On 03/02/2023 18:15, Rob Clark wrote:
On Fri, Feb 3, 2023 at 8:49 AM Rob Clark <robdclark@xxxxxxxxx> wrote:
From: Rob Clark <robdclark@xxxxxxxxxxxx>
Because eb_composite_fence_create() drops the fence_array reference
after creation of the sync_file, only the sync_file holds a ref to the
fence. But fd_install() makes that reference visable to userspace, so
it must be the last thing we do with the fence.
Fixes: 00dae4d3d35d ("drm/i915: Implement SINGLE_TIMELINE with a syncobj (v4)")
This is correct and the fix looks good to me.
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
CI is green so I will merge it, thanks again for a fix Rob!
Followup up question for Matthew Brost however is whether the composite
fence flow could be simplified. This block here comes late in
i915_gem_do_execbuffer and may mislead the user the composite fence is
held to the end of the function:
if (!out_fence && eb.composite_fence)
dma_fence_put(eb.composite_fence);
Question is would it work to remove the !out_fence condition from here,
and remove "consumption" of the reference from eb_composite_fence_create
success path.
Regards,
Tvrtko
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index f266b68cf012..0f2e056c02dd 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -3476,38 +3476,38 @@ i915_gem_do_execbuffer(struct drm_device *dev,
err_request:
eb_requests_get(&eb);
err = eb_requests_add(&eb, err);
if (eb.fences)
signal_fence_array(&eb, eb.composite_fence ?
eb.composite_fence :
&eb.requests[0]->fence);
+ if (unlikely(eb.gem_context->syncobj)) {
+ drm_syncobj_replace_fence(eb.gem_context->syncobj,
+ eb.composite_fence ?
+ eb.composite_fence :
+ &eb.requests[0]->fence);
+ }
+
if (out_fence) {
if (err == 0) {
fd_install(out_fence_fd, out_fence->file);
args->rsvd2 &= GENMASK_ULL(31, 0); /* keep in-fence */
args->rsvd2 |= (u64)out_fence_fd << 32;
out_fence_fd = -1;
} else {
fput(out_fence->file);
}
}
- if (unlikely(eb.gem_context->syncobj)) {
- drm_syncobj_replace_fence(eb.gem_context->syncobj,
- eb.composite_fence ?
- eb.composite_fence :
- &eb.requests[0]->fence);
- }
-
if (!out_fence && eb.composite_fence)
dma_fence_put(eb.composite_fence);
eb_requests_put(&eb);
err_vma:
eb_release_vmas(&eb, true);
WARN_ON(err == -EDEADLK);
i915_gem_ww_ctx_fini(&eb.ww);
--
2.38.1
