linux-kernel - [tip:smp/hotplug] x86/mtrr: Remove get_online_cpus() from mtrr_save

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Message-ID: <tip-9ef0b62e7059e3ea85e2e5c4894bc2cb78b04eed@git.kernel.org>
Date:   Thu, 20 Apr 2017 04:20:54 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, rostedt@...dmis.org,
        peterz@...radead.org, mingo@...nel.org, tglx@...utronix.de,
        bigeasy@...utronix.de, hpa@...or.com
Subject: [tip:smp/hotplug] x86/mtrr: Remove get_online_cpus() from
 mtrr_save_state()

Commit-ID:  9ef0b62e7059e3ea85e2e5c4894bc2cb78b04eed
Gitweb:     http://git.kernel.org/tip/9ef0b62e7059e3ea85e2e5c4894bc2cb78b04eed
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:47 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 20 Apr 2017 13:08:51 +0200

x86/mtrr: Remove get_online_cpus() from mtrr_save_state()

mtrr_save_state() is invoked from native_cpu_up() which is in the context
of a CPU hotplug operation and therefor calling get_online_cpus() is
pointless.

While this works in the current get_online_cpus() implementation it
prevents from converting the hotplug locking to percpu rwsems.

Remove it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Link: http://lkml.kernel.org/r/20170418170552.775914295@linutronix.de

---
 arch/x86/kernel/cpu/mtrr/main.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 24e87e7..8fd1f8d 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -807,10 +807,8 @@ void mtrr_save_state(void)
 	if (!mtrr_enabled())
 		return;
 
-	get_online_cpus();
 	first_cpu = cpumask_first(cpu_online_mask);
 	smp_call_function_single(first_cpu, mtrr_save_fixed_ranges, NULL, 1);
-	put_online_cpus();
 }
 
 void set_mtrr_aps_delayed_init(void)