| Message ID | 1450867041-729-2-git-send-email-a.hajda@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
+ Reddy On 12/23/2015 2:37 AM, Andrzej Hajda wrote: > Iterator i declared as unsigned is always non-negative so the > loop will never end. > > The problem has been detected using proposed semantic patch > scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1]. > > [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576 > > Signed-off-by: Andrzej Hajda <a.hajda@samsung.com> > --- > drivers/pinctrl/bcm/pinctrl-nsp-gpio.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c > index 34648f6..ad5b04c 100644 > --- a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c > +++ b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c > @@ -439,7 +439,8 @@ static int nsp_gpio_set_strength(struct nsp_gpio *chip, unsigned gpio, > static int nsp_gpio_get_strength(struct nsp_gpio *chip, unsigned gpio, > u16 *strength) > { > - unsigned int i, offset, shift; > + unsigned int offset, shift; > + int i; > u32 val; > unsigned long flags; > > The fix is a valid fix. And at the same time it exposes other potential issues in the driver. I just found the loop used in _set_strength and _get_strength is inconsistent: In _set_strength: 427 for (i = GPIO_DRV_STRENGTH_BITS; i > 0; i--) { For i to start at GPIO_DRV_STRENGTH_BITS, it seems to be wrong. 428 val = readl(chip->io_ctrl + offset); 429 val &= ~BIT(shift); 430 val |= ((strength >> (i-1)) & 0x1) << shift; 431 writel(val, chip->io_ctrl + offset); 432 offset += 4; 433 } In _get_strength: 451 for (i = (GPIO_DRV_STRENGTH_BITS - 1); i >= 0; i--) { 452 val = readl(chip->io_ctrl + offset) & BIT(shift); 453 val >>= shift; 454 *strength += (val << i); 455 offset += 4; 456 } Reddy, could you please review and comment? Thanks, Ray
On 12/24/2015 4:05 AM, Ray Jui wrote: > + Reddy > > On 12/23/2015 2:37 AM, Andrzej Hajda wrote: >> Iterator i declared as unsigned is always non-negative so the >> loop will never end. >> >> The problem has been detected using proposed semantic patch >> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1]. >> >> [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576 >> >> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com> >> --- >> drivers/pinctrl/bcm/pinctrl-nsp-gpio.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c >> index 34648f6..ad5b04c 100644 >> --- a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c >> +++ b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c >> @@ -439,7 +439,8 @@ static int nsp_gpio_set_strength(struct nsp_gpio *chip, unsigned gpio, >> static int nsp_gpio_get_strength(struct nsp_gpio *chip, unsigned gpio, >> u16 *strength) >> { >> - unsigned int i, offset, shift; >> + unsigned int offset, shift; >> + int i; >> u32 val; >> unsigned long flags; >> >> > The fix is a valid fix. And at the same time it exposes other potential > issues in the driver. I just found the loop used in _set_strength and > _get_strength is inconsistent: > > In _set_strength: > > 427 for (i = GPIO_DRV_STRENGTH_BITS; i > 0; i--) { > > For i to start at GPIO_DRV_STRENGTH_BITS, it seems to be wrong. > > 428 val = readl(chip->io_ctrl + offset); > 429 val &= ~BIT(shift); > 430 val |= ((strength >> (i-1)) & 0x1) << shift; > 431 writel(val, chip->io_ctrl + offset); > 432 offset += 4; > 433 } > > In _get_strength: > > 451 for (i = (GPIO_DRV_STRENGTH_BITS - 1); i >= 0; i--) { > 452 val = readl(chip->io_ctrl + offset) & BIT(shift); > 453 val >>= shift; > 454 *strength += (val << i); > 455 offset += 4; > 456 } > > Reddy, could you please review and comment? Hi Ray, The logic is correct. The drive strength has three bits distributed in three registers. In one case the "-1" is in for loop initialization and the other case it is in the for loop body. The fix looks good. Thanks Dhananjay > Thanks, > > Ray > >
On Wed, Dec 23, 2015 at 11:37 AM, Andrzej Hajda <a.hajda@samsung.com> wrote: > Iterator i declared as unsigned is always non-negative so the > loop will never end. > > The problem has been detected using proposed semantic patch > scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1]. > > [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576 > > Signed-off-by: Andrzej Hajda <a.hajda@samsung.com> I already applied Dan Carpenters fix, somehow it was earlier in my mail flow. Thanks anyways! Yours, Linus Walleij
diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c index 34648f6..ad5b04c 100644 --- a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c +++ b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c @@ -439,7 +439,8 @@ static int nsp_gpio_set_strength(struct nsp_gpio *chip, unsigned gpio, static int nsp_gpio_get_strength(struct nsp_gpio *chip, unsigned gpio, u16 *strength) { - unsigned int i, offset, shift; + unsigned int offset, shift; + int i; u32 val; unsigned long flags;
Iterator i declared as unsigned is always non-negative so the loop will never end. The problem has been detected using proposed semantic patch scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1]. [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576 Signed-off-by: Andrzej Hajda <a.hajda@samsung.com> --- drivers/pinctrl/bcm/pinctrl-nsp-gpio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)