drm/i915: Move fd_install after last use of fence

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.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Fixes: 00dae4d3 ("drm/i915: Implement SINGLE_TIMELINE with a syncobj (v4)")
Cc: <stable@vger.kernel.org> # v5.15+
[tursulin: Added stable tag.]
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230203164937.4035503-1-robdclark@gmail.com

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -3486,6 +3486,13 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 				   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);
@@ -3497,13 +3504,6 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 		}
 	}
 
-	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);