Messages in this thread Patch in this message | | | Date | Fri, 18 Nov 2011 15:12:48 -0800 | From | tip-bot for Gleb Natapov <> | Subject | [tip:perf/core] jump_label: jump_label_inc may return before the code is patched |
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Commit-ID: c8452afb7426f7e21388492f40227582e3e83879 Gitweb: http://git.kernel.org/tip/c8452afb7426f7e21388492f40227582e3e83879 Author: Gleb Natapov <gleb@redhat.com> AuthorDate: Tue, 18 Oct 2011 19:55:51 +0200 Committer: Steven Rostedt <rostedt@goodmis.org> CommitDate: Mon, 7 Nov 2011 11:02:34 -0500
jump_label: jump_label_inc may return before the code is patched
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 a8ce450..e6f1f24 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(); }
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