| Message ID | 1536404256-25189-1-git-send-email-zhongjiang@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iio: remove unnecessary condition judgment in am2315_trigger_handler | expand |
On Sat, Sep 08, 2018 at 06:57:36PM +0800, zhong jiang wrote: > The iterator in for_each_set_bit is never null, therefore, remove > the redundant conditional judgment. > > Signed-off-by: zhong jiang <zhongjiang@huawei.com> > --- > drivers/iio/humidity/am2315.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c > index 7d8669d..dc12e37 100644 > --- a/drivers/iio/humidity/am2315.c > +++ b/drivers/iio/humidity/am2315.c > @@ -176,8 +176,7 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p) > i = 0; > for_each_set_bit(bit, indio_dev->active_scan_mask, > indio_dev->masklength) { > - data->buffer[i] = (bit ? sensor_data.temp_data : > - sensor_data.hum_data); > + data->buffer[i] = sensor_data.temp_data; No, this seems wrong! We have buffer support to either take both readings(temp & humid) simultaneously, or only single channel using specified scan mask. Patch title should be: "iio: humidity: am2315: .... .. " Thanks
On Sat, 8 Sep 2018 17:59:13 +0530 Himanshu Jha <himanshujha199640@gmail.com> wrote: > On Sat, Sep 08, 2018 at 06:57:36PM +0800, zhong jiang wrote: > > The iterator in for_each_set_bit is never null, therefore, remove > > the redundant conditional judgment. > > > > Signed-off-by: zhong jiang <zhongjiang@huawei.com> > > --- > > drivers/iio/humidity/am2315.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c > > index 7d8669d..dc12e37 100644 > > --- a/drivers/iio/humidity/am2315.c > > +++ b/drivers/iio/humidity/am2315.c > > @@ -176,8 +176,7 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p) > > i = 0; > > for_each_set_bit(bit, indio_dev->active_scan_mask, > > indio_dev->masklength) { > > - data->buffer[i] = (bit ? sensor_data.temp_data : > > - sensor_data.hum_data); > > + data->buffer[i] = sensor_data.temp_data; > > No, this seems wrong! > > We have buffer support to either take both readings(temp & humid) > simultaneously, or only single channel using specified scan mask. Key think is that bit most definitely can be 0 if the 0th bit is set. This isn't a null check at all. I'm curious, was this a by inspection case or did some script throw this one up? Thanks, Jonathan > > Patch title should be: > > "iio: humidity: am2315: .... .. " > > > Thanks
On 2018/9/8 22:17, Jonathan Cameron wrote: > On Sat, 8 Sep 2018 17:59:13 +0530 > Himanshu Jha <himanshujha199640@gmail.com> wrote: > >> On Sat, Sep 08, 2018 at 06:57:36PM +0800, zhong jiang wrote: >>> The iterator in for_each_set_bit is never null, therefore, remove >>> the redundant conditional judgment. >>> >>> Signed-off-by: zhong jiang <zhongjiang@huawei.com> >>> --- >>> drivers/iio/humidity/am2315.c | 3 +-- >>> 1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c >>> index 7d8669d..dc12e37 100644 >>> --- a/drivers/iio/humidity/am2315.c >>> +++ b/drivers/iio/humidity/am2315.c >>> @@ -176,8 +176,7 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p) >>> i = 0; >>> for_each_set_bit(bit, indio_dev->active_scan_mask, >>> indio_dev->masklength) { >>> - data->buffer[i] = (bit ? sensor_data.temp_data : >>> - sensor_data.hum_data); >>> + data->buffer[i] = sensor_data.temp_data; >> No, this seems wrong! >> >> We have buffer support to either take both readings(temp & humid) >> simultaneously, or only single channel using specified scan mask. > Key think is that bit most definitely can be 0 if the 0th bit is set. > This isn't a null check at all. > > I'm curious, was this a by inspection case or did some script throw > this one up? Hi, Jonathan bit is a iterator that find the non-zero bit in indio_dev->active_scan_mask. if all bit is zero , it should return the masklength. Yep. I find the issue with the help of Coccinelle. Thanks zhong jiang > Thanks, > > Jonathan > >> Patch title should be: >> >> "iio: humidity: am2315: .... .. " >> >> >> Thanks > > . >
