[PATCH 1/2] drm/i915/gem: Don't flush frontbuffer in the fence signalling critical path

[Thomas Hellström]

Avoid the async clflush path if the object is a framebuffer and
instead flush sync. The frontbuffer flush takes a lock which is
allocated under in another path and thus causes a lockdep splat when
proper fence signalling annotation is added.

Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_clflush.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
index f0435c6feb68..81c536a163cf 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
@@ -20,8 +20,6 @@ static void __do_clflush(struct drm_i915_gem_object *obj)
 {
 	GEM_BUG_ON(!i915_gem_object_has_pages(obj));
 	drm_clflush_sg(obj->mm.pages);
-
-	i915_gem_object_flush_frontbuffer(obj, ORIGIN_CPU);
 }
 
 static void clflush_work(struct dma_fence_work *base)
@@ -100,7 +98,7 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
 	trace_i915_gem_object_clflush(obj);
 
 	clflush = NULL;
-	if (!(flags & I915_CLFLUSH_SYNC))
+	if (!(flags & I915_CLFLUSH_SYNC) && !i915_gem_object_is_framebuffer(obj))
 		clflush = clflush_work_create(obj);
 	if (clflush) {
 		i915_sw_fence_await_reservation(&clflush->base.chain,
@@ -111,6 +109,7 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
 		dma_fence_work_commit(&clflush->base);
 	} else if (obj->mm.pages) {
 		__do_clflush(obj);
+		i915_gem_object_flush_frontbuffer(obj, ORIGIN_CPU);
 	} else {
 		GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU);
 	}
-- 
2.31.1