[tip:sched/core] stop_machine: Don't do for_each_cpu() twice in queue_stop_cpus_work()

From: tip-bot for Oleg Nesterov
Date: Mon Aug 03 2015 - 13:09:59 EST


Commit-ID: b377c2a089d4538e6e62e51fa595c896c314d83d
Gitweb: http://git.kernel.org/tip/b377c2a089d4538e6e62e51fa595c896c314d83d
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 30 Jun 2015 03:29:48 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Aug 2015 12:21:26 +0200

stop_machine: Don't do for_each_cpu() twice in queue_stop_cpus_work()

queue_stop_cpus_work() can do everything in one for_each_cpu() loop.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: dave@xxxxxxxxxxxx
Cc: der.herr@xxxxxxx
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: riel@xxxxxxxxxx
Cc: viro@xxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20150630012948.GA23927@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/stop_machine.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 6e677b0..6212208 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -303,22 +303,19 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask,
struct cpu_stop_work *work;
unsigned int cpu;

- /* initialize works and done */
- for_each_cpu(cpu, cpumask) {
- work = &per_cpu(cpu_stopper.stop_work, cpu);
- work->fn = fn;
- work->arg = arg;
- work->done = done;
- }
-
/*
* Disable preemption while queueing to avoid getting
* preempted by a stopper which might wait for other stoppers
* to enter @fn which can lead to deadlock.
*/
lg_global_lock(&stop_cpus_lock);
- for_each_cpu(cpu, cpumask)
- cpu_stop_queue_work(cpu, &per_cpu(cpu_stopper.stop_work, cpu));
+ for_each_cpu(cpu, cpumask) {
+ work = &per_cpu(cpu_stopper.stop_work, cpu);
+ work->fn = fn;
+ work->arg = arg;
+ work->done = done;
+ cpu_stop_queue_work(cpu, work);
+ }
lg_global_unlock(&stop_cpus_lock);
}

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