| Message ID | 1469967435-23436-1-git-send-email-robert.jarzmik@free.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, 2016-07-31 at 14:17 +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. > > As the xxx_charger_wakeup() functions are used as a true/false detection > mechanism, take that opportunity to change their prototypes from integer > return value to boolean one. > > Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of > gpio register") > Reported-by: Dan Carpenter <dan.carpenter@oracle.com> > Cc: Joe Perches <joe@perches.com> > Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr> > --- > Since v1: replaced binary ORs with logical ORs after assembly comparison > Since v2: changed charger_wakeup prototype to bool foo() Thanks Robert trivially: > diff --git a/arch/arm/mach-pxa/corgi_pm.c b/arch/arm/mach-pxa/corgi_pm.c [] > @@ -131,15 +131,13 @@ static int corgi_should_wakeup(unsigned int resume_on_alarm) > return is_resume; > } > > -static unsigned long corgi_charger_wakeup(void) > +static bool corgi_charger_wakeup(void) > { > - unsigned long ret; > + bool 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); These might be better without the automatic use of ret return !gpio_get_value(CORGI_GPIO_AC_IN) || !gpio_get_value(CORGI_GPIO_KEY_INT) || !gpio_get_value(CORGI_GPIO_WAKEUP); and > diff --git a/arch/arm/mach-pxa /spitz_pm.c b/arch/arm/mach-pxa/spitz_pm.c [] > @@ -165,12 +165,12 @@ static int spitz_should_wakeup(unsigned int resume_on_alarm) > return is_resume; > } > > -static unsigned long spitz_charger_wakeup(void) > +static bool 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)); > + bool ret; > + > + ret = !gpio_get_value(SPITZ_GPIO_KEY_INT) > + || gpio_get_value(SPITZ_GPIO_SYNC); > return ret; > } return !gpio_get_value(SPITZ_GPIO_KEY_INT) || gpio_get_value(SPITZ_GPIO_SYNC);
Hi Joe, Joe Perches <joe@perches.com> writes: > trivially: >> diff --git a/arch/arm/mach-pxa/corgi_pm.c b/arch/arm/mach-pxa/corgi_pm.c > [] >> @@ -131,15 +131,13 @@ static int corgi_should_wakeup(unsigned int resume_on_alarm) >> return is_resume; >> } >> >> -static unsigned long corgi_charger_wakeup(void) >> +static bool corgi_charger_wakeup(void) >> { >> - unsigned long ret; >> + bool 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); > > These might be better without the automatic use of ret > > return !gpio_get_value(CORGI_GPIO_AC_IN) || > !gpio_get_value(CORGI_GPIO_KEY_INT) || > !gpio_get_value(CORGI_GPIO_WAKEUP); Yeah, I thought about this when I made the patch. I supposed it was written this way so that a printk was easier to add, that's why I didn't change the useless variable. I have no strong opinion about this, so if you think it's worth it I can make the additional change. Cheers. -- Robert
On Mon, 2016-08-01 at 00:04 +0200, Robert Jarzmik wrote: > Joe Perches <joe@perches.com> writes: [] > > These might be better without the automatic use of ret > > > > return !gpio_get_value(CORGI_GPIO_AC_IN) || > > !gpio_get_value(CORGI_GPIO_KEY_INT) || > > !gpio_get_value(CORGI_GPIO_WAKEUP); > Yeah, I thought about this when I made the patch. > > I supposed it was written this way so that a printk was easier to add, that's > why I didn't change the useless variable. > > I have no strong opinion about this, so if you think it's worth it I can make > the additional change. Hi Robert. Your choice. It was one of those, 'oh, bother' type of things but I think it's worth it for readability and consistency. cheers, Joe
diff --git a/arch/arm/mach-pxa/corgi_pm.c b/arch/arm/mach-pxa/corgi_pm.c index d9206811be9b..d935de02b582 100644 --- a/arch/arm/mach-pxa/corgi_pm.c +++ b/arch/arm/mach-pxa/corgi_pm.c @@ -131,15 +131,13 @@ static int corgi_should_wakeup(unsigned int resume_on_alarm) return is_resume; } -static unsigned long corgi_charger_wakeup(void) +static bool corgi_charger_wakeup(void) { - unsigned long ret; + bool 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/sharpsl_pm.c b/arch/arm/mach-pxa/sharpsl_pm.c index b80eab9993c5..249b7bd5fbc4 100644 --- a/arch/arm/mach-pxa/sharpsl_pm.c +++ b/arch/arm/mach-pxa/sharpsl_pm.c @@ -744,7 +744,7 @@ static int sharpsl_off_charge_battery(void) time = RCNR; while (1) { /* Check if any wakeup event had occurred */ - if (sharpsl_pm.machinfo->charger_wakeup() != 0) + if (sharpsl_pm.machinfo->charger_wakeup()) return 0; /* Check for timeout */ if ((RCNR - time) > SHARPSL_WAIT_CO_TIME) diff --git a/arch/arm/mach-pxa/sharpsl_pm.h b/arch/arm/mach-pxa/sharpsl_pm.h index 905be6755f04..fa75b6df8134 100644 --- a/arch/arm/mach-pxa/sharpsl_pm.h +++ b/arch/arm/mach-pxa/sharpsl_pm.h @@ -34,7 +34,7 @@ struct sharpsl_charger_machinfo { #define SHARPSL_STATUS_LOCK 5 #define SHARPSL_STATUS_CHRGFULL 6 #define SHARPSL_STATUS_FATAL 7 - unsigned long (*charger_wakeup)(void); + bool (*charger_wakeup)(void); int (*should_wakeup)(unsigned int resume_on_alarm); void (*backlight_limit)(int); int (*backlight_get_status) (void); diff --git a/arch/arm/mach-pxa/spitz_pm.c b/arch/arm/mach-pxa/spitz_pm.c index ea9f9034cb54..9e2902f32fc2 100644 --- a/arch/arm/mach-pxa/spitz_pm.c +++ b/arch/arm/mach-pxa/spitz_pm.c @@ -165,12 +165,12 @@ static int spitz_should_wakeup(unsigned int resume_on_alarm) return is_resume; } -static unsigned long spitz_charger_wakeup(void) +static bool 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)); + bool ret; + + 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. As the xxx_charger_wakeup() functions are used as a true/false detection mechanism, take that opportunity to change their prototypes from integer return value to boolean one. Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of gpio register") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr> --- Since v1: replaced binary ORs with logical ORs after assembly comparison Since v2: changed charger_wakeup prototype to bool foo() --- arch/arm/mach-pxa/corgi_pm.c | 12 +++++------- arch/arm/mach-pxa/sharpsl_pm.c | 2 +- arch/arm/mach-pxa/sharpsl_pm.h | 2 +- arch/arm/mach-pxa/spitz_pm.c | 10 +++++----- 4 files changed, 12 insertions(+), 14 deletions(-)