channel: Use frame deferral API for safe sleep.

This is another case where manual frame deferral can be replaced with
centralized routines instead.

Change-Id: I42cdf205f8f29a7977e599751a57efbaac07c30e
(cherry picked from commit d149c4b9e0)

main/channel.c

@@ -1546,19 +1546,18 @@ int ast_safe_sleep_conditional(struct ast_channel *chan, int timeout_ms, int (*c
 	int res = 0;
 	struct timeval start;
 	int ms;
-	AST_LIST_HEAD_NOLOCK(, ast_frame) deferred_frames;
-
-	AST_LIST_HEAD_INIT_NOLOCK(&deferred_frames);
 
 	/* If no other generator is present, start silencegen while waiting */
 	if (ast_opt_transmit_silence && !ast_channel_generatordata(chan)) {
 		silgen = ast_channel_start_silence_generator(chan);
 	}
 
+	ast_channel_lock(chan);
+	ast_channel_start_defer_frames(chan);
+	ast_channel_unlock(chan);
+
 	start = ast_tvnow();
 	while ((ms = ast_remaining_ms(start, timeout_ms))) {
-		struct ast_frame *dup_f = NULL;
-
 		if (cond && ((*cond)(data) == 0)) {
 			break;
 		}
@@ -1573,18 +1572,7 @@ int ast_safe_sleep_conditional(struct ast_channel *chan, int timeout_ms, int (*c
 				res = -1;
 				break;
 			}
-
-			if (!ast_is_deferrable_frame(f)) {
-				ast_frfree(f);
-				continue;
-			}
-
-			if ((dup_f = ast_frisolate(f))) {
-				if (dup_f != f) {
-					ast_frfree(f);
-				}
-				AST_LIST_INSERT_HEAD(&deferred_frames, dup_f, frame_list);
-			}
+			ast_frfree(f);
 		}
 	}
 
@@ -1593,17 +1581,8 @@ int ast_safe_sleep_conditional(struct ast_channel *chan, int timeout_ms, int (*c
 		ast_channel_stop_silence_generator(chan, silgen);
 	}
 
-	/* We need to free all the deferred frames, but we only need to
-	 * queue the deferred frames if there was no error and no
-	 * hangup was received
-	 */
 	ast_channel_lock(chan);
-	while ((f = AST_LIST_REMOVE_HEAD(&deferred_frames, frame_list))) {
-		if (!res) {
-			ast_queue_frame_head(chan, f);
-		}
-		ast_frfree(f);
-	}
+	ast_channel_stop_defer_frames(chan);
 	ast_channel_unlock(chan);
 
 	return res;