| Message ID | 1469877735-30127-1-git-send-email-robert.jarzmik@free.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, 2016-07-30 at 13:22 +0200, Robert Jarzmik wrote: > The commit 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of > gpio register") from Oct 17, 2011, leads to the following static checker > warning: > arch/arm/mach-pxa/spitz_pm.c:172 spitz_charger_wakeup() > warn: double left shift '!gpio_get_value(SPITZ_GPIO_KEY_INT) > << (1 << ((SPITZ_GPIO_KEY_INT) & 31))' > > As Dan reported, the value is shifted three times : > - once by gpio_get_value(), which returns either 0 or BIT(gpio) > - once by the shift operation '<<' > - a last time by GPIO_bit(gpio) which is BIT(gpio) > > Therefore the calculation lead to a chained or operator of : > - (1 << gpio) << (1 << gpio) = (2^gpio)^gpio = 2 ^ (gpio * gpio) > > It is be sheer luck the former statement works, only because each gpio > used is strictly smaller than 6, and therefore 2^(gpio^2) never > overflows a 32 bits value, and because it is used as a boolean value to > check a gpio activation. It may be better to change the charger_wakeup callback return value from unsigned long to bool and modify the other use in spitz_pm.c $ git grep -w charger_wakeup arch/arm/mach-pxa/corgi_pm.c: .charger_wakeup = corgi_charger_wakeup, arch/arm/mach-pxa/sharpsl_pm.c: if (sharpsl_pm.machinfo->charger_wakeup() != 0) arch/arm/mach-pxa/sharpsl_pm.c: if (sharpsl_pm.machinfo->charger_wakeup()) arch/arm/mach-pxa/sharpsl_pm.h: unsigned long (*charger_wakeup)(void); arch/arm/mach-pxa/spitz_pm.c: .charger_wakeup = spitz_charger_wakeup, > Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of > gpio register") > Reported-by: Dan Carpenter <dan.carpenter@oracle.com> > Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr> > --- > Since v1: replaced binary ORs with logical ORs after assembly comparison > --- > arch/arm/mach-pxa/corgi_pm.c | 8 +++----- > arch/arm/mach-pxa/spitz_pm.c | 5 ++--- > 2 files changed, 5 insertions(+), 8 deletions(-) > > diff --git a/arch/arm/mach-pxa/corgi_pm.c b/arch/arm/mach-pxa/corgi_pm.c > index d9206811be9b..8dc39d602884 100644 > --- a/arch/arm/mach-pxa/corgi_pm.c > +++ b/arch/arm/mach-pxa/corgi_pm.c > @@ -135,11 +135,9 @@ static unsigned long corgi_charger_wakeup(void) > { > unsigned long ret; > > - ret = (!gpio_get_value(CORGI_GPIO_AC_IN) << GPIO_bit(CORGI_GPIO_AC_IN)) > - | (!gpio_get_value(CORGI_GPIO_KEY_INT) > - << GPIO_bit(CORGI_GPIO_KEY_INT)) > - | (!gpio_get_value(CORGI_GPIO_WAKEUP) > - << GPIO_bit(CORGI_GPIO_WAKEUP)); > + ret = !gpio_get_value(CORGI_GPIO_AC_IN) > + || !gpio_get_value(CORGI_GPIO_KEY_INT) > + || !gpio_get_value(CORGI_GPIO_WAKEUP); > return ret; > } > > diff --git a/arch/arm/mach-pxa/spitz_pm.c b/arch/arm/mach-pxa/spitz_pm.c > index ea9f9034cb54..dd85869f6f99 100644 > --- a/arch/arm/mach-pxa/spitz_pm.c > +++ b/arch/arm/mach-pxa/spitz_pm.c > @@ -168,9 +168,8 @@ static int spitz_should_wakeup(unsigned int resume_on_alarm) > static unsigned long spitz_charger_wakeup(void) > { > unsigned long ret; > - ret = ((!gpio_get_value(SPITZ_GPIO_KEY_INT) > - << GPIO_bit(SPITZ_GPIO_KEY_INT)) > - | gpio_get_value(SPITZ_GPIO_SYNC)); > + ret = !gpio_get_value(SPITZ_GPIO_KEY_INT) > + || gpio_get_value(SPITZ_GPIO_SYNC); > return ret; > } >
Joe Perches <joe@perches.com> writes: > On Sat, 2016-07-30 at 13:22 +0200, Robert Jarzmik wrote: ...zip... > $ git grep -w charger_wakeup > arch/arm/mach-pxa/corgi_pm.c: .charger_wakeup = corgi_charger_wakeup, > arch/arm/mach-pxa/sharpsl_pm.c: if (sharpsl_pm.machinfo->charger_wakeup() != 0) > arch/arm/mach-pxa/sharpsl_pm.c: if (sharpsl_pm.machinfo->charger_wakeup()) > arch/arm/mach-pxa/sharpsl_pm.h: unsigned long (*charger_wakeup)(void); > arch/arm/mach-pxa/spitz_pm.c: .charger_wakeup = spitz_charger_wakeup, ...zip... > It may be better to change the charger_wakeup callback return > value from unsigned long to bool and modify the other use in > spitz_pm.c You're most probably right. I'll do that for v3. Cheers.
