• 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