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

[Thomas Gleixner]

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?

Answer: No difference and nothing is safer because it's exactly the same.

In general we use sizeof(*p) simply because when the data type of p changes
you don't have to update the code, it just works and stays correct.

Thanks,

	tglx