[PATCH 2/2] drm/dp/mst: take lock around looking up the branch device on hpd irq

[Jani Nikula]

On Mon, 22 Jun 2015, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Mon, Jun 22, 2015 at 02:40:44PM +1000, Dave Airlie wrote:
>> From: Dave Airlie <airlied at redhat.com>
>> 
>> If we are doing an MST transaction and we've gotten HPD and we
>> lookup the device from the incoming msg, we should take the mgr
>> lock around it, so that mst_primary and mstb->ports are valid.
>> 
>> Signed-off-by: Dave Airlie <airlied at redhat.com>
>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

The error path fails to unlock the mutex, reported in [1]. There's a fix
in the bug, I've asked Adam to post it to the list.

BR,
Jani.


[1] https://bugs.freedesktop.org/show_bug.cgi?id=92480


>
>> ---
>>  drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
>>  1 file changed, 3 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
>> index 3c7e5cd..15a6d8e 100644
>> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
>> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
>> @@ -1175,6 +1175,8 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
>>  	struct drm_dp_mst_port *port;
>>  	int i;
>>  	/* find the port by iterating down */
>> +
>> +	mutex_lock(&mgr->lock);
>>  	mstb = mgr->mst_primary;
>>  
>>  	for (i = 0; i < lct - 1; i++) {
>> @@ -1194,6 +1196,7 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
>>  		}
>>  	}
>>  	kref_get(&mstb->kref);
>> +	mutex_unlock(&mgr->lock);
>>  	return mstb;
>>  }
>>  
>> -- 
>> 2.4.1
>> 
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>
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
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> dri-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Jani Nikula, Intel Open Source Technology Center