[tip:sched/core] stop_machine: Change stop_one_cpu() to rely on cpu_stop_queue_work()

tip-bot for Oleg Nesterov
2015-11-23T16:23:07Z

Commit-ID: 958c5f848e17e216df138cc2161b07b7120e2d15
Gitweb: http://git.kernel.org/tip/958c5f848e17e216df138cc2161b07b7120e2d15
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Sun, 15 Nov 2015 20:33:20 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 23 Nov 2015 09:48:18 +0100

stop_machine: Change stop_one_cpu() to rely on cpu_stop_queue_work()

Change stop_one_cpu() to return -ENOENT if cpu_stop_queue_work() fails.
Otherwise we know that ->executed must be true after wait_for_completion()
so we can just return done.ret.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Milos Vyletel <milos@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20151115193320.GA8259@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/stop_machine.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 0ec1f16..68b73c4 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -128,9 +128,11 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };

cpu_stop_init_done(&done, 1);
- cpu_stop_queue_work(cpu, &work);
+ if (!cpu_stop_queue_work(cpu, &work))
+ return -ENOENT;
wait_for_completion(&done.completion);
- return done.executed ? done.ret : -ENOENT;
+ WARN_ON(!done.executed);
+ return done.ret;
}

/* This controls the threads on each CPU. */