Messages in this thread | | | Date | Thu, 16 Aug 2007 18:02:32 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures |
| |
On Thu, Aug 16, 2007 at 01:20:26PM -0700, Christoph Lameter wrote: > On Thu, 16 Aug 2007, Chris Snook wrote: > > > atomic_dec() already has volatile behavior everywhere, so this is semantically > > okay, but this code (and any like it) should be calling cpu_relax() each > > iteration through the loop, unless there's a compelling reason not to. I'll > > allow that for some hardware drivers (possibly this one) such a compelling > > reason may exist, but hardware-independent core subsystems probably have no > > excuse. > > No it does not have any volatile semantics. atomic_dec() can be reordered > at will by the compiler within the current basic unit if you do not add a > barrier.
Yep. Or you can use atomic_dec_return() instead of using a barrier.
Thanx, Paul - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |