Messages in this thread Patch in this message | | | Date | Mon, 6 Feb 2023 09:35:52 +0000 | Subject | Re: [PATCH] drm/i915: Move fd_install after last use of fence | From | Tvrtko Ursulin <> |
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On 03/02/2023 18:15, Rob Clark wrote: > On Fri, Feb 3, 2023 at 8:49 AM Rob Clark <robdclark@gmail.com> wrote: >> >> From: Rob Clark <robdclark@chromium.org> >> >> 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@intel.com>
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@chromium.org> >> --- >> 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 >>
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