Re: [patch 1/7] slab: introduce kzfree()

On Thu, 19 Feb 2009, Pekka Enberg wrote:
Hugh Dickins wrote:

But I fail to see it as a justification for kzfree(const void *):
if someone has "const char *string = kmalloc(size)" and then
wants that string zeroed before it is freed, then I think it's
quite right to cast out the const when calling kzfree().

Quite frankly, I fail to see how kzfree() is fundamentally different from
kfree(). I don't see kzfree() as a memset() + kfree() but rather as a kfree()
"and make sure no one sees my data". So the zeroing happens _after_ you've
invalidated the pointer with kzfree() so there's no "zeroing of buffer going
on".

Well, that would be one way of picturing it, yes.
Imagine the "z" as for "zap" rather than "zero",
and the mechanism as opaque as Hannes suggests.

So the way I see it, Linus' argument for having const for kfree() applies
to kzfree().

That said, if you guys think it's a merge blocker, by all means remove the
const. I just want few less open-coded ksize() users, that's all.

I wouldn't call it a merge blocker, no; though I still
think it makes far more sense without the "const" there.

Hugh
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