On Thu, 2005-08-25 at 21:59 +0800, Yingchao Zhou wrote:
> In stop_machine function, there are codes:
> if (ret < 0) {
> stopmachine_set_state(STOPMACHINE_EXIT);
> up(&stopmachine_mutex);
> return ret;
> }
> And in __stop_machine_run ,there are:
> if (!IS_ERR(p)) {
> kthread_bind(p, cpu);
> wake_up_process(p);
> wait_for_completion(&smdata.done);
> }
> up(&stopmachine_mutex);
>
> Is the first up op is really redundant?
Yes, it seems you have found a bug. I tested it (inserting a spurious
failure), and indeed, it gets up'ed twice.
Good catch!
Rusty.
Name: Redundant up operation in stop_machine.c
Signed-off-by: Rusty Russell <[email protected]> (authored)
Yingchao Zhou <[email protected]> noticed that we up() in
stop_machine on failure, and also in the caller (unconditionally).
Index: linux-2.6.13-rc7-git1-Misc/kernel/stop_machine.c
===================================================================
--- linux-2.6.13-rc7-git1-Misc.orig/kernel/stop_machine.c 2005-08-26 11:18:00.000000000 +1000
+++ linux-2.6.13-rc7-git1-Misc/kernel/stop_machine.c 2005-08-26 12:05:01.000000000 +1000
@@ -115,7 +115,6 @@
/* If some failed, kill them all. */
if (ret < 0) {
stopmachine_set_state(STOPMACHINE_EXIT);
- up(&stopmachine_mutex);
return ret;
}
--
A bad analogy is like a leaky screwdriver -- Richard Braakman
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