1. 23 Nov, 2013 1 commit
    • Tejun Heo's avatar
      sysfs: use a separate locking class for open files depending on mmap · 027a485d
      Tejun Heo authored
      The following two commits implemented mmap support in the regular file
      path and merged bin file support into the regular path.
      
       73d97146 ("sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.c")
       3124eb16
      
       ("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: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarDave Jones <davej@redhat.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      027a485d
  2. 01 Nov, 2013 1 commit
    • Tejun Heo's avatar
      sysfs: use generic_file_llseek() for sysfs_file_operations · 044e3bc3
      Tejun Heo authored
      13c589d5
      
       ("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: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Link: https://lkml.kernel.org/r/20131031114358.GA5551@osiris
      
      Tested-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      044e3bc3
  3. 30 Oct, 2013 1 commit
  4. 29 Oct, 2013 1 commit
    • Tejun Heo's avatar
      sysfs: merge sysfs_elem_bin_attr into sysfs_elem_attr · 56b3f3b8
      Tejun Heo authored
      3124eb16
      
       ("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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      56b3f3b8
  5. 25 Oct, 2013 1 commit
  6. 14 Oct, 2013 2 commits
    • Benjamin Herrenschmidt's avatar
      sysfs/bin: Fix size handling overflow for bin_attribute · d723a92d
      Benjamin Herrenschmidt authored
      
      
      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: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Tejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d723a92d
    • Tejun Heo's avatar
      sysfs: make sysfs_file_ops() follow ignore_lockdep flag · 785a162d
      Tejun Heo authored
      375b611e
      
       ("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: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarYinghai Lu <yinghai@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      785a162d
  7. 06 Oct, 2013 11 commits
    • Tejun Heo's avatar
      sysfs: merge regular and bin file handling · 3124eb16
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Cc: Kay Sievers <kay@vrfy.org>
      Cc: kbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3124eb16
    • Tejun Heo's avatar
      sysfs: prepare open path for unified regular / bin file handling · 49fe6047
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      49fe6047
    • Tejun Heo's avatar
      sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.c · 73d97146
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      73d97146
    • Tejun Heo's avatar
      sysfs: add sysfs_bin_read() · 2f0c6b75
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2f0c6b75
    • Tejun Heo's avatar
      sysfs: prepare path write for unified regular / bin file handling · f9b9a621
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      f9b9a621
    • Tejun Heo's avatar
      sysfs: use seq_file when reading regular files · 13c589d5
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Cc: Kay Sievers <kay@vrfy.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      13c589d5
    • Tejun Heo's avatar
      sysfs: use transient write buffer · 8ef445f0
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Cc: kbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8ef445f0
    • Tejun Heo's avatar
      sysfs: add sysfs_open_file->sd and ->file · bcafe4ee
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bcafe4ee
    • Tejun Heo's avatar
      sysfs: rename sysfs_buffer to sysfs_open_file · 58282d8d
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      58282d8d
    • Tejun Heo's avatar
      sysfs: add sysfs_open_file_mutex · c75ec764
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c75ec764
    • Tejun Heo's avatar
      sysfs: remove sysfs_buffer->ops · 375b611e
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      375b611e
  8. 05 Oct, 2013 2 commits
    • Tejun Heo's avatar
      sysfs: remove sysfs_buffer->needs_read_fill · aea585ef
      Tejun Heo authored
      
      
      ->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: default avatarTejun Heo <tj@kernel.org>
      Cc: Kay Sievers <kay@vrfy.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      aea585ef
    • Tejun Heo's avatar
      89e51dab
  9. 03 Oct, 2013 1 commit
    • Tejun Heo's avatar
      sysfs: remove sysfs_addrm_cxt->parent_sd · d69ac5a0
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d69ac5a0
  10. 26 Sep, 2013 3 commits
    • Tejun Heo's avatar
      sysfs: @name comes before @ns · cfec0bc8
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Cc: Eric W. Biederman <ebiederm@xmission.com>
      Cc: Kay Sievers <kay@vrfy.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      cfec0bc8
    • Tejun Heo's avatar
      sysfs: clean up sysfs_get_dirent() · 388975cc
      Tejun Heo authored
      
      
      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: default avatarTejun 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      388975cc
    • Tejun Heo's avatar
      sysfs: make attr namespace interface less convoluted · 58292cbe
      Tejun Heo authored
      
      
      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: default avatarTejun Heo <tj@kernel.org>
      Cc: Eric W. Biederman <ebiederm@xmission.com>
      Cc: Kay Sievers <kay@vrfy.org>
      Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      58292cbe
  11. 21 Aug, 2013 6 commits
  12. 07 Jun, 2013 1 commit
  13. 17 Jan, 2013 2 commits
  14. 27 Nov, 2012 1 commit
  15. 24 Jan, 2012 1 commit
    • Eric W. Biederman's avatar
      sysfs: Complain bitterly about attempts to remove files from nonexistent directories. · ce597919
      Eric W. Biederman authored
      
      
      Recently an OOPS was observed from the usb serial io_ti driver when it tried to remove
      sysfs directories.  Upon investigation it turns out this driver was always buggy
      and that a recent sysfs change had stopped guarding itself against removing attributes
      from sysfs directories that had already been removed. :(
      
      Historically we have been silent about attempting to files from nonexistent sysfs
      directories and have politely returned error codes.  That has resulted in people writing
      broken code that ignores the error codes.
      
      Issue a kernel WARNING and a stack backtrace to make it clear in no uncertain
      terms that abusing sysfs is not ok, and the callers need to fix their code.
      
      This change transforms the io_ti OOPS into a more comprehensible error message
      and stack backtrace.
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Reported-by: default avatarWolfgang Frisch <wfpub@roembden.net>
      Cc: stable <stable@vger.kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      ce597919
  16. 04 Jan, 2012 2 commits
  17. 19 Oct, 2011 2 commits
    • Eric W. Biederman's avatar
      sysfs: Reject with a warning invalid uses of tagged directories. · 903e21e2
      Eric W. Biederman authored
      
      
      sysfs is a core piece of ifrastructure that many people use and
      few people have all of the rules in their head on how to use
      it correctly.  Add warnings for people using tagged directories
      improperly to that any misuses can be caught and diagnosed quickly.
      
      A single inexpensive test in sysfs_find_dirent is almost sufficient
      to catch all possible misuses.  An additional warning is needed
      in sysfs_add_dirent so that we actually fail when attempting to
      add an untagged dirent in a tagged directory.
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      903e21e2
    • Eric W. Biederman's avatar
      sysfs: Implement support for tagged files in sysfs. · 487505c2
      Eric W. Biederman authored
      
      
      Looking up files in sysfs is hard to understand and analyize because we
      currently allow placing untagged files in tagged directories.  In the
      implementation of that we have two subtly different meanings of NULL.
      NULL meaning there is no tag on a directory entry and NULL meaning
      we don't care which namespace the lookup is performed for.  This
      multiple uses of NULL have resulted in subtle bugs (since fixed)
      in the code.
      
      Currently it is only the bonding driver that needs to have an untagged
      file in a tagged directory.
      
      To untagle this mess I am adding support for tagged files to sysfs.
      Modifying the bonding driver to implement bonding_masters as a tagged
      file.  Registering bonding_masters once for each network namespace.
      Then I am removing support for untagged entries in tagged sysfs
      directories.
      
      Resulting in code that is much easier to reason about.
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      487505c2
  18. 13 May, 2011 1 commit