Commit 5568b139 authored May 12, 2008 by Steven Rostedt Committed by Thomas Gleixner May 23, 2008

ftrace: debug smp_processor_id, use notrace preempt disable



The debug smp_processor_id caused a recursive fault in debugging
the irqsoff tracer. The tracer used a smp_processor_id in the
ftrace callback, and this function called preempt_disable which
also is traced. This caused a recursive fault (stack overload).

Since using smp_processor_id without debugging on does not cause
faults with the tracer (even when the tracer is wrong), the
debug version should not cause a system reboot.

This changes the debug_smp_processor_id to use the notrace versions
of preempt_disable and enable.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent f43fdad8

lib/smp_processor_id.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -37,7 +37,7 @@ notrace unsigned int debug_smp_processor_id(void)
		/*
		* Avoid recursion:
		*/
		preempt_disable();
		preempt_disable_notrace();

		if (!printk_ratelimit())
		goto out_enable;
		@@ -49,7 +49,7 @@ notrace unsigned int debug_smp_processor_id(void)
		dump_stack();

		out_enable:
		preempt_enable_no_resched();
		preempt_enable_no_resched_notrace();
		out:
		return this_cpu;
		}

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