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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@linutronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:54 +0200
Committer: Thomas Gleixner <tglx@linutronix.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@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-s390@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.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())
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