From 0a0c1b823cbc0b72eb6e0c2cfe5704cf80fe842d Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Wed, 21 Jun 2017 19:10:32 -0300
Subject: [PATCH] media: rainshadow-cec: avoid -Wmaybe-uninitialized warning again
Git-commit: 0a0c1b823cbc0b72eb6e0c2cfe5704cf80fe842d
Patch-mainline: v4.13-rc4
References: bsc#1051510

Back in April I created a patch to address a false-positive warning:

Drivers/media/usb/rainshadow-cec/rainshadow-cec.c: In function 'rain_irq_work_handler':
drivers/media/usb/rainshadow-cec/rainshadow-cec.c:171:31: error: 'data' may be used uninitialized in this function [-Werror=maybe-uninitialized]

My patch was totally wrong and introduced a real bug, and Colin Ian King thankfully
noticed it now and fixed my mistake. Unfortunately, fixing the actual uninitialized
data in this case brought back the original bogus warning.

This is a new version of the patch, which simplifies the code to the point where
gcc notices the behavior is correct.

Fixes: ca33784ba494 ("[media] rainshadow-cec: ensure exit_loop is intialized")
Fixes: ea6a69defd3311 ("[media] rainshadow-cec: avoid -Wmaybe-uninitialized warning")

Cc: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/media/usb/rainshadow-cec/rainshadow-cec.c |   18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

--- a/drivers/media/usb/rainshadow-cec/rainshadow-cec.c
+++ b/drivers/media/usb/rainshadow-cec/rainshadow-cec.c
@@ -119,21 +119,19 @@ static void rain_irq_work_handler(struct
 
 	while (true) {
 		unsigned long flags;
-		bool exit_loop = false;
 		char data;
 
 		spin_lock_irqsave(&rain->buf_lock, flags);
-		if (rain->buf_len) {
-			data = rain->buf[rain->buf_rd_idx];
-			rain->buf_len--;
-			rain->buf_rd_idx = (rain->buf_rd_idx + 1) & 0xff;
-		} else {
-			exit_loop = true;
+		if (!rain->buf_len) {
+			spin_unlock_irqrestore(&rain->buf_lock, flags);
+			break;
 		}
-		spin_unlock_irqrestore(&rain->buf_lock, flags);
 
-		if (exit_loop)
-			break;
+		data = rain->buf[rain->buf_rd_idx];
+		rain->buf_len--;
+		rain->buf_rd_idx = (rain->buf_rd_idx + 1) & 0xff;
+
+		spin_unlock_irqrestore(&rain->buf_lock, flags);
 
 		if (!rain->cmd_started && data != '?')
 			continue;