Re: [PATCH] drivers: Conversions from kmalloc+memset to k(z|c)alloc.

Panagiotis Issaris
2006-07-20T18:03:41Z

Hi,

On wo, 2006-07-19 at 14:53 +0100, Paulo Marques wrote:
> > [...]
> > --- a/drivers/char/consolemap.c
> > +++ b/drivers/char/consolemap.c
> > @@ -192,11 +192,9 @@ static void set_inverse_transl(struct vc
> > q = p->inverse_translations[i];
> >
> > if (!q) {
> > - q = p->inverse_translations[i] = (unsigned char *)
> > - kmalloc(MAX_GLYPH, GFP_KERNEL);
> > + q = p->inverse_translations[i] = kzalloc(MAX_GLYPH, GFP_KERNEL);
> > if (!q) return;
> > }
> > - memset(q, 0, MAX_GLYPH);
>
> This changes semantics here. Before, the data pointed by q was always
> cleared whether it was malloc'ed or not. Now it is only cleared if it is
> malloc'ed. I haven't checked the code to find out if this is ok, though.
Oops :( My bad. I've removed this from my updated patch. Thanks!

>[...]
> > - struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
> > - memset(np, 0, sizeof(*np));
> > + struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
> > np->shift = p->shift - CARDMAP_ORDER;
> > np->parent = p;
> > p->ptr[i] = np;
>
> This is not your fault, but this code is using the return value from
> kmalloc (or kzalloc, now) without checking for NULL.
Oops again. I should have noticed that. Thanks again!

> > --- a/drivers/video/offb.c
> > +++ b/drivers/video/offb.c
> > @@ -376,13 +376,12 @@ static void __init offb_init_fb(const ch
> >
> > size = sizeof(struct fb_info) + sizeof(u32) * 17;
> >
> > - info = kmalloc(size, GFP_ATOMIC);
> > + info = kzalloc(size, GFP_ATOMIC);
> >
> > if (info == 0) {
>
> Again, not your fault, but "info == 0"? If you're doing a new version of
> the patch, please change this to NULL or !info, so that we don't confuse
> human readers :)
Thanks for the hint! I've modified my patch accordingly.

Cheers,
Takis