| Message ID | 3640058.m4Rfp1dmTJ@wuerfel |
|---|---|
| State | Superseded |
| Headers | show |
Hello. On 9/8/2014 12:42 AM, Arnd Bergmann wrote: > 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; Returning negative values from the IRQ handler doesn't seem valid. Arbitrary positive value aren't good either. Perhaps should return IRQ_NONE instead? WBR, Sergei
On Monday 08 September 2014 15:02:00 Sergei Shtylyov wrote: > > 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; > > Returning negative values from the IRQ handler doesn't seem valid. > Arbitrary positive value aren't good either. Perhaps should return IRQ_NONE > instead? Good point. This is unrelated to the problem I was trying to fix, but it seems like a good idea to fix both. Arnd
On 9/8/2014 7:22 PM, Arnd Bergmann wrote: >>> 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; >> Returning negative values from the IRQ handler doesn't seem valid. >> Arbitrary positive value aren't good either. Perhaps should return IRQ_NONE >> instead? > Good point. This is unrelated to the problem I was trying to fix, but it > seems like a good idea to fix both. Then it would be good if you fix this issue with a separate patch. > Arnd WBR, Sergei
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) {
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>