On Tue, 29 Apr 2014 07:21:09 +0200
Mike Galbraith <umgwanakikbuti@xxxxxxxxx> wrote:
> On Mon, 2014-04-28 at 16:37 +0200, Mike Galbraith wrote:
>
> > > Seems that migrate_disable() must be called before taking the lock as
> > > it is done in every other location.
> >
> > And for tasklist_lock, seems you also MUST do that prior to trylock as
> > well, else you'll run afoul of the hotplug beast.
>
> Bah. Futzing with dmesg while stress script is running is either a very
> bad idea, or a very good test. Both virgin 3.10-rt and 3.12-rt with new
> bugs squashed will deadlock.
>
> Too bad I kept on testing, I liked the notion that hotplug was solid ;-)
I was able to stress cpu hotplug on 3.12-rt after applying the
following patch.
If there's no complaints about it. I'm going to add this to the 3.12-rt
stable tree. As without it, it fails horribly with the cpu hotplug
stress test, and I wont release a stable kernel that does that.
-- Steve
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
diff --git a/kernel/rt.c b/kernel/rt.c
index bb72347..4f2a613 100644
--- a/kernel/rt.c
+++ b/kernel/rt.c
@@ -180,12 +180,15 @@ EXPORT_SYMBOL(_mutex_unlock);
*/
int __lockfunc rt_write_trylock(rwlock_t *rwlock)
{
- int ret = rt_mutex_trylock(&rwlock->lock);
+ int ret;
+
+ migrate_disable();
+ ret = rt_mutex_trylock(&rwlock->lock);
- if (ret) {
+ if (ret)
rwlock_acquire(&rwlock->dep_map, 0, 1, _RET_IP_);
- migrate_disable();
- }
+ else
+ migrate_enable();
return ret;
}
@@ -212,11 +215,12 @@ int __lockfunc rt_read_trylock(rwlock_t *rwlock)
* write locked.
*/
if (rt_mutex_owner(lock) != current) {
+ migrate_disable();
ret = rt_mutex_trylock(lock);
- if (ret) {
+ if (ret)
rwlock_acquire(&rwlock->dep_map, 0, 1, _RET_IP_);
- migrate_disable();
- }
+ else
+ migrate_enable();
} else if (!rwlock->read_depth) {
ret = 0;
}
@@ -245,8 +249,8 @@ void __lockfunc rt_read_lock(rwlock_t *rwlock)
*/
if (rt_mutex_owner(lock) != current) {
rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_);
- __rt_spin_lock(lock);
migrate_disable();
+ __rt_spin_lock(lock);
}
rwlock->read_depth++;
}
--
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