linux-kernel - [PATCH 4/8] stop_machine: change stop_one_cpu() to rely on cpu_stop_queue

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Date:	Sun, 15 Nov 2015 20:33:20 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Milos Vyletel <milos@...hat.com>,
	Prarit Bhargava <prarit@...hat.com>, Tejun Heo <tj@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/8] 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@...hat.com>
---
 kernel/stop_machine.c |    6 ++++--
 1 files 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. */
-- 
1.5.5.1

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