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| author | Gleb Natapov <gleb@redhat.com> | 2011-10-18 19:55:51 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-12-09 08:52:50 -0800 |
| commit | 9140096a5b039dcdfbb0a005f4b9e6b17eb3123e (patch) | |
| tree | a78847c0bd04fbdb4f3d15c9589f379919c3087b | |
| parent | 248f3235861683bb1ffc7316b56bf783b162666f (diff) | |
| download | lwn-9140096a5b039dcdfbb0a005f4b9e6b17eb3123e.tar.gz lwn-9140096a5b039dcdfbb0a005f4b9e6b17eb3123e.zip | |
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 <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>
| -rw-r--r-- | 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 a8ce45097f3d..e6f1f24ad577 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(); } |