drm/i915/gt: Hold request reference while waiting for w/a verification

As we wait upon a request, we must be holding a reference to it, and be
wary that i915_request_add() consumes the passed in reference.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191121093326.134774-1-chris@chris-wilson.co.uk

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

@@ -1592,16 +1592,17 @@ static int engine_wa_list_verify(struct intel_context *ce,
 	if (err)
 		goto err_vma;
 
+	i915_request_get(rq);
 	i915_request_add(rq);
 	if (i915_request_wait(rq, 0, HZ / 5) < 0) {
 		err = -ETIME;
-		goto err_vma;
+		goto err_rq;
 	}
 
 	results = i915_gem_object_pin_map(vma->obj, I915_MAP_WB);
 	if (IS_ERR(results)) {
 		err = PTR_ERR(results);
-		goto err_vma;
+		goto err_rq;
 	}
 
 	err = 0;
@@ -1615,6 +1616,8 @@ static int engine_wa_list_verify(struct intel_context *ce,
 
 	i915_gem_object_unpin_map(vma->obj);
 
+err_rq:
+	i915_request_put(rq);
 err_vma:
 	i915_vma_unpin(vma);
 	i915_vma_put(vma);