perf/core: Remove the bogus and dangerous CPU_DOWN_FAILED hotplug state
authorThomas Gleixner <tglx@linutronix.de>
Tue, 9 Feb 2016 20:11:26 +0000 (20:11 +0000)
committerIngo Molnar <mingo@kernel.org>
Wed, 17 Feb 2016 09:37:29 +0000 (10:37 +0100)
commit4b15c7438222a4342fda9130af9793fa1bf09814
treee0409b083e3709c1b6e735704df145fb4c14e3f1
parent978c3e22d4a25ac702a2166a20c5e2a5fe6706ad
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 <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.763417379@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/events/core.c