Re: [PATCH] kthread: convert stop_machine into a kthread

[Serge E. Hallyn]

Quoting Andrew Morton (akpm@xxxxxxxx):
> On Tue, 20 Jun 2006 03:27:45 -0500
> "Serge E. Hallyn" <serue@xxxxxxxxxx> wrote:
> 
> > Ah, like so?
> 
> Nope.  kthread_bind() is supposed to be called by the thread creator,
> before the thread is started.
> 
> The documentation for kthread_bind() is irritatingly hidden in the header
> file.

Oh, I see - then it makes more sense that it gets away with being so
much simpler than set_cpus_allowed().

So here's another attempt.  However I'm not sure now whether
the first round of synchronization around stopmachine_thread_ack
is necessary anymore.  If any threads fail, we'll find out from the
kthread_create() return value, right?

Still I'm not sure about that, so first things first:

thanks,
-serge

From: Serge E. Hallyn <serue@xxxxxxxxxx>
Date: Tue, 20 Jun 2006 11:01:08 -0500
Subject: [PATCH] kthread: update stop_machine to use kthread_bind

Update stop_machine to use the more efficient kthread_bind()
before running task in place of set_cpus_allowed() after.

Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>

---

 kernel/stop_machine.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

e25a88e3d60f3f139f10cc8cd894d87622033a16
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 2dd5a48..593d8e4 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -86,7 +86,8 @@ static void stopmachine_set_state(enum s
 
 static int stop_machine(void)
 {
-	int i, ret = 0;
+	int ret = 0;
+	unsigned int i;
 	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 
 	/* One high-prio thread per cpu.  We'll do this one. */
@@ -100,11 +101,13 @@ static int stop_machine(void)
 		struct task_struct *tsk;
 		if (i == raw_smp_processor_id())
 			continue;
-		tsk = kthread_run(stopmachine, (void *)(long)i, "stopmachine");
+		tsk = kthread_create(stopmachine, NULL, "stopmachine");
 		if (IS_ERR(tsk)) {
 			ret = PTR_ERR(tsk);
 			break;
 		}
+		kthread_bind(tsk, i);
+		wake_up_process(tsk);
 		stopmachine_num_threads++;
 	}
 
-- 
1.3.3

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