Re: [PATCH]use kzalloc in vfs where appropriate

[Arjan van de Ven <arjan@infradead.org>]

On Sun, 2006-03-19 at 14:29 +0100, Oliver Neukum wrote:
> Am Samstag, 18. März 2006 11:55 schrieb Arjan van de Ven:
> > On Sat, 2006-03-18 at 11:44 +0100, Oliver Neukum wrote:
> > > Am Freitag, 17. März 2006 22:08 schrieb Matthew Wilcox:
> > > > On Fri, Mar 17, 2006 at 09:58:14PM +0100, Oliver Neukum wrote:
> > > > > --- a/fs/bio.c	2006-03-11 23:12:55.000000000 +0100
> > > > > +++ b/fs/bio.c	2006-03-17 16:44:49.000000000 +0100
> > > > > @@ -635,12 +635,10 @@
> > > > >  		return ERR_PTR(-ENOMEM);
> > > > >  
> > > > >  	ret = -ENOMEM;
> > > > > -	pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
> > > > > +	pages = kzalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
> > > > 
> > > > Didn't we just discuss this one and conclude it needed to use kcalloc
> > > > instead?
> > > 
> > > I've found some discussion in the archive, but no conclusion. Could you
> > > elaborate?
> > 
> > kcalloc is the array allocator.
> > Here.. you're allocating an array of nr_pages worth of pointers.
> > kcalloc does extra checks because it KNOWS it's an array...
> 
> I see. A patch is coming.
> Shouldn't this check from slab.h:
> 
> 	if (n != 0 && size > INT_MAX / n)
> 		return NULL;
> 
> carry an "unlikely"?

gcc is most likely smart enough for that already, and most of the time n
is a compile time constant already :)

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