linux-kernel - [PATCH 3/3] auxdisplay: img-ascii-lcd: Silence 2 uninitialized warnings

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Message-ID: <20180219160956.6uky4zxlnn5kas2t@gmail.com>
Date:   Mon, 19 Feb 2018 17:09:56 +0100
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     linux-kernel@...r.kernel.org, paul.burton@...s.com,
        geert@...ux-m68k.org
Subject: [PATCH 3/3] auxdisplay: img-ascii-lcd: Silence 2 uninitialized
 warnings

The warnings are:

  drivers/auxdisplay/img-ascii-lcd.c: warning: 'err' may be used
  uninitialized in this function [-Wuninitialized]

At lines 109 and 207. Reported by Geert using the build service
several times, e.g.:

  https://lkml.org/lkml/2018/2/19/303

They are two false positives, since num_chars > 0 in the three present
configurations (boston, malta, sead3). Initializing to an error state by
default silences the warning and makes the code print an error in case a
num_chars == 0 happens in the future (unlikely, since it does not make
sense currently).

The warnings seem to disappear starting with gcc >= 4.9

Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Paul Burton <paul.burton@...s.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
---
I will queue it up for 4.17.

drivers/auxdisplay/img-ascii-lcd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index d8133024fd5d..bd5ebb5c516c 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -97,7 +97,7 @@ static struct img_ascii_lcd_config boston_config = {
 static void malta_update(struct img_ascii_lcd_ctx *ctx)
 {
 	unsigned int i;
-	int err;
+	int err = 1;
 
 	for (i = 0; i < ctx->cfg->num_chars; i++) {
 		err = regmap_write(ctx->regmap,
@@ -180,7 +180,7 @@ static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
 static void sead3_update(struct img_ascii_lcd_ctx *ctx)
 {
 	unsigned int i;
-	int err;
+	int err = 1;
 
 	for (i = 0; i < ctx->cfg->num_chars; i++) {
 		err = sead3_wait_lcd_idle(ctx);
-- 
2.14.1