| Message ID | 20210331072111.2945945-1-vkoul@kernel.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | soundwire: qcom: use signed variable for error return | expand |
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 <lkp@intel.com> > Signed-off-by: Vinod Koul <vkoul@kernel.org> > --- > 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 <lkp@intel.com> > > Signed-off-by: Vinod Koul <vkoul@kernel.org> > > --- > > 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 <lkp@intel.com> > Signed-off-by: Vinod Koul <vkoul@kernel.org> > --- > 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 >
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);
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 <lkp@intel.com> Signed-off-by: Vinod Koul <vkoul@kernel.org> --- drivers/soundwire/qcom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.26.3