gpiolib: cdev: Refactor allocation of linereq events kfifo

The allocation of the linereq events kfifo is performed in two separate
places.  Add a helper function to remove the duplication.
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20240529131953.195777-3-warthog618@gmail.comSigned-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpiolib-cdev.c

@@ -1128,6 +1128,14 @@ static void edge_detector_stop(struct line *line)
 	/* do not change line->level - see comment in debounced_value() */
 }
 
+static int edge_detector_fifo_init(struct linereq *req)
+{
+	if (kfifo_initialized(&req->events))
+		return 0;
+
+	return kfifo_alloc(&req->events, req->event_buffer_size, GFP_KERNEL);
+}
+
 static int edge_detector_setup(struct line *line,
 			       struct gpio_v2_line_config *lc,
 			       unsigned int line_idx, u64 edflags)
@@ -1139,9 +1147,8 @@ static int edge_detector_setup(struct line *line,
 	char *label;
 
 	eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS;
-	if (eflags && !kfifo_initialized(&line->req->events)) {
-		ret = kfifo_alloc(&line->req->events,
-				  line->req->event_buffer_size, GFP_KERNEL);
+	if (eflags) {
+		ret = edge_detector_fifo_init(line->req);
 		if (ret)
 			return ret;
 	}
@@ -1193,8 +1200,6 @@ static int edge_detector_update(struct line *line,
 				struct gpio_v2_line_config *lc,
 				unsigned int line_idx, u64 edflags)
 {
-	u64 eflags;
-	int ret;
 	u64 active_edflags = READ_ONCE(line->edflags);
 	unsigned int debounce_period_us =
 			gpio_v2_line_config_debounce_period(lc, line_idx);
@@ -1210,14 +1215,9 @@ static int edge_detector_update(struct line *line,
 		 * ensure event fifo is initialised if edge detection
 		 * is now enabled.
 		 */
-		eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS;
-		if (eflags && !kfifo_initialized(&line->req->events)) {
-			ret = kfifo_alloc(&line->req->events,
-					  line->req->event_buffer_size,
-					  GFP_KERNEL);
-			if (ret)
-				return ret;
-		}
+		if (edflags & GPIO_V2_LINE_EDGE_FLAGS)
+			return edge_detector_fifo_init(line->req);
+
 		return 0;
 	}