From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.14 014/126] cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun() Date: Tue, 18 Sep 2018 00:41:02 +0200 Message-ID: <20180917211705.614335388@linuxfoundation.org> References: <20180917211703.481236999@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180917211703.481236999@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neeraj Upadhyay , Thomas Gleixner , "Peter Zijlstra (Intel)" , josh@joshtriplett.org, peterz@infradead.org, jiangshanlai@gmail.com, dzickus@redhat.com, brendan.jackman@arm.com, malat@debian.org, mojha@codeaurora.org, sramana@codeaurora.org, linux-arm-msm@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neeraj Upadhyay commit f8b7530aa0a1def79c93101216b5b17cf408a70a upstream. 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: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Signed-off-by: Neeraj Upadhyay Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) 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 Signed-off-by: Greg Kroah-Hartman --- kernel/cpu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -612,15 +612,15 @@ static void cpuhp_thread_fun(unsigned in 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) {