From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030472AbXCLQEG (ORCPT ); Mon, 12 Mar 2007 12:04:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030481AbXCLQEG (ORCPT ); Mon, 12 Mar 2007 12:04:06 -0400 Received: from mx1.redhat.com ([66.187.233.31]:59722 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030472AbXCLQEE (ORCPT ); Mon, 12 Mar 2007 12:04:04 -0400 Message-ID: <45F579D9.7090307@redhat.com> Date: Mon, 12 Mar 2007 17:03:37 +0100 From: Michal Schmidt User-Agent: Icedove 1.5.0.10 (X11/20070306) MIME-Version: 1.0 To: Ingo Molnar CC: Thomas Gleixner , linux-kernel Subject: [PATCH -rt] fix preempt count underflow in user_trace_stop Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org When playing with trace_user_trigger_irq in order to trace IRQ->userspace latencies, I encountered a bug in the latency tracer. If I have wakeup_timing enabled and attempt to stop the trace in my userspace program, the system crashes. This is caused by an unbalanced preempt_enable() which underflows the preempt count. Signed-off-by: Michal Schmidt diff --git a/kernel/latency_trace.c b/kernel/latency_trace.c index e07bb95..29dfb79 100644 --- a/kernel/latency_trace.c +++ b/kernel/latency_trace.c @@ -2396,7 +2396,6 @@ long user_trace_stop(void) if (current != sch.task) { __raw_spin_unlock(&sch.trace_lock); local_irq_restore(flags); - preempt_enable(); return -EINVAL; } sch.task = NULL;