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Commit 5568b139 authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
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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: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas 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;

}