Commit f8b7530a authored Sep 05, 2018 by Neeraj Upadhyay Committed by Thomas Gleixner Sep 06, 2018

cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()



The smp_mb() in cpuhp_thread_fun() is misplaced. It needs to be after the
load of st->should_run to prevent reordering of the later load/stores
w.r.t. the load of st->should_run.

Fixes: 4dddfb5f ("smp/hotplug: Rewrite AP state machine core")
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infraded.org>
Cc: josh@joshtriplett.org
Cc: peterz@infradead.org
Cc: jiangshanlai@gmail.com
Cc: dzickus@redhat.com
Cc: brendan.jackman@arm.com
Cc: malat@debian.org
Cc: mojha@codeaurora.org
Cc: sramana@codeaurora.org
Cc: linux-arm-msm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1536126727-11629-1-git-send-email-neeraju@codeaurora.org

parent 60c1f892

kernel/cpu.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -607,15 +607,15 @@ static void cpuhp_thread_fun(unsigned int cpu)
		bool bringup = st->bringup;
		enum cpuhp_state state;

		if (WARN_ON_ONCE(!st->should_run))
		return;

		/*
		* ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
		* that if we see ->should_run we also see the rest of the state.
		*/
		smp_mb();

		if (WARN_ON_ONCE(!st->should_run))
		return;

		cpuhp_lock_acquire(bringup);

		if (st->single) {

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