each operation directly fetch sysfs_ops. This patch doesn't introduce any behavior difference and is to prepare for merging regular and bin file supports. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: remove sysfs_buffer->needs_read_fillTejun Heo
->needs_read_fill is used to implement the following behaviors. 1. Ensure buffer filling on the first read. 2. Force buffer filling after a write. 3. Force buffer filling after a successful poll. However, #2 and #3 don't really work as sysfs doesn't reset file position. While the read buffer would be refilled, the next read would continue from the position after the last read or write, requiring an explicit seek to the start for it to be useful, which makes ->needs_read_fill superflous as read buffer is always refilled if f_pos == 0. Update sysfs_read_file() to test buffer->page for #1 instead and remove ->needs_read_fill. While this changes behavior in extreme corner cases - e.g. re-reading a sysfs file after seeking to non-zero position after a write or poll, it's highly unlikely to lead to actual breakage. This change is to prepare for using seq_file in the read path. While at it, reformat a comment in fill_write_buffer(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: remove unused sysfs_buffer->posTejun Heo
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-03sysfs: introduce [__]sysfs_remove()Tejun Heo
Given a sysfs_dirent, there is no reason to have multiple versions of removal functions. A function which removes the specified sysfs_dirent and its descendants is enough. This patch intorduces [__}sysfs_remove() which replaces all internal variations of removal functions. This will be the only removal function in the planned new sysfs_dirent based interface. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-03sysfs: make __sysfs_remove_dir() recursiveTejun Heo
Currently, sysfs directory removal is inconsistent in that it would remove any files directly under it but wouldn't recurse into directories. Thanks to group subdirectories, this doesn't even match with kobject boundaries. sysfs is in the process of being separated out so that it can be used by multiple subsystems and we want to have a consistent behavior - either removal of a sysfs_dirent should remove every descendant entries or none instead of something inbetween. This patch implements proper recursive removal in __sysfs_remove_dir(). The function now walks its subtree in a post-order walk to remove all descendants. This is a behavior change but kobject / driver layer, which currently is the only consumer, has already been updated to handle duplicate removal attempts, so nothing should be broken after this change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-03kobject: grab an extra reference on kobject->sd to allow duplicate deletesTejun Heo
sysfs currently has a rather weird behavior regarding removals. A directory removal would delete all files directly under it but wouldn't recurse into subdirectories, which, while a bit inconsistent, seems to make sense at the first glance as each directory is supposedly associated with a kobject and each kobject can take care of the directory deletion; however, this doesn't really hold as we have groups which can be directories without a kobject associated with it and require explicit deletions. We're in the process of separating out sysfs from kboject / driver core and want a consistent behavior. A removal should delete either only the specified node or everything under it. I think it is helpful to support recursive atomic removal and later patches will implement it. Such change means that a sysfs_dirent associated with kobject may be deleted before the kobject itself is removed if one of its ancestor gets removed before it. As sysfs_remove_dir() puts the base ref, we may end up with dangling pointer on descendants. This can be solved by holding an extra reference on the sd from kobject. Acquire an extra reference on the associated sysfs_dirent on directory creation and put it after removal. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-03sysfs: remove sysfs_addrm_cxt->parent_sdTejun Heo
sysfs_addrm_start/finish() enclose sysfs_dirent additions and deletions and sysfs_addrm_cxt is used to record information necessary to finish the operations. Currently, sysfs_addrm_start() takes @parent_sd, records it in sysfs_addrm_cxt, and assumes that all operations in the block are performed under that @parent_sd. This assumption has been fine until now but we want to make some operations behave recursively and, while having @parent_sd recorded in sysfs_addrm_cxt doesn't necessarily prevents that, it becomes confusing. This patch removes sysfs_addrm_cxt->parent_sd and makes sysfs_add_one() take an explicit @parent_sd parameter. Note that sysfs_remove_one() doesn't need the extra argument as its parent is always known from the target @sd. While at it, add __acquires/releases() notations to sysfs_addrm_start/finish() respectively. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: @name comes before @nsTejun Heo
