drm/i915: Pull waiting on an external dma-fence into its routine

As a means for a small code consolidation, but primarily to start
thinking more carefully about internal-vs-external linkage, pull the
pair of i915_sw_fence_await_dma_fence() calls into a common routine.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200508092933.738-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_request.c

@@ -1067,6 +1067,14 @@ i915_request_await_request(struct i915_request *to, struct i915_request *from)
 	return 0;
 }
 
+static int
+i915_request_await_external(struct i915_request *rq, struct dma_fence *fence)
+{
+	return i915_sw_fence_await_dma_fence(&rq->submit, fence,
+					     fence->context ? I915_FENCE_TIMEOUT : 0,
+					     I915_FENCE_GFP);
+}
+
 int
 i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
 {
@@ -1114,9 +1122,7 @@ i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
 		if (dma_fence_is_i915(fence))
 			ret = i915_request_await_request(rq, to_request(fence));
 		else
-			ret = i915_sw_fence_await_dma_fence(&rq->submit, fence,
-							    fence->context ? I915_FENCE_TIMEOUT : 0,
-							    I915_FENCE_GFP);
+			ret = i915_request_await_external(rq, fence);
 		if (ret < 0)
 			return ret;
 
@@ -1255,9 +1261,7 @@ i915_request_await_execution(struct i915_request *rq,
 							     to_request(fence),
 							     hook);
 		else
-			ret = i915_sw_fence_await_dma_fence(&rq->submit, fence,
-							    I915_FENCE_TIMEOUT,
-							    GFP_KERNEL);
+			ret = i915_request_await_external(rq, fence);
 		if (ret < 0)
 			return ret;
 	} while (--nchild);