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drm/msm: move submit fence wait out of struct_mutex 

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
signalled.

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@gmail.com>
This commit is contained in:
Rob Clark 2017-02-25 10:36:30 -05:00
parent cc69272673
commit 48f243c95b
1 changed files with 18 additions and 21 deletions
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39
drivers/gpu/drm/msm/msm_gem_submit.c
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@ -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)