Messages in this thread Patch in this message | | | Date | Mon, 05 Dec 2011 20:41:14 -0500 | From | Steven Rostedt <> | Subject | [PATCH 4/6] jump_label: jump_label_inc may return before the code is patched |
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From: Gleb Natapov <gleb@redhat.com>
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> --- kernel/jump_label.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index bbdfe2a..66ff710 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -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(); } -- 1.7.7.3
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