• P
    [PATCH] lockdep: fix ide/proc interaction · 9a2239b1
    Peter Zijlstra 提交于
      rmmod/3080 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
       (proc_subdir_lock){--..}, at: [<c04a33b0>] remove_proc_entry+0x40/0x191
    
      and this task is already holding:
       (ide_lock){++..}, at: [<c05651a2>] ide_unregister_subdriver+0x39/0xc8
      which would create a new lock dependency:
       (ide_lock){++..} -> (proc_subdir_lock){--..}
    
      but this new dependency connects a hard-irq-safe lock:
       (ide_lock){++..}
      ... which became hard-irq-safe at:
        [<c043c458>] lock_acquire+0x4b/0x6b
        [<c06129d7>] _spin_lock_irqsave+0x22/0x32
        [<c0567870>] ide_intr+0x17/0x1a9
        [<c044eb31>] handle_IRQ_event+0x20/0x4d
        [<c044ebf2>] __do_IRQ+0x94/0xef
        [<c0406771>] do_IRQ+0x9e/0xbd
    
      to a hard-irq-unsafe lock:
       (proc_subdir_lock){--..}
      ... which became hard-irq-unsafe at:
      ...  [<c043c458>] lock_acquire+0x4b/0x6b
        [<c06126ab>] _spin_lock+0x19/0x28
        [<c04a32f2>] xlate_proc_name+0x1b/0x99
        [<c04a3547>] proc_create+0x46/0xdf
        [<c04a3642>] create_proc_entry+0x62/0xa5
        [<c07c1972>] proc_misc_init+0x1c/0x1d2
        [<c07c1844>] proc_root_init+0x4c/0xe9
        [<c07ad703>] start_kernel+0x294/0x3b3
    
    Move ide_remove_proc_entries() out from under ide_lock; there is nothing
    that indicates that this is needed.
    
    In specific, the call to ide_add_proc_entries() is unprotected, and there
    is nothing else in the file using the respective ->proc fields. Also the
    lock order around destroy_proc_ide_interface() suggests this.
    
    Alan sayeth:
    
      proc_ide_write_settings walks the setting list under ide_setting_sem, read
      ditto.  remove_proc_entry is doing proc side housekeeping.
    
      Looks fine to me, although that old code is such a mess anything could be
      going on.
    Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
    Signed-off-by: NAndrew Morton <akpm@osdl.org>
    Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
    9a2239b1
ide.c 56.0 KB