linux-kernel - Re: >Re: [RFC] should VM_BUG_ON(cond) really evaluate cond

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Message-ID: <CA+55aFz-mp8k7qdF3LaOjgX19TbzrCirGuCmGwqVMq9SwQ8yvw@mail.gmail.com>
Date:	Sun, 30 Oct 2011 10:48:17 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Ben Hutchings <bhutchings@...arflare.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: >Re: [RFC] should VM_BUG_ON(cond) really evaluate cond

On Sun, Oct 30, 2011 at 10:41 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
> Changing atomic_read(const atomic_t *v) prototype to
> atomic_read(atomic_t *v) is not an option.

Why not?

    #define atomic_read(v)     ACCESS_AT_MOST_ONCE((v)->counter)

seems to be the cleanest thing.

And if you don't think this is "an option", I really can't see why you
care about the extra instructions in the code stream either.

> 4) macro (I personnaly dont like it)
> #define atomic_read(v) ACCESS_AT_MOST_ONCE(*(int *)&(v)->counter)

Why the *hell* would you have that cast there?

If somebody passes "const atomic_t"'s around, then just shoot the
bastard. The concept makes no sense.

Grepping for "const atomic_t" shows absolutely *zero* users, except
for the crazy inline function declaration itself.

Stop the insanity already. Get rid of the f*cking "const".

                      Linus
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