diff options
| author | Christian König | 2023-09-08 10:27:23 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2023-10-19 23:08:57 +0200 |
| commit | d67b5a2b97b6e8959117ff71fc2daa30e66c8290 (patch) | |
| tree | 8226e937a3b951b0255c1144811197a74c649e60 /include/linux | |
| parent | cb8f1dd1b73cce453b38ce92da884d379daad3ad (diff) | |
dma-buf: add dma_fence_timestamp helper
commit b83ce9cb4a465b8f9a3fa45561b721a9551f60e3 upstream.
When a fence signals there is a very small race window where the timestamp
isn't updated yet. sync_file solves this by busy waiting for the
timestamp to appear, but on other ocassions didn't handled this
correctly.
Provide a dma_fence_timestamp() helper function for this and use it in
all appropriate cases.
Another alternative would be to grab the spinlock when that happens.
v2 by teddy: add a wait parameter to wait for the timestamp to show up, in case
the accurate timestamp is needed and/or the timestamp is not based on
ktime (e.g. hw timestamp)
v3 chk: drop the parameter again for unified handling
Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: 1774baa64f93 ("drm/scheduler: Change scheduled fence track v2")
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
CC: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20230929104725.2358-1-christian.koenig@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/dma-fence.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index be572c3a4dcd..3dfb994312b1 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -548,6 +548,25 @@ static inline void dma_fence_set_error(struct dma_fence *fence, fence->error = error; } +/** + * dma_fence_timestamp - helper to get the completion timestamp of a fence + * @fence: fence to get the timestamp from. + * + * After a fence is signaled the timestamp is updated with the signaling time, + * but setting the timestamp can race with tasks waiting for the signaling. This + * helper busy waits for the correct timestamp to appear. + */ +static inline ktime_t dma_fence_timestamp(struct dma_fence *fence) +{ + if (WARN_ON(!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))) + return ktime_get(); + + while (!test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags)) + cpu_relax(); + + return fence->timestamp; +} + signed long dma_fence_wait_timeout(struct dma_fence *, bool intr, signed long timeout); signed long dma_fence_wait_any_timeout(struct dma_fence **fences, |