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@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: der.herr@hofr.at
Cc: paulmck@linux.vnet.ibm.com
Cc: riel@redhat.com
Cc: viro@ZenIV.linux.org.uk
Link: http://lkml.kernel.org/r/20150630012948.GA23927@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 6e677b003164fa9e0997cbe4ce59665aaee8aea3..621220852df007d13b134fac624cadd0f17654d3 100644 (file)
--- 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);
 }