Re: [RFC][PATCH 5/5] arch: Sanitize atomic_t bitwise ops

From: Peter Zijlstra
Date: Thu Feb 06 2014 - 13:09:44 EST


On Thu, Feb 06, 2014 at 09:56:54AM -0800, Linus Torvalds wrote:
> On Thu, Feb 6, 2014 at 9:52 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> It's the "_return" variants. As far as I can tell, there are exactly
> ZERO users of that stuff, and they are BAD BAD BAD.
>
> On x86, those things would cause a cmpxchg loop, and the bad
> read-for-shared-before-acquire cacheline pattern.
>
> So why indirectly encourage people to add users for a bad operation?

OK, I'll not generate the _return() variants.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/