[patch v2 2/4] stop_machine: reorganize stop_cpus() implementation

From: Suresh Siddha
Date: Thu Jun 23 2011 - 14:23:31 EST


From: Tejun Heo <tj@xxxxxxxxxx>

Refactor the queuing part of the stop cpus work from __stop_cpus() into
queue_stop_cpus_work().

The reorganization is to help future improvements to stop_machine()
and doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
kernel/stop_machine.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

Index: linux-2.6-tip/kernel/stop_machine.c
===================================================================
--- linux-2.6-tip.orig/kernel/stop_machine.c
+++ linux-2.6-tip/kernel/stop_machine.c
@@ -136,10 +136,11 @@ DEFINE_MUTEX(stop_cpus_mutex);
/* static data for stop_cpus */
static DEFINE_PER_CPU(struct cpu_stop_work, stop_cpus_work);

-int __stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
+static void queue_stop_cpus_work(const struct cpumask *cpumask,
+ cpu_stop_fn_t fn, void *arg,
+ struct cpu_stop_done *done)
{
struct cpu_stop_work *work;
- struct cpu_stop_done done;
unsigned int cpu;

/* initialize works and done */
@@ -147,9 +148,8 @@ int __stop_cpus(const struct cpumask *cp
work = &per_cpu(stop_cpus_work, cpu);
work->fn = fn;
work->arg = arg;
- work->done = &done;
+ work->done = done;
}
- cpu_stop_init_done(&done, cpumask_weight(cpumask));

/*
* Disable preemption while queueing to avoid getting
@@ -161,7 +161,15 @@ int __stop_cpus(const struct cpumask *cp
cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu),
&per_cpu(stop_cpus_work, cpu));
preempt_enable();
+}

+static int __stop_cpus(const struct cpumask *cpumask,
+ cpu_stop_fn_t fn, void *arg)
+{
+ struct cpu_stop_done done;
+
+ cpu_stop_init_done(&done, cpumask_weight(cpumask));
+ queue_stop_cpus_work(cpumask, fn, arg, &done);
wait_for_completion(&done.completion);
return done.executed ? done.ret : -ENOENT;
}


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