drm/msm: Track "seqno" fences by idr

Previously the (non-fd) fence returned from submit ioctl was a raw
seqno, which is scoped to the ring.  But from UABI standpoint, the
ioctls related to seqno fences all specify a submitqueue.  We can
take advantage of that to replace the seqno fences with a cyclic idr
handle.

This is in preperation for moving to drm scheduler, at which point
the submit ioctl will return after queuing the submit job to the
scheduler, but before the submit is written into the ring (and
therefore before a ring seqno has been assigned).  Which means we
need to replace the dma_fence that userspace may need to wait on
with a scheduler fence.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20210728010632.2633470-8-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

1 files changed, 28 insertions, 2 deletions

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 9b8fa2ad0d84..1594ae39d54f 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -911,6 +911,7 @@ static int msm_ioctl_wait_fence(struct drm_device *dev, void *data,
 	ktime_t timeout = to_ktime(args->timeout);
 	struct msm_gpu_submitqueue *queue;
 	struct msm_gpu *gpu = priv->gpu;
+	struct dma_fence *fence;
 	int ret;
 
 	if (args->pad) {
@@ -925,10 +926,35 @@ static int msm_ioctl_wait_fence(struct drm_device *dev, void *data,
 	if (!queue)
 		return -ENOENT;
 
-	ret = msm_wait_fence(gpu->rb[queue->prio]->fctx, args->fence, &timeout,
-		true);
+	/*
+	 * Map submitqueue scoped "seqno" (which is actually an idr key)
+	 * back to underlying dma-fence
+	 *
+	 * The fence is removed from the fence_idr when the submit is
+	 * retired, so if the fence is not found it means there is nothing
+	 * to wait for
+	 */
+	ret = mutex_lock_interruptible(&queue->lock);
+	if (ret)
+		return ret;
+	fence = idr_find(&queue->fence_idr, args->fence);
+	if (fence)
+		fence = dma_fence_get_rcu(fence);
+	mutex_unlock(&queue->lock);
+
+	if (!fence)
+		return 0;
 
+	ret = dma_fence_wait_timeout(fence, true, timeout_to_jiffies(&timeout));
+	if (ret == 0) {
+		ret = -ETIMEDOUT;
+	} else if (ret != -ERESTARTSYS) {
+		ret = 0;
+	}
+
+	dma_fence_put(fence);
 	msm_submitqueue_put(queue);
+
 	return ret;
 }