From: Gleb Natapov <gleb@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Jason Baron <jbaron@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH] jump_label_inc may return before the code is patched
Date: Tue, 18 Oct 2011 19:55:51 +0200 [thread overview]
Message-ID: <20111018175551.GH17571@redhat.com> (raw)
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.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
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();
}
--
Gleb.
next reply other threads:[~2011-10-18 17:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-18 17:55 Gleb Natapov [this message]
2011-10-18 20:54 ` [PATCH] jump_label_inc may return before the code is patched Jason Baron
2011-10-19 7:03 ` Gleb Natapov
2011-10-18 21:06 ` Steven Rostedt
2011-11-02 15:21 ` Gleb Natapov
2011-11-02 15:42 ` Steven Rostedt
2011-11-18 23:12 ` [tip:perf/core] jump_label: " tip-bot for Gleb Natapov
2011-12-06 6:27 ` tip-bot for Gleb Natapov
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