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From: Arnd Bergmann <arnd@arndb.de>
To: Alessandro Zummo <a.zummo@towertech.it>
Cc: rtc-linux@googlegroups.com, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH] rtc: pcf8563: fix uninitialized use warning
Date: Sun, 07 Sep 2014 22:42:43 +0200	[thread overview]
Message-ID: <3640058.m4Rfp1dmTJ@wuerfel> (raw)

gcc-4.9 found a potential condition under which the 'pending'
variable may be used uninitialized:

drivers/rtc/rtc-pcf8563.c: In function 'pcf8563_irq':
drivers/rtc/rtc-pcf8563.c:173:5: warning: 'pending' may be used uninitialized in this function [-Wmaybe-uninitialized]

This is because in the pcf8563_get_alarm_mode() function, we
check any nonzero return of pcf8563_read_block_data, but
in the irq function we only check for negative values, so
a possible positive value does not get detected if the compiler
chooses not to inline the entire call chain.

Checking for any non-zero value in the interrupt handler as well
is just as correct and lets the compiler know what we are doing,
without needing a bogus initialization.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index 5a197d9dc7e7..3a6f994c4da8 100644
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -167,7 +167,7 @@ static irqreturn_t pcf8563_irq(int irq, void *dev_id)
 	char pending;
 
 	err = pcf8563_get_alarm_mode(pcf8563->client, NULL, &pending);
-	if (err < 0)
+	if (err)
 		return err;
 
 	if (pending) {


WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] rtc: pcf8563: fix uninitialized use warning
Date: Sun, 07 Sep 2014 22:42:43 +0200	[thread overview]
Message-ID: <3640058.m4Rfp1dmTJ@wuerfel> (raw)

gcc-4.9 found a potential condition under which the 'pending'
variable may be used uninitialized:

drivers/rtc/rtc-pcf8563.c: In function 'pcf8563_irq':
drivers/rtc/rtc-pcf8563.c:173:5: warning: 'pending' may be used uninitialized in this function [-Wmaybe-uninitialized]

This is because in the pcf8563_get_alarm_mode() function, we
check any nonzero return of pcf8563_read_block_data, but
in the irq function we only check for negative values, so
a possible positive value does not get detected if the compiler
chooses not to inline the entire call chain.

Checking for any non-zero value in the interrupt handler as well
is just as correct and lets the compiler know what we are doing,
without needing a bogus initialization.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index 5a197d9dc7e7..3a6f994c4da8 100644
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -167,7 +167,7 @@ static irqreturn_t pcf8563_irq(int irq, void *dev_id)
 	char pending;
 
 	err = pcf8563_get_alarm_mode(pcf8563->client, NULL, &pending);
-	if (err < 0)
+	if (err)
 		return err;
 
 	if (pending) {

             reply	other threads:[~2014-09-07 20:43 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-07 20:42 Arnd Bergmann [this message]
2014-09-07 20:42 ` [PATCH] rtc: pcf8563: fix uninitialized use warning Arnd Bergmann
2014-09-08 11:02 ` Sergei Shtylyov
2014-09-08 11:02   ` Sergei Shtylyov
2014-09-08 15:22   ` Arnd Bergmann
2014-09-08 15:22     ` Arnd Bergmann
2014-09-08 15:40     ` Sergei Shtylyov
2014-09-08 15:40       ` Sergei Shtylyov

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