From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: Lucas Stach <l.stach@pengutronix.de>,
Eric Anholt <eric@anholt.net>,
dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/3] drm/v3d: Take a lock across GPU scheduler job creation and queuing.
Date: Wed, 6 Jun 2018 10:52:07 +0200 [thread overview]
Message-ID: <6462aaec-a5f3-3a78-2eb1-fb24faa68e42@gmail.com> (raw)
In-Reply-To: <1528274797.26063.6.camel@pengutronix.de>
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
next prev parent reply other threads:[~2018-06-06 8:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-05 19:03 [PATCH 1/3] drm/v3d: Take a lock across GPU scheduler job creation and queuing Eric Anholt
2018-06-05 19:03 ` [PATCH 2/3] drm/v3d: Remove the bad signaled() implementation Eric Anholt
2018-06-08 10:21 ` Lucas Stach
2018-06-05 19:03 ` [PATCH 3/3] drm/v3d: Add a note about locking of v3d_fence_create() Eric Anholt
2018-06-08 10:24 ` Lucas Stach
2018-06-08 17:08 ` Eric Anholt
2018-06-06 8:46 ` [PATCH 1/3] drm/v3d: Take a lock across GPU scheduler job creation and queuing Lucas Stach
2018-06-06 8:52 ` Christian König [this message]
2018-06-06 17:48 ` [PATCH 1/3 v2] " Eric Anholt
2018-06-07 8:37 ` Lucas Stach
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