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* [patch V2 12/24] s390/kernel: Use stop_machine_cpuslocked()
       [not found] <20170418170442.665445272@linutronix.de>
@ 2017-04-18 17:04 ` Thomas Gleixner
  0 siblings, 0 replies; only message in thread
From: Thomas Gleixner @ 2017-04-18 17:04 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ingo Molnar, Steven Rostedt, Sebastian Siewior,
	Martin Schwidefsky, Heiko Carstens, David Hildenbrand, linux-s390

[-- Attachment #1: s390-kernel-Use_stop_machine_locked.patch --]
[-- Type: text/plain, Size: 1062 bytes --]

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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: linux-s390@vger.kernel.org

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

--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -636,7 +636,7 @@ static void stp_work_fn(struct work_stru
 	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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2017-04-18 17:04 ` [patch V2 12/24] s390/kernel: Use stop_machine_cpuslocked() Thomas Gleixner

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