On Wed, 1 Aug 2012, Konrad Rzeszutek Wilk wrote: > On Fri, Jul 27, 2012 at 10:28:25AM +0100, Ian Campbell wrote: > > On Thu, 2012-07-26 at 17:37 +0100, Konrad Rzeszutek Wilk wrote: > > > On Thu, Jul 26, 2012 at 04:33:46PM +0100, Stefano Stabellini wrote: > > > > sync_bitops functions are equivalent to the SMP implementation of the > > > > original functions, independently from CONFIG_SMP being defined. > > > > > > So why can't the code be changed to use that? Is it that > > > the _set_bit, _clear_bit, etc are not available with !CONFIG_SMP? > > > > _set_bit etc are not SMP safe if !CONFIG_SMP. But under Xen you might be > > communicating with a completely external entity who might be on another > > CPU (e.g. two uniprocessor guests communicating via event channels and > > grant tables). So we need a variant of the bit ops which are SMP safe > > even on a UP kernel. > > > > The users are common code and the sync_foo vs foo distinction matters on > > some platforms (e.g. x86 where a UP kernel would omit the LOCK prefix > > for the normal ones). > > OK, that makes sense. Stefano can you include that comment in the git > commit description and in the sync_bitops.h file please?
Yep, I'll do that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