Some internal sysfs functions which take explicit namespace argument are weird in that they place the optional @ns in front of @name which is contrary to the established convention. This is confusing and error-prone especially as @ns and @name may be interchanged without causing compilation warning. Swap the positions of @name and @ns in the following internal functions. sysfs_find_dirent() sysfs_rename() sysfs_hash_and_remove() sysfs_name_hash() sysfs_name_compare() create_dir() This patch doesn't introduce any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: clean up sysfs_get_dirent()Tejun Heo
The pre-existing sysfs interfaces which take explicit namespace argument are weird in that they place the optional @ns in front of @name which is contrary to the established convention. For example, we end up forcing vast majority of sysfs_get_dirent() users to do sysfs_get_dirent(parent, NULL, name), which is silly and error-prone especially as @ns and @name may be interchanged without causing compilation warning. This renames sysfs_get_dirent() to sysfs_get_dirent_ns() and swap the positions of @name and @ns, and sysfs_get_dirent() is now a wrapper around sysfs_get_dirent_ns(). This makes confusions a lot less likely. There are other interfaces which take @ns before @name. They'll be updated by following patches. This patch doesn't introduce any functional changes. v2: EXPORT_SYMBOL_GPL() wasn't updated leading to undefined symbol error on module builds. Reported by build test robot. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: drop kobj_ns_type handlingTejun Heo
The way namespace tags are implemented in sysfs is more complicated than necessary. As each tag is a pointer value and required to be non-NULL under a namespace enabled parent, there's no need to record separately what type each tag is or where namespace is enabled. If multiple namespace types are needed, which currently aren't, we can simply compare the tag to a set of allowed tags in the superblock assuming that the tags, being pointers, won't have the same value across multiple types. Also, whether to filter by namespace tag or not can be trivially determined by whether the node has any tagged children or not. This patch rips out kobj_ns_type handling from sysfs. sysfs no longer cares whether specific type of namespace is enabled or not. If a sysfs_dirent has a non-NULL tag, the parent is marked as needing namespace filtering and the value is tested against the allowed set of tags for the superblock (currently only one but increasing this number isn't difficult) and the sysfs_dirent is ignored if it doesn't match. This removes most kobject namespace knowledge from sysfs proper which will enable proper separation and layering of sysfs. The namespace sanity checks in fs/sysfs/dir.c are replaced by the new sanity check in kobject_namespace(). As this is the only place ktype->namespace() is called for sysfs, this doesn't weaken the sanity check significantly. I omitted converting the sanity check in sysfs_do_create_link_sd(). While the check can be shifted to upper layer, mistakes there are well contained and should be easily visible anyway. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: remove ktype->namespace() invocations in symlink codeTejun Heo
There's no reason for sysfs to be calling ktype->namespace(). It is backwards, obfuscates what's going on and unnecessarily tangles two separate layers. There are two places where symlink code calls ktype->namespace(). * sysfs_do_create_link_sd() calls it to find out the namespace tag of the target directory. Unless symlinking races with cross-namespace renaming, this equals @target_sd->s_ns. * sysfs_rename_link() uses it to find out the new namespace to rename to and the new namespace can be different from the existing one. The function is renamed to sysfs_rename_link_ns() with an explicit @ns argument and the ktype->namespace() invocation is shifted to the device layer. While this patch replaces ktype->namespace() invocation with the recorded result in @target_sd, this shouldn't result in any behvior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: remove ktype->namespace() invocations in directory codeTejun Heo
For some unrecognizable reason, namespace information is communicated to sysfs through ktype->namespace() callback when there's *nothing* which needs the use of a callback. The whole sequence of operations is completely synchronous and sysfs operations simply end up calling back into the layer which just invoked it in order to find out the namespace information, which is completely backwards, obfuscates what's going on and unnecessarily tangles two separate layers. This patch doesn't remove ktype->namespace() but shifts its handling to kobject layer. We probably want to get rid of the callback in the long term. This patch adds an explicit param to sysfs_{create|rename|move}_dir() and renames them to sysfs_{create|rename|move}_dir_ns(), respectively. ktype->namespace() invocations are moved to the calling sites of the above functions. A new helper kboject_namespace() is introduced which directly tests kobj_ns_type_operations->type which should give the same result as testing sysfs_fs_type(parent_sd) and returns @kobj's namespace tag as necessary. kobject_namespace() is extern as it will be used from another file in the following patches. This patch should be an equivalent conversion without any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: make attr namespace interface less convolutedTejun Heo
sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26sysfs: drop semicolon from to_sysfs_dirent() definitionTejun Heo
The expansion of to_sysfs_dirent() contains an unncessary trailing semicolon making it impossible to use in the middle of statements. Drop it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-07Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile 2 (of many) from Al Viro: "Mostly Miklos' series this time" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: constify dcache.c inlined helpers where possible fuse: drop dentry on failed revalidate fuse: clean up return in fuse_dentry_revalidate() fuse: use d_materialise_unique() sysfs: use check_submounts_and_drop() nfs: use check_submounts_and_drop() gfs2: use check_submounts_and_drop() afs: use check_submounts_and_drop() vfs: check unlinked ancestors before mount vfs: check submounts and drop atomically vfs: add d_walk() vfs: restructure d_genocide()
2013-09-07Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull namespace changes from Eric Biederman: "This is an assorted mishmash of small cleanups, enhancements and bug fixes. The major theme is user namespace mount restrictions. nsown_capable is killed as it encourages not thinking about details that need to be considered. A very hard to hit pid namespace exiting bug was finally tracked and fixed. A couple of cleanups to the basic namespace infrastructure. Finally there is an enhancement that makes per user namespace capabilities usable as capabilities, and an enhancement that allows the per userns root to nice other processes in the user namespace" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: userns: Kill nsown_capable it makes the wrong thing easy capabilities: allow nice if we are privileged pidns: Don't have unshare(CLONE_NEWPID) imply CLONE_THREAD userns: Allow PR_CAPBSET_DROP in a user namespace. namespaces: Simplify copy_namespaces so it is clear what is going on. pidns: Fix hang in zap_pid_ns_processes by sending a potentially extra wakeup sysfs: Restrict mounting sysfs userns: Better restrictions on when proc and sysfs can be mounted vfs: Don't copy mount bind mounts of /proc/<pid>/ns/mnt between namespaces kernel/nsproxy.c: Improving a snippet of code. proc: Restrict mounting the proc filesystem vfs: Lock in place mounts from more privileged users
2013-09-05sysfs: use check_submounts_and_drop()Miklos Szeredi
Do have_submounts(), shrink_dcache_parent() and d_drop() atomically. check_submounts_and_drop() can deal with negative dentries and non-directories as well. Non-directories can also be mounted on. And just like directories we don't want these to disappear with invalidation. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-08-28sysfs: Restrict mounting sysfsEric W. Biederman
Don't allow mounting sysfs unless the caller has CAP_SYS_ADMIN rights over the net namespace. The principle here is if you create or have capabilities over it you can mount it, otherwise you get to live with what other people have mounted. Instead of testing this with a straight forward ns_capable call, perform this check the long and torturous way with kobject helpers, this keeps direct knowledge of namespaces out of sysfs, and preserves the existing sysfs abstractions. Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-08-26userns: Better restrictions on when proc and sysfs can be mountedEric W. Biederman
Rely on the fact that another flavor of the filesystem is already mounted and do not rely on state in the user namespace. Verify that the mounted filesystem is not covered in any significant way. I would love to verify that the previously mounted filesystem has no mounts on top but there are at least the directories /proc/sys/fs/binfmt_misc and /sys/fs/cgroup/ that exist explicitly for other filesystems to mount on top of. Refactor the test into a function named fs_fully_visible and call that function from the mount routines of proc and sysfs. This makes this test local to the filesystems involved and the results current of when the mounts take place, removing a weird threading of the user namespace, the mount namespace and the filesystems themselves. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-08-22sysfs: group.c: fix up kerneldocGreg Kroah-Hartman
Fix up the wording of sysfs_create/remove_groups() a bit. Reported-by: Anthony Foiani <tkil@scrye.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-21sysfs: sysfs.h: fix coding style issuesGreg Kroah-Hartman
This fixes up the remaining coding style issues in sysfs.h Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-21sysfs: file.c: fix up broken string warningsGreg Kroah-Hartman
This fixes the coding style warnings in fs/sysfs/file.c for broken strings across lines. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>