From 9140096a5b039dcdfbb0a005f4b9e6b17eb3123e Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Tue, 18 Oct 2011 19:55:51 +0200 Subject: jump_label: jump_label_inc may return before the code is patched commit bbbf7af4bf8fc69bc751818cf30521080fa47dcb upstream. 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: Peter Zijlstra Acked-by: Jason Baron Signed-off-by: Gleb Natapov Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/jump_label.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/jump_label.c b/kernel/jump_label.c index a8ce45097f3..e6f1f24ad57 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(); } -- cgit v1.2.3-18-g5258