From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neeraj Upadhyay Subject: [PATCH] cpu/hotplug: Fix acquire of st->should_run in cpuhp_thread_fun() Date: Wed, 5 Sep 2018 11:22:07 +0530 Message-ID: <1536126727-11629-1-git-send-email-neeraju@codeaurora.org> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: tglx@linutronix.de, josh@joshtriplett.org, peterz@infradead.org, mingo@kernel.org, jiangshanlai@gmail.com, dzickus@redhat.com, brendan.jackman@arm.com, malat@debian.org, mojha@codeaurora.org Cc: linux-kernel@vger.kernel.org, sramana@codeaurora.org, linux-arm-msm@vger.kernel.org, Neeraj Upadhyay List-Id: linux-arm-msm@vger.kernel.org The smp_mb() in cpuhp_thread_fun() appears to be misplaced, and need 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. Signed-off-by: Neeraj Upadhyay --- kernel/cpu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index aa7fe85..eb4041f 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -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) { -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation