Probably a symptom of needing finer grained locking, but if we wait on
the incoming fence-fd (which could come from a different context) while
holding struct_mutex, that blocks retire_worker so gpu fences cannot get
scheduled.
This causes a problem if userspace manages to get more than a frame
ahead, leaving the atomic-commit worker blocked waiting on fences that
cannot be signaled because submit is blocked waiting for a fence
signalled from vblank (after the atomic commit which is blocked).
If we start having multiple fence ctxs for the gpu, submit_fence_sync()
would probably need to move outside of struct_mutex as well.
Signed-off-by: Rob Clark <robdclark@xxxxxxxxx>
---
drivers/gpu/drm/msm/msm_gem_submit.c | 39 +++++++++++++++++-------------------
1 file changed, 18 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 1172fe7..1c545eb 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -404,6 +404,24 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
if (MSM_PIPE_FLAGS(args->flags) & ~MSM_SUBMIT_FLAGS)
return -EINVAL;
+ if (args->flags & MSM_SUBMIT_FENCE_FD_IN) {
+ in_fence = sync_file_get_fence(args->fence_fd);
+
+ if (!in_fence)
+ return -EINVAL;
+
+ /* TODO if we get an array-fence due to userspace merging multiple
+ * fences, we need a way to determine if all the backing fences
+ * are from our own context..
+ */
+
+ if (in_fence->context != gpu->fctx->context) {
+ ret = dma_fence_wait(in_fence, true);
+ if (ret)
+ return ret;
+ }
+ }
+
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
@@ -431,27 +449,6 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
if (ret)
goto out;
- if (args->flags & MSM_SUBMIT_FENCE_FD_IN) {
- in_fence = sync_file_get_fence(args->fence_fd);
-
- if (!in_fence) {
- ret = -EINVAL;
- goto out;
- }
-
- /* TODO if we get an array-fence due to userspace merging multiple
- * fences, we need a way to determine if all the backing fences
- * are from our own context..
- */
-
- if (in_fence->context != gpu->fctx->context) {
- ret = dma_fence_wait(in_fence, true);
- if (ret)
- goto out;
- }
-
- }
-
if (!(args->fence & MSM_SUBMIT_NO_IMPLICIT)) {
ret = submit_fence_sync(submit);
if (ret)
--
2.9.3
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