Re: [PATCH] add NULL short circuit to fb_dealloc_cmap()

[Geert Uytterhoeven <geert@linux-m68k.org>]

On Sun, 17 Jul 2005, Jon Smirl wrote:
> On 7/17/05, Jesper Juhl <jesper.juhl@gmail.com> wrote:
> > Resource freeing functions should generally be safe to call with NULL pointers.
> > Why?
> >  - there is some precedence in the kernel for this for deallocation functions.
> >  - removes the need for callers to check pointers for NULL.
> >  - space is saved overall by less code to test pointers for NULL all over the place.
> >  - removes possible NULL pointer dereferences when a caller forgot to check.
> > 
> > This patch makes  fb_dealloc_cmap()  safe to call with a NULL pointer argument.
> 
> The fb cmap copde would be a lot simpler if it did everything with a
> single allocation instead of five. Make a super cmap struct:
> 
> struct fb_super_cmap {
>    struct fb_cmap cmap;
>    __u16 red[255];
>    __u16 blue[255];
>    __u16 green[255];
>    __u16 transp[255];
                  ^^^
I assume you meant 256?

> }
> 
> Then adjust the code as need. Have the embedded cmap struct point to
> the fields in the super_cmap and the drivers don't have to be changed.

What if your colormap has more than 256 entries?

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
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