Re: [PATCH] Use NULL instead of integer 0 in security/selinux/

[Roland Dreier <roland@topspin.com>]

    Linus> I really don't see the point of complaining about the
    Linus> fixes. There's just _no_ way to say that "0" is more
    Linus> readable than "NULL" in any of the cases.  I dare you -
    Linus> show _one_ case where a 0/NULL patch was wrong or even
    Linus> remotely debatable. I dare you.

I don't know if any of the 0/NULL kernel patches were of this form,
but I've seen sparse complain about this in my code and found it
somewhat annoying.  I think the following is at least remotely debatable...

Suppose I have

	struct foo {
		int a;
		int b;
	};

then sparse is perfectly happy with someone clearing out a struct foo
like this:

	struct foo bar = { 0 };

but then if someone changes struct foo to be

	struct foo {
		void *x;
		int a;
		int b;
	};

sparse will complain about that initialization, and all of the fixes
I can think of seem somewhat worse than the original to me:

	struct foo bar = { NULL };   /* will I have to change this
                                        again if struct foo changes? */

or

	struct foo bar = { .a = 0 }; /* why do I have to name a member? */

or

	struct foo bar;
	memset(&bar, 0, sizeof bar); /* WRONG if a null pointer is not
                                        the bit pattern 0 */

 - Roland