2017-06-15 02:36:51

by Gustavo A. R. Silva

Subject: [PATCH] USB: gtco: remove unnecessary variable assignments

Remove unnecessary variable assignments.
Variable _val_ is overwritten before the value stored in it can be used.

Addresses-Coverity-ID: 1397695
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/input/tablet/gtco.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
index b796e89..d9de13c 100644
--- a/drivers/input/tablet/gtco.c
+++ b/drivers/input/tablet/gtco.c
@@ -652,8 +652,6 @@ static void gtco_urb_callback(struct urb *urbinfo)
switch (device->buffer[0]) {
case 5:
/* Pressure is 9 bits */
- val = ((u16)(device->buffer[8]) << 1);
- val |= (u16)(device->buffer[7] >> 7);
input_report_abs(inputdev, ABS_PRESSURE,
device->buffer[8]);

--
2.5.0

2017-06-15 05:00:53

by Joe Perches

Subject: Re: [PATCH] USB: gtco: remove unnecessary variable assignments

On Wed, 2017-06-14 at 20:50 -0500, Gustavo A. R. Silva wrote:
> Remove unnecessary variable assignments.
> Variable _val_ is overwritten before the value stored in it can be used.
>
> Addresses-Coverity-ID: 1397695
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> drivers/input/tablet/gtco.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
> index b796e89..d9de13c 100644
> --- a/drivers/input/tablet/gtco.c
> +++ b/drivers/input/tablet/gtco.c
> @@ -652,8 +652,6 @@ static void gtco_urb_callback(struct urb *urbinfo)
> switch (device->buffer[0]) {
> case 5:
> /* Pressure is 9 bits */
> - val = ((u16)(device->buffer[8]) << 1);
> - val |= (u16)(device->buffer[7] >> 7);
> input_report_abs(inputdev, ABS_PRESSURE,
> device->buffer[8]);

Perhaps more likely to be

input_report_abs(inputdev, ABS_PRESSURE, val);

2017-06-15 20:02:39

by Ulrik De Bie

Subject: Re: [PATCH] USB: gtco: remove unnecessary variable assignments

Hi Joe, Gustavo,

On Wed, Jun 14, 2017 at 10:00:48PM -0700, Joe Perches wrote:
> On Wed, 2017-06-14 at 20:50 -0500, Gustavo A. R. Silva wrote:
> > Remove unnecessary variable assignments.
> > Variable _val_ is overwritten before the value stored in it can be used.
> >
> > Addresses-Coverity-ID: 1397695
> > Signed-off-by: Gustavo A. R. Silva <[email protected]>
> > ---
> > drivers/input/tablet/gtco.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
> > index b796e89..d9de13c 100644
> > --- a/drivers/input/tablet/gtco.c
> > +++ b/drivers/input/tablet/gtco.c
> > @@ -652,8 +652,6 @@ static void gtco_urb_callback(struct urb *urbinfo)
> > switch (device->buffer[0]) {
> > case 5:
> > /* Pressure is 9 bits */
> > - val = ((u16)(device->buffer[8]) << 1);
> > - val |= (u16)(device->buffer[7] >> 7);
> > input_report_abs(inputdev, ABS_PRESSURE,
> > device->buffer[8]);
>
> Perhaps more likely to be
>
> input_report_abs(inputdev, ABS_PRESSURE, val);

Probably that was the original intention but changing it that way now
would give a shift of factor 2 to userspace.

But if the 2 lines are deleted, I would update the comment above it so it
is clear the lowest significant bit in buffer[7] is not included in the
report call.

Kind regards,
Ulrik