[PATCH 7/8] stop_machine: shift the done != NULL check from cpu_stop_signal_done() to callers

Oleg Nesterov
2015-11-15T18:38:06Z

Change cpu_stop_queue_work() and cpu_stopper_thread() to check done != NULL
before cpu_stop_signal_done(done). This makes the code more clean imo, note
that cpu_stopper_thread() has to do this check anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/stop_machine.c | 18 ++++++++----------
1 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 09eb83f..7ff7ace 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -64,10 +64,8 @@ static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
/* signal completion unless @done is NULL */
static void cpu_stop_signal_done(struct cpu_stop_done *done)
{
- if (done) {
- if (atomic_dec_and_test(&done->nr_todo))
- complete(&done->completion);
- }
+ if (atomic_dec_and_test(&done->nr_todo))
+ complete(&done->completion);
}

static void __cpu_stop_queue_work(struct cpu_stopper *stopper,
@@ -88,7 +86,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
enabled = stopper->enabled;
if (enabled)
__cpu_stop_queue_work(stopper, work);
- else
+ else if (work->done)
cpu_stop_signal_done(work->done);
spin_unlock_irqrestore(&stopper->lock, flags);

@@ -457,12 +455,12 @@ repeat:

/* cpu stop callbacks are not allowed to sleep */
preempt_disable();
-
ret = fn(arg);
- if (ret && done)
- done->ret = ret;
- cpu_stop_signal_done(done);
-
+ if (done) {
+ if (ret)
+ done->ret = ret;
+ cpu_stop_signal_done(done);
+ }
/* restore preemption and check it's still balanced */
preempt_enable();
WARN_ONCE(preempt_count(),
--
1.5.5.1