From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Christian_K=c3=b6nig?= 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 Message-ID: <6462aaec-a5f3-3a78-2eb1-fb24faa68e42@gmail.com> References: <20180605190302.18279-1-eric@anholt.net> <1528274797.26063.6.camel@pengutronix.de> Reply-To: christian.koenig@amd.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <1528274797.26063.6.camel@pengutronix.de> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Lucas Stach , Eric Anholt , dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org List-Id: amd-gfx.lists.freedesktop.org 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 >> 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