Re: [PATCH] some kmalloc/memset ->kzalloc (tree wide)

[yoann padioleau]

On 7 juil. 07, at 15:07, Tilman Schmidt wrote:

> Am 06.07.2007 18:51 schrieb Yoann Padioleau:
> > @@
> > expression E1,E2,E3;
> > @@
> >
> > - kzalloc(E1 * E2,E3)
> > + kcalloc(E1,E2,E3)
>
> This misses the semantic distinction between the first and second
> arguments of kcalloc(). The first argument is supposed to be the
> number of elements to allocate and the second their size. As a
> consequence, the following hunks in your pathc are wrong:

Yes you are right. Andrew Morton fixed the problem in a
subsequent patch.

I should have written a more precise semantic patch such as

@@
expression E;
constant c;
type T;
@@

- kzalloc(sizeof(T) * c, E)
+ kcalloc(c, sizeof(T), E)


Note that sometimes the code is written as  kzalloc(c * sizeof(T), E)
as in   kzalloc(2 * sizeof(struct resource), GFP_KERNEL)  but
our transformation engine can handle the commutativity of '*' and still
performs the right transformation.


> > diff --git a/arch/arm/mach-iop13xx/pci.c b/arch/arm/mach-iop13xx/ 
> > pci.c
> > index 9d63d7f..b84955f 100644
> > --- a/arch/arm/mach-iop13xx/pci.c
> > +++ b/arch/arm/mach-iop13xx/pci.c
> > @@ -1002,11 +1002,10 @@ int iop13xx_pci_setup(int nr, struct pci
> >  	if (nr > 1)
> >  		return 0;
> >
> > -	res = kmalloc(sizeof(struct resource) * 2, GFP_KERNEL);
> > +	res = kcalloc(sizeof(struct resource), 2, GFP_KERNEL);
> >  	if (!res)
> >  		panic("PCI: unable to alloc resources");
> >
> > -	memset(res, 0, sizeof(struct resource) * 2);
> >
> >  	/* 'nr' assumptions:
> >  	 * ATUX is always 0


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