From 27ca9236c96f4a21b72a2b4f08260efeab951bd0 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 9 Feb 2016 20:11:26 +0000 Subject: [PATCH] perf/core: Remove the bogus and dangerous CPU_DOWN_FAILED hotplug state If CPU_DOWN_PREPARE fails the perf hotplug notifier is called for CPU_DOWN_FAILED and calls perf_event_init_cpu(), which checks whether the swhash is referenced. If yes it allocates a new hash and stores the pointer in the per cpu data structure. But at this point the cpu is still online, so there must be a valid hash already. By overwriting the pointer the existing hash is not longer accessible. Remove the CPU_DOWN_FAILED state, as there is nothing to (re)allocate. Signed-off-by: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Link: http://lkml.kernel.org/r/20160209201007.763417379@linutronix.de Signed-off-by: Ingo Molnar --- kernel/events/core.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 474ffea..4aa64a8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9282,7 +9282,6 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) switch (action & ~CPU_TASKS_FROZEN) { case CPU_UP_PREPARE: - case CPU_DOWN_FAILED: perf_event_init_cpu(cpu); break; -- 2.7.4