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

On 7/17/05, Jesper Juhl [off-list ref] 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];
}

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.




-- 
Jon Smirl
jonsmirl@gmail.com