Messages in this thread Patch in this message | | | Date | Wed, 07 Dec 2011 08:12:43 -0800 | From | Greg KH <> | Subject | [101/104] jump_label: jump_label_inc may return before the code is patched |
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3.1-stable review patch. If anyone has any objections, please let me know.
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From: Gleb Natapov <gleb@redhat.com>
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 <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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/jump_label.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -66,8 +66,9 @@ void jump_label_inc(struct jump_label_ke 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(); }
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