[PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Gustavo A. R. Silva]

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 1397962 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/iio/accel/cros_ec_accel_legacy.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
index 063e89e..d609654 100644
--- a/drivers/iio/accel/cros_ec_accel_legacy.c
+++ b/drivers/iio/accel/cros_ec_accel_legacy.c
@@ -385,8 +385,10 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
 		switch (i) {
 		case X:
 			ec_accel_channels[X].scan_index = Y;
+			/* fall through */
 		case Y:
 			ec_accel_channels[Y].scan_index = X;
+			/* fall through */
 		case Z:
 			ec_accel_channels[Z].scan_index = Z;
 		}
-- 
2.7.4

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Jonathan Cameron]

On Mon, 8 Oct 2018 19:23:32 +0200
"Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:

> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
> where we are expecting to fall through.
> 
> Addresses-Coverity-ID: 1397962 ("Missing break in switch")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Hi,

I'll be honest I'm lost on what the intent of this code actually is...

Gwendal - why do we have a loop with this odd switch statement
in it.  Superficially I think we might as well drop the switch
and pull those assignments out of the loop.   However, perhaps
I'm missing something!

Thanks,

Jonathan

> ---
>  drivers/iio/accel/cros_ec_accel_legacy.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
> index 063e89e..d609654 100644
> --- a/drivers/iio/accel/cros_ec_accel_legacy.c
> +++ b/drivers/iio/accel/cros_ec_accel_legacy.c
> @@ -385,8 +385,10 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
>  		switch (i) {
>  		case X:
>  			ec_accel_channels[X].scan_index = Y;
> +			/* fall through */
>  		case Y:
>  			ec_accel_channels[Y].scan_index = X;
> +			/* fall through */
>  		case Z:
>  			ec_accel_channels[Z].scan_index = Z;
>  		}

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Gustavo A. R. Silva]

Hi guys,

I was about to submit this patch again, then I realized I had
sent it before.

So, this is a friendly ping.

Thanks
--
Gustavo

On 10/8/18 3:30 PM, Jonathan Cameron wrote:
> On Mon, 8 Oct 2018 19:23:32 +0200
> "Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:
> 
>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>> where we are expecting to fall through.
>>
>> Addresses-Coverity-ID: 1397962 ("Missing break in switch")
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> Hi,
> 
> I'll be honest I'm lost on what the intent of this code actually is...
> 
> Gwendal - why do we have a loop with this odd switch statement
> in it.  Superficially I think we might as well drop the switch
> and pull those assignments out of the loop.   However, perhaps
> I'm missing something!
> 
> Thanks,
> 
> Jonathan
> 
>> ---
>>  drivers/iio/accel/cros_ec_accel_legacy.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
>> index 063e89e..d609654 100644
>> --- a/drivers/iio/accel/cros_ec_accel_legacy.c
>> +++ b/drivers/iio/accel/cros_ec_accel_legacy.c
>> @@ -385,8 +385,10 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
>>  		switch (i) {
>>  		case X:
>>  			ec_accel_channels[X].scan_index = Y;
>> +			/* fall through */
>>  		case Y:
>>  			ec_accel_channels[Y].scan_index = X;
>> +			/* fall through */
>>  		case Z:
>>  			ec_accel_channels[Z].scan_index = Z;
>>  		}
> 

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Kees Cook]

On Mon, Oct 8, 2018 at 10:24 AM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
>
> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
> where we are expecting to fall through.
>
> Addresses-Coverity-ID: 1397962 ("Missing break in switch")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/iio/accel/cros_ec_accel_legacy.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
> index 063e89e..d609654 100644
> --- a/drivers/iio/accel/cros_ec_accel_legacy.c
> +++ b/drivers/iio/accel/cros_ec_accel_legacy.c
> @@ -385,8 +385,10 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
>                 switch (i) {
>                 case X:
>                         ec_accel_channels[X].scan_index = Y;
> +                       /* fall through */
>                 case Y:
>                         ec_accel_channels[Y].scan_index = X;
> +                       /* fall through */
>                 case Z:
>                         ec_accel_channels[Z].scan_index = Z;
>                 }

Shouldn't these actually be "break;"s ? It seems like the loop is
stepping through X, Y, and Z. The _result_ is accidentally the same:

X: set X, Y, and Z
Y: set Y and Z
Z: set Z

result: X, Y, and Z are set correctly. But the code is technically wrong.


-- 
Kees Cook

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Jonathan Cameron]

On Wed, 20 Feb 2019 10:20:39 -0800
Kees Cook <keescook@chromium.org> wrote:

> On Mon, Oct 8, 2018 at 10:24 AM Gustavo A. R. Silva
> <gustavo@embeddedor.com> wrote:
> >
> > In preparation to enabling -Wimplicit-fallthrough, mark switch cases
> > where we are expecting to fall through.
> >
> > Addresses-Coverity-ID: 1397962 ("Missing break in switch")
> > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> > ---
> >  drivers/iio/accel/cros_ec_accel_legacy.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
> > index 063e89e..d609654 100644
> > --- a/drivers/iio/accel/cros_ec_accel_legacy.c
> > +++ b/drivers/iio/accel/cros_ec_accel_legacy.c
> > @@ -385,8 +385,10 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
> >                 switch (i) {
> >                 case X:
> >                         ec_accel_channels[X].scan_index = Y;
> > +                       /* fall through */
> >                 case Y:
> >                         ec_accel_channels[Y].scan_index = X;
> > +                       /* fall through */
> >                 case Z:
> >                         ec_accel_channels[Z].scan_index = Z;
> >                 }  
> 
> Shouldn't these actually be "break;"s ? It seems like the loop is
> stepping through X, Y, and Z. The _result_ is accidentally the same:
> 
> X: set X, Y, and Z
> Y: set Y and Z
> Z: set Z
> 
> result: X, Y, and Z are set correctly. But the code is technically wrong.
> 

Agreed, it's 'novel'.  Waiting for Gwendal or someone else to come
back and check it wasn't meant to be doing something else.

