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jump_label: jump_label_inc may return before the code is patched

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If cpu A calls jump_label_inc() just after atomic_add_return() is
called by cpu B, atomic_inc_not_zero() will return value greater then
zero and jump_label_inc() will return to a caller before jump_label_update()
finishes its job on cpu B.

Link: http://lkml.kernel.org/r/20111018175551.GH17571@redhat.com

Cc: stable@vger.kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Gleb Natapov 2011-10-18 19:55:51 +02:00 committed by Steven Rostedt
parent 8ee3c92b7f
commit c8452afb74
1 changed files with 2 additions and 1 deletions
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3
kernel/jump_label.c
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@ -66,8 +66,9 @@ void jump_label_inc(struct jump_label_key *key)
return;
jump_label_lock();
if (atomic_add_return(1, &key->enabled) == 1)
if (atomic_read(&key->enabled) == 0)
jump_label_update(key, JUMP_LABEL_ENABLE);
atomic_inc(&key->enabled);
jump_label_unlock();
}