From: Michal Schmidt <mschmidt@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH -rt] fix preempt count underflow in user_trace_stop
Date: Mon, 12 Mar 2007 17:03:37 +0100 [thread overview]
Message-ID: <45F579D9.7090307@redhat.com> (raw)
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 <mschmidt@redhat.com>
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;
next reply other threads:[~2007-03-12 16:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-12 16:03 Michal Schmidt [this message]
2007-03-12 16:46 ` Ingo Molnar
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