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

[Rolf Eike Beer <eike-kernel@sf-tec.de>]

Panagiotis Issaris wrote:

> > > @@ -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.
>
> Hmm. I do not really see the functional change here: If the memory
> allocation failed, then in both cases, q will be zero and the function
> will return. If the memory allocation succeeds, then in both cases a
> memset will occur. Is it more subtle than that?

You're right, I got somehow confused by this p and q stuff.

Eike