diff --git a/arch/arm/mach-pxa/corgi_pm.c b/arch/arm/mach-pxa/corgi_pm.c index d9206811be9b..8dc39d602884 100644 --- a/arch/arm/mach-pxa/corgi_pm.c +++ b/arch/arm/mach-pxa/corgi_pm.c @@ -135,11 +135,9 @@ static unsigned long corgi_charger_wakeup(void) { unsigned long ret; - ret = (!gpio_get_value(CORGI_GPIO_AC_IN) << GPIO_bit(CORGI_GPIO_AC_IN)) - | (!gpio_get_value(CORGI_GPIO_KEY_INT) - << GPIO_bit(CORGI_GPIO_KEY_INT)) - | (!gpio_get_value(CORGI_GPIO_WAKEUP) - << GPIO_bit(CORGI_GPIO_WAKEUP)); + ret = !gpio_get_value(CORGI_GPIO_AC_IN) + || !gpio_get_value(CORGI_GPIO_KEY_INT) + || !gpio_get_value(CORGI_GPIO_WAKEUP); return ret; } diff --git a/arch/arm/mach-pxa/spitz_pm.c b/arch/arm/mach-pxa/spitz_pm.c index ea9f9034cb54..dd85869f6f99 100644 --- a/arch/arm/mach-pxa/spitz_pm.c +++ b/arch/arm/mach-pxa/spitz_pm.c @@ -168,9 +168,8 @@ static int spitz_should_wakeup(unsigned int resume_on_alarm) static unsigned long spitz_charger_wakeup(void) { unsigned long ret; - ret = ((!gpio_get_value(SPITZ_GPIO_KEY_INT) - << GPIO_bit(SPITZ_GPIO_KEY_INT)) - | gpio_get_value(SPITZ_GPIO_SYNC)); + ret = !gpio_get_value(SPITZ_GPIO_KEY_INT) + || gpio_get_value(SPITZ_GPIO_SYNC); return ret; }
The commit 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of gpio register") from Oct 17, 2011, leads to the following static checker warning: arch/arm/mach-pxa/spitz_pm.c:172 spitz_charger_wakeup() warn: double left shift '!gpio_get_value(SPITZ_GPIO_KEY_INT) << (1 << ((SPITZ_GPIO_KEY_INT) & 31))' As Dan reported, the value is shifted three times : - once by gpio_get_value(), which returns either 0 or BIT(gpio) - once by the shift operation '<<' - a last time by GPIO_bit(gpio) which is BIT(gpio) Therefore the calculation lead to a chained or operator of : - (1 << gpio) << (1 << gpio) = (2^gpio)^gpio = 2 ^ (gpio * gpio) It is be sheer luck the former statement works, only because each gpio used is strictly smaller than 6, and therefore 2^(gpio^2) never overflows a 32 bits value, and because it is used as a boolean value to check a gpio activation. Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of gpio register") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr> --- Since v1: replaced binary ORs with logical ORs after assembly comparison --- arch/arm/mach-pxa/corgi_pm.c | 8 +++----- arch/arm/mach-pxa/spitz_pm.c | 5 ++--- 2 files changed, 5 insertions(+), 8 deletions(-)