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

[Daniel K.]

Rolf Eike Beer wrote:
> Am Donnerstag, 20. Juli 2006 21:05 schrieb Panagiotis Issaris:
> > @@ -443,12 +442,11 @@ int con_clear_unimap(struct vc_data *vc,
> >  	p = (struct uni_pagedir *)*vc->vc_uni_pagedir_loc;
> >  	if (p && p->readonly) return -EIO;
> >  	if (!p || --p->refcount) {
> > -		q = (struct uni_pagedir *)kmalloc(sizeof(*p), GFP_KERNEL);
> > +		q = kzalloc(sizeof(*p), GFP_KERNEL);
> >  		if (!q) {
> >  			if (p) p->refcount++;
> >  			return -ENOMEM;
> >  		}
> > -		memset(q, 0, sizeof(*q));
> >  		q->refcount=1;
> >  		*vc->vc_uni_pagedir_loc = (unsigned long)q;
> >  	} else {
>
> This one still changes the way the code works. Before your patch *p will be 
> always zeroed out. Now if p is there before it will keep it's contents.

No, it doesn't, the data at *p is/was not zeroed inside the if { .. } block.
Read carefully, the multiple statements on one line obfuscations might
have thrown you off. 

However, it is slightly confusing that the value assigned to `q' is
kzalloced using sizeof(*p). It is an improvement though, as the old version
kmalloced using sizeof(*p), and memset using sizeof(*q).
That was really strange.


Daniel K.
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