Re: [PATCH] drm/i915: add missing rpm ref to i915_gem_pwrite_ioctl

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 16 Dec 2014, Imre Deak <imre.deak@intel.com> wrote:
> On Wed, 2014-11-12 at 16:40 +0200, Imre Deak wrote:
>> Without this RPM ref we can hit the device suspended WARN via:
>> i915_gem_object_pin()->ggtt_bind_vma->gen6_ggtt_insert_entries(). I
>> noticed this on my BYT while keeping the i915 device in runtime
>> suspended state for a while. I chose this place to take the ref to
>> avoid the possible deadlock via the mutex_lock taken both later in this
>> function and in the runtime suspend handler. This can happen if an RPM
>> suspend event is queued and need to be flushed before taking the RPM
>> ref.
>
> Testcase: igt/pm_rpm/gem-evict-pwrite
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87363

Pushed to drm-intel-next-fixes, thanks for the patch.

BR,
Jani.

>
>> Signed-off-by: Imre Deak <imre.deak@intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_gem.c | 8 +++++++-
>>  1 file changed, 7 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>> index 86cf428..ec2ee28 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -1075,6 +1075,7 @@ int
>>  i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
>>  		      struct drm_file *file)
>>  {
>> +	struct drm_i915_private *dev_priv = dev->dev_private;
>>  	struct drm_i915_gem_pwrite *args = data;
>>  	struct drm_i915_gem_object *obj;
>>  	int ret;
>> @@ -1094,9 +1095,11 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
>>  			return -EFAULT;
>>  	}
>>  
>> +	intel_runtime_pm_get(dev_priv);
>> +
>>  	ret = i915_mutex_lock_interruptible(dev);
>>  	if (ret)
>> -		return ret;
>> +		goto put_rpm;
>>  
>>  	obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
>>  	if (&obj->base == NULL) {
>> @@ -1148,6 +1151,9 @@ out:
>>  	drm_gem_object_unreference(&obj->base);
>>  unlock:
>>  	mutex_unlock(&dev->struct_mutex);
>> +put_rpm:
>> +	intel_runtime_pm_put(dev_priv);
>> +
>>  	return ret;
>>  }
>>  
>
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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