On 9/8/2018 7:17 AM, Jonathan Cameron wrote: > On Sat, 8 Sep 2018 17:59:13 +0530 > Himanshu Jha <himanshujha199640@gmail.com> wrote: > >> On Sat, Sep 08, 2018 at 06:57:36PM +0800, zhong jiang wrote: >>> The iterator in for_each_set_bit is never null, therefore, remove >>> the redundant conditional judgment. >>> >>> Signed-off-by: zhong jiang <zhongjiang@huawei.com> >>> --- >>> drivers/iio/humidity/am2315.c | 3 +-- >>> 1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c >>> index 7d8669d..dc12e37 100644 >>> --- a/drivers/iio/humidity/am2315.c >>> +++ b/drivers/iio/humidity/am2315.c >>> @@ -176,8 +176,7 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p) >>> i = 0; >>> for_each_set_bit(bit, indio_dev->active_scan_mask, >>> indio_dev->masklength) { >>> - data->buffer[i] = (bit ? sensor_data.temp_data : >>> - sensor_data.hum_data); >>> + data->buffer[i] = sensor_data.temp_data; >> >> No, this seems wrong! >> >> We have buffer support to either take both readings(temp & humid) >> simultaneously, or only single channel using specified scan mask. > > Key think is that bit most definitely can be 0 if the 0th bit is set. > This isn't a null check at all. > > I'm curious, was this a by inspection case or did some script throw > this one up? Firstly, +1 on the patch in this thread being an incorrect change. While inspecting the surrounding code, I noticed that there's a bit of questionable code in this area. I believe this whole chunk: if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) { data->buffer[0] = sensor_data.hum_data; data->buffer[1] = sensor_data.temp_data; } else { i = 0; for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) { data->buffer[i] = (bit ? sensor_data.temp_data : sensor_data.hum_data); i++; } } could be reduced to this: for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) data->buffer[bit] = (bit ? sensor_data.temp_data : sensor_data.hum_data); The if/else structure seems like an unnecessary optimization. Thoughts?
On 2018/9/10 21:49, zhong jiang wrote: > On 2018/9/8 22:17, Jonathan Cameron wrote: >> On Sat, 8 Sep 2018 17:59:13 +0530 >> Himanshu Jha <himanshujha199640@gmail.com> wrote: >> >>> On Sat, Sep 08, 2018 at 06:57:36PM +0800, zhong jiang wrote: >>>> The iterator in for_each_set_bit is never null, therefore, remove >>>> the redundant conditional judgment. >>>> >>>> Signed-off-by: zhong jiang <zhongjiang@huawei.com> >>>> --- >>>> drivers/iio/humidity/am2315.c | 3 +-- >>>> 1 file changed, 1 insertion(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c >>>> index 7d8669d..dc12e37 100644 >>>> --- a/drivers/iio/humidity/am2315.c >>>> +++ b/drivers/iio/humidity/am2315.c >>>> @@ -176,8 +176,7 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p) >>>> i = 0; >>>> for_each_set_bit(bit, indio_dev->active_scan_mask, >>>> indio_dev->masklength) { >>>> - data->buffer[i] = (bit ? sensor_data.temp_data : >>>> - sensor_data.hum_data); >>>> + data->buffer[i] = sensor_data.temp_data; >>> No, this seems wrong! >>> >>> We have buffer support to either take both readings(temp & humid) >>> simultaneously, or only single channel using specified scan mask. >> Key think is that bit most definitely can be 0 if the 0th bit is set. >> This isn't a null check at all. >> >> I'm curious, was this a by inspection case or did some script throw >> this one up? > Hi, Jonathan > > bit is a iterator that find the non-zero bit in indio_dev->active_scan_mask. if all bit is > zero , it should return the masklength. That's my stupid fault. The patch is totally wrong.:-( Thanks, zhong jiang > Yep. I find the issue with the help of Coccinelle. > > Thanks > zhong jiang >> Thanks, >> >> Jonathan >> >>> Patch title should be: >>> >>> "iio: humidity: am2315: .... .. " >>> >>> >>> Thanks >> . >> > > > . >
diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c index 7d8669d..dc12e37 100644 --- a/drivers/iio/humidity/am2315.c +++ b/drivers/iio/humidity/am2315.c @@ -176,8 +176,7 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p) i = 0; for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) { - data->buffer[i] = (bit ? sensor_data.temp_data : - sensor_data.hum_data); + data->buffer[i] = sensor_data.temp_data; i++; } }
The iterator in for_each_set_bit is never null, therefore, remove the redundant conditional judgment. Signed-off-by: zhong jiang <zhongjiang@huawei.com> --- drivers/iio/humidity/am2315.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)