[PATCH] Input: cyapa - Remove superfluous type check in cyapa_gen5_read_idac_data()

[PATCH] Input: cyapa - Remove superfluous type check in cyapa_gen5_read_idac_data()

[Geert Uytterhoeven]

drivers/input/mouse/cyapa_gen5.c: In function ‘cyapa_gen5_read_idac_data’:
drivers/input/mouse/cyapa_gen5.c:1876: warning: ‘max_element_cnt’ may be used uninitialized in this function
drivers/input/mouse/cyapa_gen5.c:1873: warning: ‘offset’ may be used uninitialized in this function

If *data_size is non-zero, and idac_data_type contains an unknown type,
max_element_cnt and offset will be uninitialized, and the loop will
process non-existing data.

However, this cannot happen (for now), as there's a test for unknown
types at the top of cyapa_gen5_read_idac_data().

As no "if ... else if ..." is used in other places, remove the
superfluous "if" to silence the compiler warning.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
Alternatively, we can pre-initialize max_element_cnt and offset to zero,
and add "if (!max_element_cnt) goto out;" before the loop.

 drivers/input/mouse/cyapa_gen5.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/mouse/cyapa_gen5.c b/drivers/input/mouse/cyapa_gen5.c
index ddf5393a118098fc..88c465b70e9d8776 100644
--- a/drivers/input/mouse/cyapa_gen5.c
+++ b/drivers/input/mouse/cyapa_gen5.c
@@ -1926,7 +1926,7 @@ static int cyapa_gen5_read_idac_data(struct cyapa *cyapa,
 				electrodes_tx = cyapa->electrodes_x;
 			max_element_cnt = ((cyapa->aligned_electrodes_rx + 7) &
 						~7u) * electrodes_tx;
-		} else if (idac_data_type == GEN5_RETRIEVE_SELF_CAP_PWC_DATA) {
+		} else {
 			offset = 2;
 			max_element_cnt = cyapa->electrodes_x +
 						cyapa->electrodes_y;
-- 
1.9.1

RE: [PATCH] Input: cyapa - Remove superfluous type check in cyapa_gen5_read_idac_data()

[Dudley Du]

Thanks for the check.
This fix is verified okay.

Dudley

> -----Original Message-----
> From: Geert Uytterhoeven [mailto:geert@linux-m68k.org]
> Sent: 2015年2月12日 22:16
> To: Dmitry Torokhov; Dudley Du
> Cc: linux-input@vger.kernel.org; linux-kernel@vger.kernel.org; Geert Uytterhoeven
> Subject: [PATCH] Input: cyapa - Remove superfluous type check in
> cyapa_gen5_read_idac_data()
>
> drivers/input/mouse/cyapa_gen5.c: In function ‘cyapa_gen5_read_idac_data’:
> drivers/input/mouse/cyapa_gen5.c:1876: warning: ‘max_element_cnt’ may be
> used uninitialized in this function
> drivers/input/mouse/cyapa_gen5.c:1873: warning: ‘offset’ may be used
> uninitialized in this function
>
> If *data_size is non-zero, and idac_data_type contains an unknown type,
> max_element_cnt and offset will be uninitialized, and the loop will
> process non-existing data.
>
> However, this cannot happen (for now), as there's a test for unknown
> types at the top of cyapa_gen5_read_idac_data().
>
> As no "if ... else if ..." is used in other places, remove the
> superfluous "if" to silence the compiler warning.
>
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> Alternatively, we can pre-initialize max_element_cnt and offset to zero,
> and add "if (!max_element_cnt) goto out;" before the loop.
>
>  drivers/input/mouse/cyapa_gen5.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/input/mouse/cyapa_gen5.c b/drivers/input/mouse/cyapa_gen5.c
> index ddf5393a118098fc..88c465b70e9d8776 100644
> --- a/drivers/input/mouse/cyapa_gen5.c
> +++ b/drivers/input/mouse/cyapa_gen5.c
> @@ -1926,7 +1926,7 @@ static int cyapa_gen5_read_idac_data(struct cyapa
> *cyapa,
>  electrodes_tx = cyapa->electrodes_x;
>  max_element_cnt = ((cyapa->aligned_electrodes_rx + 7) &
>  ~7u) * electrodes_tx;
> -} else if (idac_data_type == GEN5_RETRIEVE_SELF_CAP_PWC_DATA) {
> +} else {
>  offset = 2;
>  max_element_cnt = cyapa->electrodes_x +
>  cyapa->electrodes_y;
> --
> 1.9.1


This message and any attachments may contain Cypress (or its subsidiaries) confidential information. If it has been received in error, please advise the sender and immediately delete this message.

Re: [PATCH] Input: cyapa - Remove superfluous type check in cyapa_gen5_read_idac_data()

[Dmitry Torokhov]

On Mon, Mar 02, 2015 at 04:20:34AM +0000, Dudley Du wrote:
> Thanks for the check.
> This fix is verified okay.

Applied, thank you.

> 
> Dudley
> 
> > -----Original Message-----
> > From: Geert Uytterhoeven [mailto:geert@linux-m68k.org]
> > Sent: 2015年2月12日 22:16
> > To: Dmitry Torokhov; Dudley Du
> > Cc: linux-input@vger.kernel.org; linux-kernel@vger.kernel.org; Geert Uytterhoeven
> > Subject: [PATCH] Input: cyapa - Remove superfluous type check in
> > cyapa_gen5_read_idac_data()
> >
> > drivers/input/mouse/cyapa_gen5.c: In function ‘cyapa_gen5_read_idac_data’:
> > drivers/input/mouse/cyapa_gen5.c:1876: warning: ‘max_element_cnt’ may be
> > used uninitialized in this function
> > drivers/input/mouse/cyapa_gen5.c:1873: warning: ‘offset’ may be used
> > uninitialized in this function
> >
> > If *data_size is non-zero, and idac_data_type contains an unknown type,
> > max_element_cnt and offset will be uninitialized, and the loop will
> > process non-existing data.
> >
> > However, this cannot happen (for now), as there's a test for unknown
> > types at the top of cyapa_gen5_read_idac_data().
> >
> > As no "if ... else if ..." is used in other places, remove the
> > superfluous "if" to silence the compiler warning.
> >
> > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> > ---
> > Alternatively, we can pre-initialize max_element_cnt and offset to zero,
> > and add "if (!max_element_cnt) goto out;" before the loop.
> >
> >  drivers/input/mouse/cyapa_gen5.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/input/mouse/cyapa_gen5.c b/drivers/input/mouse/cyapa_gen5.c
> > index ddf5393a118098fc..88c465b70e9d8776 100644
> > --- a/drivers/input/mouse/cyapa_gen5.c
> > +++ b/drivers/input/mouse/cyapa_gen5.c
> > @@ -1926,7 +1926,7 @@ static int cyapa_gen5_read_idac_data(struct cyapa
> > *cyapa,
> >  electrodes_tx = cyapa->electrodes_x;
> >  max_element_cnt = ((cyapa->aligned_electrodes_rx + 7) &
> >  ~7u) * electrodes_tx;
> > -} else if (idac_data_type == GEN5_RETRIEVE_SELF_CAP_PWC_DATA) {
> > +} else {
> >  offset = 2;
> >  max_element_cnt = cyapa->electrodes_x +
> >  cyapa->electrodes_y;
> > --
> > 1.9.1
> 
> 
> This message and any attachments may contain Cypress (or its subsidiaries) confidential information. If it has been received in error, please advise the sender and immediately delete this message.

-- 
Dmitry