Re: 2.6.24-rc2-mm1

[mark gross <mgross@linux.intel.com>]

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.  

I'm having difficulty coming up with a .config that boots, I'll continue
working on this but the following is what I'm pretty confident will fix
the warnings.  

You should hold off until I get a system booting 2.6.24-rc2-mm1 before
taking this.

pm-qos-remove-locks-around-blocking-notifier-registration.patch

Changelog: 
Remove spin locking around blocking notifier calls that can sleep.

--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 11:10:08.000000000 -0800
@@ -319,13 +319,10 @@
  */
  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 +338,10 @@
  */
 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;
 }
-
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