Jonathan

> 

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Gustavo A. R. Silva]

On 2/20/19 12:34 PM, Jonathan Cameron wrote:
> On Wed, 20 Feb 2019 10:20:39 -0800
> Kees Cook <keescook@chromium.org> wrote:
> 
>> On Mon, Oct 8, 2018 at 10:24 AM Gustavo A. R. Silva
>> <gustavo@embeddedor.com> wrote:
>>>
>>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>>> where we are expecting to fall through.
>>>
>>> Addresses-Coverity-ID: 1397962 ("Missing break in switch")
>>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>>> ---
>>>  drivers/iio/accel/cros_ec_accel_legacy.c | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
>>> index 063e89e..d609654 100644
>>> --- a/drivers/iio/accel/cros_ec_accel_legacy.c
>>> +++ b/drivers/iio/accel/cros_ec_accel_legacy.c
>>> @@ -385,8 +385,10 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
>>>                 switch (i) {
>>>                 case X:
>>>                         ec_accel_channels[X].scan_index = Y;
>>> +                       /* fall through */
>>>                 case Y:
>>>                         ec_accel_channels[Y].scan_index = X;
>>> +                       /* fall through */
>>>                 case Z:
>>>                         ec_accel_channels[Z].scan_index = Z;
>>>                 }  
>>
>> Shouldn't these actually be "break;"s ? It seems like the loop is
>> stepping through X, Y, and Z. The _result_ is accidentally the same:
>>
>> X: set X, Y, and Z
>> Y: set Y and Z
>> Z: set Z
>>
>> result: X, Y, and Z are set correctly. But the code is technically wrong.
>>

Yeah. Actually, we can even take the switch and for out of the equation,
and the code can be rewritten as follows:

ec_accel_channels[X].scan_index = Y;
ec_accel_channels[Y].scan_index = X;
ec_accel_channels[Z].scan_index = Z;

if (state->sensor_num == MOTIONSENSE_LOC_LID)
	state->sign[X] = state->sign[Z] = -1;
else
	state->sign[X] = state->sign[Y] = state->sign[Z] = 1;

> 
> Agreed, it's 'novel'.  Waiting for Gwendal or someone else to come
> back and check it wasn't meant to be doing something else.
> 

We've been waiting 5 months for Gwendal. :/

Thanks
--
Gustavo

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Kees Cook]

On Wed, Feb 20, 2019 at 10:47 AM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
> Yeah. Actually, we can even take the switch and for out of the equation,
> and the code can be rewritten as follows:
>
> ec_accel_channels[X].scan_index = Y;
> ec_accel_channels[Y].scan_index = X;
> ec_accel_channels[Z].scan_index = Z;
>
> if (state->sensor_num == MOTIONSENSE_LOC_LID)
>         state->sign[X] = state->sign[Z] = -1;
> else
>         state->sign[X] = state->sign[Y] = state->sign[Z] = 1;

Actually, should be an unconditional "state->sign[Y] = 1", but
otherwise, yes. Can you send that patch?


> > Agreed, it's 'novel'.  Waiting for Gwendal or someone else to come
> > back and check it wasn't meant to be doing something else.
>
> We've been waiting 5 months for Gwendal. :/

I've looked at this enough. I'm happy to Ack it, if that helps. :)

-- 
Kees Cook

Re: [PATCH] iio: cros_ec_accel_legacy: Mark expected switch fall-throughs

[Gustavo A. R. Silva]

On 2/20/19 7:23 PM, Kees Cook wrote:
> On Wed, Feb 20, 2019 at 10:47 AM Gustavo A. R. Silva
> <gustavo@embeddedor.com> wrote:
>> Yeah. Actually, we can even take the switch and for out of the equation,
>> and the code can be rewritten as follows:
>>
>> ec_accel_channels[X].scan_index = Y;
>> ec_accel_channels[Y].scan_index = X;
>> ec_accel_channels[Z].scan_index = Z;
>>
>> if (state->sensor_num == MOTIONSENSE_LOC_LID)
>>         state->sign[X] = state->sign[Z] = -1;
>> else
>>         state->sign[X] = state->sign[Y] = state->sign[Z] = 1;
> 
> Actually, should be an unconditional "state->sign[Y] = 1", but

You're right. Team work!

> otherwise, yes. Can you send that patch?
> 

Sure thing.

> 
>>> Agreed, it's 'novel'.  Waiting for Gwendal or someone else to come
>>> back and check it wasn't meant to be doing something else.
>>
>> We've been waiting 5 months for Gwendal. :/
> 
> I've looked at this enough. I'm happy to Ack it, if that helps. :)
> 

Awesome. :)

Thanks
--
Gustavo