We get warning for using a unsigned variable being compared to less than
zero. The comparison is correct as it checks for errors from previous
call to qcom_swrm_get_alert_slave_dev_num(), so we should use a signed
variable instead.
drivers/soundwire/qcom.c: qcom_swrm_irq_handler() warn: impossible
condition '(devnum < 0) => (0-255 < 0)'
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Vinod Koul <[email protected]>
---
drivers/soundwire/qcom.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
index b08ecb9b418c..55ed133c6704 100644
--- a/drivers/soundwire/qcom.c
+++ b/drivers/soundwire/qcom.c
@@ -428,7 +428,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
struct qcom_swrm_ctrl *swrm = dev_id;
u32 value, intr_sts, intr_sts_masked, slave_status;
u32 i;
- u8 devnum = 0;
+ s8 devnum = 0;
int ret = IRQ_HANDLED;
swrm->reg_read(swrm, SWRM_INTERRUPT_STATUS, &intr_sts);
--
2.26.3
On 3/31/21 2:21 AM, Vinod Koul wrote:
> We get warning for using a unsigned variable being compared to less than
> zero. The comparison is correct as it checks for errors from previous
> call to qcom_swrm_get_alert_slave_dev_num(), so we should use a signed
> variable instead.
>
> drivers/soundwire/qcom.c: qcom_swrm_irq_handler() warn: impossible
> condition '(devnum < 0) => (0-255 < 0)'
>
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Vinod Koul <[email protected]>
> ---
> drivers/soundwire/qcom.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> index b08ecb9b418c..55ed133c6704 100644
> --- a/drivers/soundwire/qcom.c
> +++ b/drivers/soundwire/qcom.c
> @@ -428,7 +428,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
> struct qcom_swrm_ctrl *swrm = dev_id;
> u32 value, intr_sts, intr_sts_masked, slave_status;
> u32 i;
> - u8 devnum = 0;
> + s8 devnum = 0;
it's not great to store negative error codes with s8. That works in this
specific case because the function only returns -EINVAL.
We actually have zero occurrences of s8 in the drivers/soundwire/ code.
> int ret = IRQ_HANDLED;
>
> swrm->reg_read(swrm, SWRM_INTERRUPT_STATUS, &intr_sts);
>
On 31-03-21, 09:41, Pierre-Louis Bossart wrote:
>
>
> On 3/31/21 2:21 AM, Vinod Koul wrote:
> > We get warning for using a unsigned variable being compared to less than
> > zero. The comparison is correct as it checks for errors from previous
> > call to qcom_swrm_get_alert_slave_dev_num(), so we should use a signed
> > variable instead.
> >
> > drivers/soundwire/qcom.c: qcom_swrm_irq_handler() warn: impossible
> > condition '(devnum < 0) => (0-255 < 0)'
> >
> > Reported-by: kernel test robot <[email protected]>
> > Signed-off-by: Vinod Koul <[email protected]>
> > ---
> > drivers/soundwire/qcom.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> > index b08ecb9b418c..55ed133c6704 100644
> > --- a/drivers/soundwire/qcom.c
> > +++ b/drivers/soundwire/qcom.c
> > @@ -428,7 +428,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
> > struct qcom_swrm_ctrl *swrm = dev_id;
> > u32 value, intr_sts, intr_sts_masked, slave_status;
> > u32 i;
> > - u8 devnum = 0;
> > + s8 devnum = 0;
>
> it's not great to store negative error codes with s8. That works in this
> specific case because the function only returns -EINVAL.
Yeah I did check EINVAL was the case which would work but in general I
agree that makes sense, I discussed with Srini on IRC and looks like I
havent posted v2, should hit the pipes shortly
--
~Vinod
On Wed 31 Mar 02:21 CDT 2021, Vinod Koul wrote:
> We get warning for using a unsigned variable being compared to less than
> zero. The comparison is correct as it checks for errors from previous
> call to qcom_swrm_get_alert_slave_dev_num(), so we should use a signed
> variable instead.
>
> drivers/soundwire/qcom.c: qcom_swrm_irq_handler() warn: impossible
> condition '(devnum < 0) => (0-255 < 0)'
>
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Vinod Koul <[email protected]>
> ---
> drivers/soundwire/qcom.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> index b08ecb9b418c..55ed133c6704 100644
> --- a/drivers/soundwire/qcom.c
> +++ b/drivers/soundwire/qcom.c
> @@ -428,7 +428,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
> struct qcom_swrm_ctrl *swrm = dev_id;
> u32 value, intr_sts, intr_sts_masked, slave_status;
> u32 i;
> - u8 devnum = 0;
> + s8 devnum = 0;
At least in today's linux-next qcom_swrm_get_alert_slave_dev_num()
returns an int and the code only checks to see if this is negative. So
it seems like making this a full int ensures there's no truncation etc.
And at least as written today there's no need to initialize the
variable.
Regards,
Bjorn
> int ret = IRQ_HANDLED;
>
> swrm->reg_read(swrm, SWRM_INTERRUPT_STATUS, &intr_sts);
> --
> 2.26.3
>