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

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Message-ID: <tip-6e9e61778f976b52fbdeb315850ee6eb4695a1e5@git.kernel.org>
Date:   Thu, 20 Apr 2017 04:24:58 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     rostedt@...dmis.org, peterz@...radead.org,
        benh@...nel.crashing.org, tglx@...utronix.de, mpe@...erman.id.au,
        bigeasy@...utronix.de, linux-kernel@...r.kernel.org, hpa@...or.com,
        mingo@...nel.org
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@...utronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:55 +0200
Committer:  Thomas Gleixner <tglx@...utronix.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@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.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();