On 29/01/2026 12:53, Christian König wrote:
When the memory allocated by userspace isn't sufficient for all the
fences then just wait on them instead of returning an error.
Hmm..
Signed-off-by: Christian König <[email protected]>
---
.../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 52 ++++++++++---------
1 file changed, 28 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
index ee8a5fbbd53b..d059712741fb 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
@@ -734,7 +734,7 @@ amdgpu_userq_wait_count_fences(struct drm_file *filp,
num_fences++;
}
- wait_info->num_fences = num_fences;
+ wait_info->num_fences = min(num_fences, USHRT_MAX);
Oh it is actually a weakness in the uapi with wait_info->num_fences
being u16. I did not pick that from the commit message straight away.
De-dup the array when over the uapi limit, and retry?
Is it userq fences or other fences that cause the spill in practice? If
the former then the patch adds a kernel wait where there wasn't one
before so de-duping more aggressively could maybe limit that path.
Regards,
Tvrtko
r = 0;
error_unlock:
@@ -743,6 +743,19 @@ amdgpu_userq_wait_count_fences(struct drm_file *filp,
return r;
}
+static int
+amdgpu_userq_wait_add_fence(struct drm_amdgpu_userq_wait *wait_info,
+ struct dma_fence **fences, unsigned int *num_fences,
+ struct dma_fence *fence)
+{
+ /* As fallback shouldn't userspace allocate enough space */
+ if (*num_fences >= wait_info->num_fences)
+ return dma_fence_wait(fence, true);
+
+ fences[(*num_fences)++] = dma_fence_get(fence);
+ return 0;
+}
+
static int
amdgpu_userq_wait_return_fence_info(struct drm_file *filp,
struct drm_amdgpu_userq_wait *wait_info,
@@ -786,12 +799,10 @@ amdgpu_userq_wait_return_fence_info(struct drm_file *filp,
goto free_fences;
dma_fence_unwrap_for_each(f, &iter, fence) {
- if (num_fences >= wait_info->num_fences) {
- r = -EINVAL;
+ r = amdgpu_userq_wait_add_fence(wait_info, fences,
+ &num_fences, f);
+ if (r)
goto free_fences;
- }
-
- fences[num_fences++] = dma_fence_get(f);
}
dma_fence_put(fence);
@@ -808,12 +819,11 @@ amdgpu_userq_wait_return_fence_info(struct drm_file *filp,
if (r)
goto free_fences;
- if (num_fences >= wait_info->num_fences) {
- r = -EINVAL;
+ r = amdgpu_userq_wait_add_fence(wait_info, fences,
+ &num_fences, f);
+ if (r)
goto free_fences;
- }
- fences[num_fences++] = fence;
dma_fence_put(fence);
}
@@ -844,13 +854,10 @@ amdgpu_userq_wait_return_fence_info(struct drm_file *filp,
dma_resv_for_each_fence(&resv_cursor, gobj_read[i]->resv,
DMA_RESV_USAGE_READ, fence) {
- if (num_fences >= wait_info->num_fences) {
- r = -EINVAL;
- goto error_unlock;
- }
-
- fences[num_fences++] = fence;
- dma_fence_get(fence);
+ r = amdgpu_userq_wait_add_fence(wait_info, fences,
+ &num_fences, f);
+ if (r)
+ goto free_fences;
}
}
@@ -861,13 +868,10 @@ amdgpu_userq_wait_return_fence_info(struct drm_file *filp,
dma_resv_for_each_fence(&resv_cursor, gobj_write[i]->resv,
DMA_RESV_USAGE_WRITE, fence) {
- if (num_fences >= wait_info->num_fences) {
- r = -EINVAL;
- goto error_unlock;
- }
-
- fences[num_fences++] = fence;
- dma_fence_get(fence);
+ r = amdgpu_userq_wait_add_fence(wait_info, fences,
+ &num_fences, f);
+ if (r)
+ goto free_fences;
}
}
