ocfs2: cluster: fix potential deadlock on &o2net_debug_lock

&o2net_debug_lock is acquired by timer o2net_idle_timer() along the
following call chain.  Thus the acquisition of the lock under process
context should disable bottom half, otherwise deadlock could happen if the
timer happens to preempt the execution while the lock is held in process
context on the same CPU.

<timer interrupt>
        -> o2net_idle_timer()
        -> queue_delayed_work()
        -> sc_put()
        -> sc_kref_release()
        -> o2net_debug_del_sc()
        -> spin_lock(&o2net_debug_lock);

Several lock acquisition of &o2net_debug_lock under process context do not
disable irq or bottom half.  The patch fixes these potential deadlocks
scenerio by using spin_lock_bh() on &o2net_debug_lock.

This flaw was found by an experimental static analysis tool I am
developing for irq-related deadlock.  x86_64 allmodconfig using gcc shows
no new warning.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Chengfeng Ye <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Joseph Qi <[email protected]>
Cc: Gang He <[email protected]>
Cc: Jun Piao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions