| Message ID | 20231229121504.3479594-1-himanshu.bhavani@siliconsignals.io |
|---|---|
| State | Superseded |
| Headers | show |
| Series | media: venus: use div64_u64() instead of do_div() | expand |
On 12/29/2023 5:45 PM, Himanshu Bhavani wrote: > do_div() does a 64-by-32 division. > When the divisor is u64, do_div() truncates it to 32 bits, this means it > can test non-zero and be truncated to zero for division. > > fix do_div.cocci warning: > do_div() does a 64-by-32 division, please consider using div64_u64 instead. > > Signed-off-by: Himanshu Bhavani <himanshu.bhavani@siliconsignals.io> > > diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c > index 44b13696cf82..81853eb2993a 100644 > --- a/drivers/media/platform/qcom/venus/venc.c > +++ b/drivers/media/platform/qcom/venus/venc.c > @@ -409,13 +409,13 @@ static int venc_s_parm(struct file *file, void *fh, struct v4l2_streamparm *a) > out->capability = V4L2_CAP_TIMEPERFRAME; > > us_per_frame = timeperframe->numerator * (u64)USEC_PER_SEC; > - do_div(us_per_frame, timeperframe->denominator); > + div64_u64(us_per_frame, timeperframe->denominator); I think, this should be like below: us_per_frame = div64_u64(us_per_frame, timeperframe->denominator); because do_div does the in-place division while div64_u64 doesn't. so final value of us_per_frame won't be correct with this change. > > if (!us_per_frame) > return -EINVAL; > > fps = (u64)USEC_PER_SEC; > - do_div(fps, us_per_frame); > + div64_u64(fps, us_per_frame); ditto.. fps = div64_u64(fps, us_per_frame); > > inst->timeperframe = *timeperframe; > inst->fps = fps; Thanks, Dikshita
On Fri, 29 Dec 2023 at 14:16, Himanshu Bhavani <himanshu.bhavani@siliconsignals.io> wrote: > > do_div() does a 64-by-32 division. > When the divisor is u64, do_div() truncates it to 32 bits, this means it > can test non-zero and be truncated to zero for division. > > fix do_div.cocci warning: > do_div() does a 64-by-32 division, please consider using div64_u64 instead. > > Signed-off-by: Himanshu Bhavani <himanshu.bhavani@siliconsignals.io> > > diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c > index 44b13696cf82..81853eb2993a 100644 > --- a/drivers/media/platform/qcom/venus/venc.c > +++ b/drivers/media/platform/qcom/venus/venc.c > @@ -409,13 +409,13 @@ static int venc_s_parm(struct file *file, void *fh, struct v4l2_streamparm *a) > out->capability = V4L2_CAP_TIMEPERFRAME; > > us_per_frame = timeperframe->numerator * (u64)USEC_PER_SEC; > - do_div(us_per_frame, timeperframe->denominator); > + div64_u64(us_per_frame, timeperframe->denominator); NAK! This is completely incorrect. do_div() is a macro and it changes the first argument. div64_u64 is a function, which returns the result instead of changing the first argument. Please consider checking the code before sending a patch. > > if (!us_per_frame) > return -EINVAL; > > fps = (u64)USEC_PER_SEC; > - do_div(fps, us_per_frame); > + div64_u64(fps, us_per_frame); > > inst->timeperframe = *timeperframe; > inst->fps = fps; > -- > 2.25.1 > >
diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c index 44b13696cf82..81853eb2993a 100644 --- a/drivers/media/platform/qcom/venus/venc.c +++ b/drivers/media/platform/qcom/venus/venc.c @@ -409,13 +409,13 @@ static int venc_s_parm(struct file *file, void *fh, struct v4l2_streamparm *a) out->capability = V4L2_CAP_TIMEPERFRAME; us_per_frame = timeperframe->numerator * (u64)USEC_PER_SEC; - do_div(us_per_frame, timeperframe->denominator); + div64_u64(us_per_frame, timeperframe->denominator); if (!us_per_frame) return -EINVAL; fps = (u64)USEC_PER_SEC; - do_div(fps, us_per_frame); + div64_u64(fps, us_per_frame); inst->timeperframe = *timeperframe; inst->fps = fps;
do_div() does a 64-by-32 division. When the divisor is u64, do_div() truncates it to 32 bits, this means it can test non-zero and be truncated to zero for division. fix do_div.cocci warning: do_div() does a 64-by-32 division, please consider using div64_u64 instead. Signed-off-by: Himanshu Bhavani <himanshu.bhavani@siliconsignals.io>