Re: [PATCH] x86/mm/mem_encrypt_identity : fix error useage to sizeof

[Thomas Gleixner]

On Tue, 15 Jan 2019, Thomas Gleixner wrote:

> On Tue, 15 Jan 2019, Juergen Gross wrote:
> > On 15/01/2019 11:13, Thomas Gleixner wrote:
> > > On Mon, 7 Jan 2019, peng.hao2@xxxxxxxxxx wrote:
> > > 
> > >>>> Fix error usage to sizeof. It should not use sizeof to pointer.
> > >>>
> > >>> .... because?
> > >>>
> > >>> The commit message needs to explain what the potential issue could be
> > >>> and why it doesn't matter in this case.
> > >> I see the definition of pte_t may be more than sizeof(unsigned long).
> > >> So I think sizeof(pte_t) is safer.
> > > 
> > > What exactly is the difference between:
> > > 
> > > 	pte_t	*p;
> > > 
> > > 	sizeof(*p)
> > > 
> > > and
> > > 
> > > 	sizeof(pte_t)
> > > 
> > > and what is safer about the latter?
> > 
> > Please note that the current code is using sizeof(p) instead of sizeof(*p).
> 
> Ooops. That's wrong indeed, but we should not change it to sizeof(pte_t)
> and change it to sizeof(*p) instead.

Which is what the patch actually does. Just the above reply:

> > >> So I think sizeof(pte_t) is safer.

confused the hell out of me. -ENOTENOUGHCOFFEE