drm/i915/selftests: Fix locking inversion in lrc selftest.

This function does not use intel_context_create_request, so it has
to use the same locking order as normal code. This is required to
shut up lockdep in selftests.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200819140904.1708856-20-maarten.lankhorst@linux.intel.comSigned-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/gt/selftest_lrc.c

@@ -4996,6 +4996,7 @@ static int __live_lrc_state(struct intel_engine_cs *engine,
 {
 	struct intel_context *ce;
 	struct i915_request *rq;
+	struct i915_gem_ww_ctx ww;
 	enum {
 		RING_START_IDX = 0,
 		RING_TAIL_IDX,
@@ -5010,7 +5011,11 @@ static int __live_lrc_state(struct intel_engine_cs *engine,
 	if (IS_ERR(ce))
 		return PTR_ERR(ce);
 
-	err = intel_context_pin(ce);
+	i915_gem_ww_ctx_init(&ww, false);
+retry:
+	err = i915_gem_object_lock(scratch->obj, &ww);
+	if (!err)
+		err = intel_context_pin_ww(ce, &ww);
 	if (err)
 		goto err_put;
 
@@ -5039,11 +5044,9 @@ static int __live_lrc_state(struct intel_engine_cs *engine,
 	*cs++ = i915_ggtt_offset(scratch) + RING_TAIL_IDX * sizeof(u32);
 	*cs++ = 0;
 
-	i915_vma_lock(scratch);
 	err = i915_request_await_object(rq, scratch->obj, true);
 	if (!err)
 		err = i915_vma_move_to_active(scratch, rq, EXEC_OBJECT_WRITE);
-	i915_vma_unlock(scratch);
 
 	i915_request_get(rq);
 	i915_request_add(rq);
@@ -5080,6 +5083,12 @@ static int __live_lrc_state(struct intel_engine_cs *engine,
 err_unpin:
 	intel_context_unpin(ce);
 err_put:
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
 	intel_context_put(ce);
 	return err;
 }