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Subject[tip:smp/hotplug] powerpc/powernv: Use stop_machine_cpuslocked()
Commit-ID:  6e9e61778f976b52fbdeb315850ee6eb4695a1e5
Gitweb: http://git.kernel.org/tip/6e9e61778f976b52fbdeb315850ee6eb4695a1e5
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:55 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 20 Apr 2017 13:08:54 +0200

powerpc/powernv: Use stop_machine_cpuslocked()

set_subcores_per_core() 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: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20170418170553.447314339@linutronix.de

---
arch/powerpc/platforms/powernv/subcore.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/subcore.c b/arch/powerpc/platforms/powernv/subcore.c
index 0babef1..67cbf45 100644
--- a/arch/powerpc/platforms/powernv/subcore.c
+++ b/arch/powerpc/platforms/powernv/subcore.c
@@ -356,7 +356,8 @@ static int set_subcores_per_core(int new_mode)
/* Ensure state is consistent before we call the other cpus */
mb();

- stop_machine(cpu_update_split_mode, &new_mode, cpu_online_mask);
+ stop_machine_cpuslocked(cpu_update_split_mode, &new_mode,
+ cpu_online_mask);

put_online_cpus();

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