Re: [PATCH v2] char: mwave: smapi: Fix signedness of SmapiOK variable

[Purva Yeshi]

On 17/04/25 15:08, Greg KH wrote:
> On Thu, Apr 17, 2025 at 02:40:18PM +0530, Purva Yeshi wrote:
> > Smatch warning:
> > drivers/char/mwave/smapi.c:69 smapi_request() warn:
> > assigning (-5) to unsigned variable 'usSmapiOK'
> >
> > Fix Smatch warning caused by assigning -EIO to an unsigned short.
> >
> > Smatch detected a warning due to assigning -EIO (a negative value) to an
> > unsigned short variable, causing a type mismatch and potential issues.
> >
> > In v1, the type was changed to short, which resolved the warning, but
> > retained the misleading "us" prefix in the variable name.
> >
> > In v2, update the type to s16 and rename the variable to SmapiOK,
> > removing the "us" (unsigned short) prefix as per Greg KH suggestion.
> >
> > This change ensures type correctness, avoids confusion, and improves
> > overall code readability.
> >
> > Signed-off-by: Purva Yeshi <purvayeshi550@xxxxxxxxx>
> > ---
> > V1 - https://lore.kernel.org/all/20250409211929.213360-1-purvayeshi550@xxxxxxxxx/
> > V2 - Use s16 type and rename variable to remove misleading "us" prefix.
> >
> >   drivers/char/mwave/smapi.c | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/char/mwave/smapi.c b/drivers/char/mwave/smapi.c
> > index f8d79d393b69..65bc7e1ea6cf 100644
> > --- a/drivers/char/mwave/smapi.c
> > +++ b/drivers/char/mwave/smapi.c
> > @@ -66,7 +66,7 @@ static int smapi_request(unsigned short inBX, unsigned short inCX,
> >   	unsigned short myoutDX = 5, *pmyoutDX = &myoutDX;
> >   	unsigned short myoutDI = 6, *pmyoutDI = &myoutDI;
> >   	unsigned short myoutSI = 7, *pmyoutSI = &myoutSI;
> > -	unsigned short usSmapiOK = -EIO, *pusSmapiOK = &usSmapiOK;
> > +	s16 SmapiOK = -EIO, *pSmapiOK = &SmapiOK;
>
> Do you think that "SmapiOK" is a valid kernel variable name?  Doesn't
> look ok to me, what does checkpatch.pl say?  :)
>
> thanks,
>
> greg k-h

Hi Greg,

Thank you for the feedback.

I ran checkpatch.pl on the patch, and it reports 0 errors and 0 
warnings, so the variable name "SmapiOK" is valid in this context.

Regarding the "usSmapiOK" variable, it was used only within the smapi.c 
file. Therefore, I have renamed it consistently throughout the file to 
avoid the misleading "us" prefix.

Let me know if you have any further suggestions.

Best regards,
Purva