lkml.org 
[lkml]   [2018]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/3] drm/v3d: Take a lock across GPU scheduler job creation and queuing.
From
Date
Am 06.06.2018 um 10:46 schrieb Lucas Stach:
> Am Dienstag, den 05.06.2018, 12:03 -0700 schrieb Eric Anholt:
>> Between creation and queueing of a job, you need to prevent any other
>> job from being created and queued.  Otherwise the scheduler's fences
>> may be signaled out of seqno order.
>>
>>> Signed-off-by: Eric Anholt <eric@anholt.net>
>> Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")
>> ---
>>
>> ccing amd-gfx due to interaction of this series with the scheduler.
>>
>>  drivers/gpu/drm/v3d/v3d_drv.h |  5 +++++
>>  drivers/gpu/drm/v3d/v3d_gem.c | 11 +++++++++--
>>  2 files changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
>> index a043ac3aae98..26005abd9c5d 100644
>> --- a/drivers/gpu/drm/v3d/v3d_drv.h
>> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
>> @@ -85,6 +85,11 @@ struct v3d_dev {
>>>    */
>>>   struct mutex reset_lock;
>>
>>> + /* Lock taken when creating and pushing the GPU scheduler
>>> +  * jobs, to keep the sched-fence seqnos in order.
>>> +  */
>>> + struct mutex sched_lock;
>> +
>>>   struct {
>>>   u32 num_allocated;
>>>   u32 pages_allocated;
>> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
>> index b513f9189caf..9ea83bdb9a30 100644
>> --- a/drivers/gpu/drm/v3d/v3d_gem.c
>> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
>> @@ -550,13 +550,16 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
>>>   if (ret)
>>>   goto fail;
>>
>>> + mutex_lock(&v3d->sched_lock);
>>>   if (exec->bin.start != exec->bin.end) {
>>>   ret = drm_sched_job_init(&exec->bin.base,
>>>    &v3d->queue[V3D_BIN].sched,
>>>    &v3d_priv->sched_entity[V3D_BIN],
>>>    v3d_priv);
>>> - if (ret)
>>> + if (ret) {
>>> + mutex_unlock(&v3d->sched_lock);
>>   goto fail_unreserve;
> I don't see any path where you would go to fail_unreserve with the
> mutex not yet locked, so you could just fold the mutex_unlock into this
> error path for a bit less code duplication.
>
> Otherwise this looks fine.

Yeah, agree that could be cleaned up.

I can't judge the correctness of the driver, but at least the scheduler
handling looks good to me.

Regards,
Christian.

>
> Regards,
> Lucas
>
>> + }
>>
>>>   exec->bin_done_fence =
>>>   dma_fence_get(&exec->bin.base.s_fence->finished);
>> @@ -570,12 +573,15 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
>>>    &v3d->queue[V3D_RENDER].sched,
>>>    &v3d_priv->sched_entity[V3D_RENDER],
>>>    v3d_priv);
>>> - if (ret)
>>> + if (ret) {
>>> + mutex_unlock(&v3d->sched_lock);
>>>   goto fail_unreserve;
>>> + }
>>
>>>   kref_get(&exec->refcount); /* put by scheduler job completion */
>>>   drm_sched_entity_push_job(&exec->render.base,
>>>     &v3d_priv->sched_entity[V3D_RENDER]);
>>> + mutex_unlock(&v3d->sched_lock);
>>
>>>   v3d_attach_object_fences(exec);
>>
>> @@ -615,6 +621,7 @@ v3d_gem_init(struct drm_device *dev)
>>>   spin_lock_init(&v3d->job_lock);
>>>   mutex_init(&v3d->bo_lock);
>>>   mutex_init(&v3d->reset_lock);
>>> + mutex_init(&v3d->sched_lock);
>>
>>>   /* Note: We don't allocate address 0.  Various bits of HW
>>>    * treat 0 as special, such as the occlusion query counters
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

\
 
 \ /
  Last update: 2018-06-06 10:52    [W:0.087 / U:3.732 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site