• Marek Vasut's avatar
    PCI: sysfs: Ignore lockdep for remove attribute · dc6b698a
    Marek Vasut authored
    With CONFIG_PROVE_LOCKING=y, using sysfs to remove a bridge with a device
    below it causes a lockdep warning, e.g.,
    
      # echo 1 > /sys/class/pci_bus/0000:00/device/0000:00:00.0/remove
      ============================================
      WARNING: possible recursive locking detected
      ...
      pci_bus 0000:01: busn_res: [bus 01] is released
    
    The remove recursively removes the subtree below the bridge.  Each call
    uses a different lock so there's no deadlock, but the locks were all
    created with the same lockdep key so the lockdep checker can't tell them
    apart.
    
    Mark the "remove" sysfs attribute with __ATTR_IGNORE_LOCKDEP() as it is
    safe to ignore the lockdep check between different "remove" kernfs
    instances.
    
    There's discussion about a similar issue in USB at [1], which resulted in
    356c05d5 ("sysfs: get rid of some lockdep false positives") and
    e9b526fe ("i2c: suppress lockdep warning on delete_device"), which do
    basically the same thing for USB "remove" and i2c "delete_device" files.
    
    [1] https://lore.kernel.org/r/Pine.LNX.4.44L0.1204251436140.1206-100000@iolanthe.rowland.org
    Link: https://lore.kernel.org/r/20190526225151.3865-1-marek.vasut@gmail.comSigned-off-by: default avatarMarek Vasut <marek.vasut+renesas@gmail.com>
    [bhelgaas: trim commit log, details at above links]
    Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    Cc: Geert Uytterhoeven <geert+renesas@glider.be>
    Cc: Phil Edworthy <phil.edworthy@renesas.com>
    Cc: Simon Horman <horms+renesas@verge.net.au>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Wolfram Sang <wsa@the-dreams.de>
    dc6b698a
pci-sysfs.c 42.7 KB