linux-kernel - [tip:smp/hotplug] s390/kernel: Use stop_machine

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Message-ID: <tip-35cc1ac5c24cb497b3b15a9383ff098e4a8bf03c@git.kernel.org>
Date:   Thu, 20 Apr 2017 04:24:27 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, peterz@...radead.org, dahi@...ux.vnet.ibm.com,
        schwidefsky@...ibm.com, bigeasy@...utronix.de, rostedt@...dmis.org,
        linux-kernel@...r.kernel.org, hpa@...or.com,
        heiko.carstens@...ibm.com, tglx@...utronix.de
Subject: [tip:smp/hotplug] s390/kernel: Use stop_machine_cpuslocked()

Commit-ID:  35cc1ac5c24cb497b3b15a9383ff098e4a8bf03c
Gitweb:     http://git.kernel.org/tip/35cc1ac5c24cb497b3b15a9383ff098e4a8bf03c
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:54 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 20 Apr 2017 13:08:54 +0200

s390/kernel: Use stop_machine_cpuslocked()

stp_work_fn() holds get_online_cpus() while invoking stop_machine().

stop_machine() invokes get_online_cpus() as well. This is correct, but
prevents the conversion of the hotplug locking to a percpu rwsem.

Use stop_machine_cpuslocked() to avoid the nested call.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-s390@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: David Hildenbrand <dahi@...ux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Link: http://lkml.kernel.org/r/20170418170553.363283884@linutronix.de

---
 arch/s390/kernel/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index c31da46..3aa8acb 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -636,7 +636,7 @@ static void stp_work_fn(struct work_struct *work)
 	memset(&stp_sync, 0, sizeof(stp_sync));
 	get_online_cpus();
 	atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
-	stop_machine(stp_sync_clock, &stp_sync, cpu_online_mask);
+	stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
 	put_online_cpus();
 
 	if (!check_sync_clock())