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Message-ID: <20100515214256.GA3506@thegnar.org>
Date: Sat, 15 May 2010 14:42:56 -0700
From: mgross <markgross@...gnar.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: markgross@...gnar.org, Valdis.Kletnieks@...eu,
mgross@...ux.intel.com, akpm@...ux-foundation.org,
davem@...emloft.net, linux-kernel@...r.kernel.org,
e1000-devel@...ts.sourceforge.net, netdev@...r.kernel.org,
linux-pm@...ts.linux-foundation.org
Subject: Re: [patch] pm_qos update fixing mmotm 2010-05-11 -dies in
pm_qos_update_request()
On Sat, May 15, 2010 at 09:38:47PM +0200, Rafael J. Wysocki wrote:
> On Saturday 15 May 2010, mgross wrote:
> > I apologize for the goofy email address.
> >
> > The following is a fix for the crash reported by Valdis.
> >
> > The problem was that the original pm_qos silently fails when a request
> > update is passed to a parameter that has not been added to the list
> > yet. It seems that the e1000e is doing this. This update restores this
> > behavior.
> >
> > I need to think about how to better handle such abuse, but for now this
> > restores the original behavior.
>
> Can you please post a signed-off incremental patch against
>
> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6.git for-llinus
>
> that contains your original PM QOS update?
>
> Thanks,
> Rafael
>
No problem:
Signed-off-by: markgross <markgross@...gnar.org>
--mgross
>From 487b8dcaeb66d3c226d4c06c1bd99689f93024be Mon Sep 17 00:00:00 2001
From: mgross <mgross@...oss-desktop.(none)>
Date: Sat, 15 May 2010 14:30:15 -0700
Subject: [PATCH] Gard against pm_qos users calling API before registering a proper
request.
This update handles a use case where pm_qos update requests need to
silently fail if the update is being sent to a handle that is null.
The problem was that the original pm_qos silently fails when a request
update is passed to a parameter that has not been added to the list yet.
This update restores that behavior.
Signed-off-by: markgross <markgross@...gnar.org>
---
kernel/pm_qos_params.c | 26 ++++++++++++++------------
1 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index a1aea04..f42d3f7 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -252,19 +252,21 @@ void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
int pending_update = 0;
s32 temp;
- spin_lock_irqsave(&pm_qos_lock, flags);
- if (new_value == PM_QOS_DEFAULT_VALUE)
- temp = pm_qos_array[pm_qos_req->pm_qos_class]->default_value;
- else
- temp = new_value;
-
- if (temp != pm_qos_req->value) {
- pending_update = 1;
- pm_qos_req->value = temp;
+ if (pm_qos_req) { /*guard against callers passing in null */
+ spin_lock_irqsave(&pm_qos_lock, flags);
+ if (new_value == PM_QOS_DEFAULT_VALUE)
+ temp = pm_qos_array[pm_qos_req->pm_qos_class]->default_value;
+ else
+ temp = new_value;
+
+ if (temp != pm_qos_req->value) {
+ pending_update = 1;
+ pm_qos_req->value = temp;
+ }
+ spin_unlock_irqrestore(&pm_qos_lock, flags);
+ if (pending_update)
+ update_target(pm_qos_req->pm_qos_class);
}
- spin_unlock_irqrestore(&pm_qos_lock, flags);
- if (pending_update)
- update_target(pm_qos_req->pm_qos_class);
}
EXPORT_SYMBOL_GPL(pm_qos_update_request);
--
1.6.3.3
--
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