[PATCH] pm-qos-remove-locks-around-blocking-notifier.patch ... was Re: 2.6.24-rc2-mm1

mark gross
2007-11-15T23:09:38Z

On Thu, Nov 15, 2007 at 11:19:50AM -0800, mark gross wrote:
> On Wed, Nov 14, 2007 at 12:40:08PM -0800, Andrew Morton wrote:
> > On Wed, 14 Nov 2007 12:29:59 -0800 mark gross <mgross@linux.intel.com> wrote:
> >
> > > > > [ 102.366932] =======================
> > > > > [ 108.552031] printk: 31 messages suppressed.
> > > >
> > > >
> > > > All this BUG / WARNINGS are caused by *-qos* patches. Reverting this 3 patches makes the BUGs go away :
> > > >
> > > > latencyc-use-qos-infrastructure.patch
> > > > pm-qos-infrastructure-and-interface.patch
> > > > pm-qos-infrastructure-and-interface-static-initialization-with-blocking-notifiers.patch
> > > >
> > > >
> > > > Gabriel
> > > >
> > > >
> > > This looks like the same issue Rafael saw.
> > >
> > > Try the patch in the following post:
> > >
> > > http://marc.info/?l=linux-kernel&m=119265627228498&w=2
> > >
> >
> > Well that's not very good. _I_ can go fishing in my lkml archives for random
> > patches but not everyone is set up to do that. And the diff to which you
> > refer gets 100% rejects against rc2-mm1 anyway.
> >
> > Please prepare a tested, changelogged patch against rc2-mm1 asap.
>
>
pm-qos-remove-locks-around-blocking-notifier.patch

I have done some testing with this fix, I think it addresses all the
sleep within a held lock warnings reported.

please apply.

Changelog:
Remove spin locking around all blocking notifier calls that can sleep.
I had to re-structure some of the code to avoid locking issues.

--mgross

Signed-off-by: mark gross <mgross@linux.intel.com>

Index: linux-2.6.24-rc2-mm1/kernel/pm_qos_params.c
===================================================================
--- linux-2.6.24-rc2-mm1.orig/kernel/pm_qos_params.c 2007-11-15 11:09:27.000000000 -0800
+++ linux-2.6.24-rc2-mm1/kernel/pm_qos_params.c 2007-11-15 14:10:09.000000000 -0800
@@ -135,13 +135,14 @@
}

-
-/* assumes pm_qos_lock is held */
static void update_target(int target)
{
s32 extreme_value;
struct requirement_list *node;
+ unsigned long flags;
+ int call_notifier = 0;

+ spin_lock_irqsave(&pm_qos_lock, flags);
extreme_value = pm_qos_array[target]->default_value;
list_for_each_entry(node,
&pm_qos_array[target]->requirements.list, list) {
@@ -149,13 +150,16 @@
extreme_value, node->value);
}
if (pm_qos_array[target]->target_value != extreme_value) {
+ call_notifier = 1;
pm_qos_array[target]->target_value = extreme_value;
pr_debug(KERN_ERR "new target for qos %d is %d\n", target,
pm_qos_array[target]->target_value);
- blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
- (unsigned long) pm_qos_array[target]->target_value,
- NULL);
}
+ spin_unlock_irqrestore(&pm_qos_lock, flags);
+
+ if (call_notifier)
+ blocking_notifier_call_chain(pm_qos_array[target]->notifiers,
+ (unsigned long) extreme_value, NULL);
}

static int register_pm_qos_misc(struct pm_qos_object *qos)
@@ -227,8 +231,8 @@
spin_lock_irqsave(&pm_qos_lock, flags);
list_add(&dep->list,
&pm_qos_array[pm_qos_class]->requirements.list);
- update_target(pm_qos_class);
spin_unlock_irqrestore(&pm_qos_lock, flags);
+ update_target(pm_qos_class);

return 0;
}
@@ -269,11 +273,10 @@
break;
}
}
+ spin_unlock_irqrestore(&pm_qos_lock, flags);
if (pending_update)
update_target(pm_qos_class);

- spin_unlock_irqrestore(&pm_qos_lock, flags);
-
return 0;
}
EXPORT_SYMBOL_GPL(pm_qos_update_requirement);
@@ -303,9 +306,9 @@
break;
}
}
+ spin_unlock_irqrestore(&pm_qos_lock, flags);
if (pending_update)
update_target(pm_qos_class);
- spin_unlock_irqrestore(&pm_qos_lock, flags);
}
EXPORT_SYMBOL_GPL(pm_qos_remove_requirement);

@@ -319,13 +322,10 @@
*/
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
{
- unsigned long flags;
int retval;

- spin_lock_irqsave(&pm_qos_lock, flags);
retval = blocking_notifier_chain_register(
pm_qos_array[pm_qos_class]->notifiers, notifier);
- spin_unlock_irqrestore(&pm_qos_lock, flags);

return retval;
}
@@ -341,13 +341,10 @@
*/
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
{
- unsigned long flags;
int retval;

- spin_lock_irqsave(&pm_qos_lock, flags);
retval = blocking_notifier_chain_unregister(
pm_qos_array[pm_qos_class]->notifiers, notifier);
- spin_unlock_irqrestore(&pm_qos_lock, flags);

return retval;
}