Re: [PATCH 4/4] video: Remove stack VLA usage

[Gustavo A. R. Silva]

I sent a patch for this six hours ago:

https://patchwork.kernel.org/patch/10268591/

--
Gustavo

On 03/09/2018 12:11 AM, Tycho Andersen wrote:
> On Thu, Mar 08, 2018 at 10:01:07PM -0800, Joe Perches wrote:
> > On Fri, 2018-03-09 at 16:50 +1100, Tobin C. Harding wrote:
> > > The kernel would like to have all stack VLA usage removed[1].  The
> > > arrays are fixed here (declared with a const variable) but they appear
> > > like VLAs to the compiler.  We can use a pre-processor define to fix the
> > > warning.
> > []
> > > diff --git a/drivers/video/fbdev/via/via_aux_sii164.c b/drivers/video/fbdev/via/via_aux_sii164.c
> > []
> > > @@ -27,6 +27,9 @@
> > >   
> > >   static const char *name = "SiI 164 PanelLink Transmitter";
> > >   
> > > +/* check vendor id and device id */
> > > +const u8 id[] = {0x01, 0x00, 0x06, 0x00};
> >
> > It seems id is now global in multiple places.
> > Perhaps these should be static.
>
> Does it even need to be global? Why not just get rid of the indirection and use
> ARRAY_SIZE where we mean it? This seems to work for me,
>
> diff --git a/drivers/video/fbdev/via/via_aux_sii164.c b/drivers/video/fbdev/via/via_aux_sii164.c
> index ca1b35f033b1..87db6c98d680 100644
> --- a/drivers/video/fbdev/via/via_aux_sii164.c
> +++ b/drivers/video/fbdev/via/via_aux_sii164.c
> @@ -35,10 +35,10 @@ static void probe(struct via_aux_bus *bus, u8 addr)
>                  .addr   =       addr,
>                  .name   =       name};
>          /* check vendor id and device id */
> -       const u8 id[] = {0x01, 0x00, 0x06, 0x00}, len = ARRAY_SIZE(id);
> -       u8 tmp[len];
> +       const u8 id[] = {0x01, 0x00, 0x06, 0x00};
> +       u8 tmp[ARRAY_SIZE(id)];
>   
> -       if (!via_aux_read(&drv, 0x00, tmp, len) || memcmp(id, tmp, len))
> +       if (!via_aux_read(&drv, 0x00, tmp, sizeof(tmp)) || memcmp(id, tmp, sizeof(tmp)))
>                  return;
>   
>          printk(KERN_INFO "viafb: Found %s at address 0x%x\n", name, addr);
>
> Cheers,
>
> Tycho