drm/i915: Serialise execbuf operation after a dma-buf reservation object

Now that we can wait upon fences before emitting the request, it becomes
trivial to wait upon any implicit fence provided by the dma-buf
reservation object.

To protect against failure, we force any asynchronous waits on a foreign
fence to timeout after 10s - so that a stall in another driver does not
permanently cripple ourselves. Still unpleasant though!

Testcase: igt/prime_vgem/fence-wait
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: John Harrison <john.c.harrison@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-21-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index ccaf15ba4e3227a45cde1e419957517888a0535b..33c85227643dbc04cc377ea374146ecd6e3804b5 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1131,6 +1131,7 @@ i915_gem_execbuffer_move_to_gpu(struct drm_i915_gem_request *req,
 
        list_for_each_entry(vma, vmas, exec_list) {
                struct drm_i915_gem_object *obj = vma->obj;
+               struct reservation_object *resv;
 
                if (obj->flags & other_rings) {
                        ret = i915_gem_request_await_object
@@ -1139,6 +1140,16 @@ i915_gem_execbuffer_move_to_gpu(struct drm_i915_gem_request *req,
                                return ret;
                }
 
+               resv = i915_gem_object_get_dmabuf_resv(obj);
+               if (resv) {
+                       ret = i915_sw_fence_await_reservation
+                               (&req->submit, resv, &i915_fence_ops,
+                                obj->base.pending_write_domain, 10*HZ,
+                                GFP_KERNEL | __GFP_NOWARN);
+                       if (ret < 0)
+                               return ret;
+               }
+
                if (obj->base.write_domain & I915_GEM_DOMAIN_CPU)
                        i915_gem_clflush_object(obj, false);
        }