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Commit 115ef3b7 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

watchdog/hardlockup/perf: Cure UP damage 



for_each_cpu() unintuitively reports CPU0 as set independend of the actual
cpumask content on UP kernels. That leads to a NULL pointer dereference
when the cleanup function is invoked and there is no event to clean up.

Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent ab5fe3ff

kernel/watchdog_hld.c

+6 −1
Original line number Diff line number Diff line
@@ -220,8 +220,13 @@ void hardlockup_detector_perf_cleanup(void) 
	for_each_cpu(cpu, &dead_events_mask) {

		struct perf_event *event = per_cpu(watchdog_ev, cpu);



		per_cpu(watchdog_ev, cpu) = NULL;

		/*

		 * Required because for_each_cpu() reports  unconditionally

		 * CPU0 as set on UP kernels. Sigh.

		 */

		if (event)

			perf_event_release_kernel(event);

		per_cpu(watchdog_ev, cpu) = NULL;

	}

	cpumask_clear(&dead_events_mask);

}