Re: Linus rollup

Richard Henderson
2003-01-30T01:52:32Z

On Wed, Jan 29, 2003 at 06:00:54PM -0800, Andrew Morton wrote:
> Andrea Arcangeli <andrea@suse.de> wrote:
> > if we hold the spinlock, the serialized memory can't be change under us,
> > so there's no need to put a read barrier, we only care that pre_sequence
> > is visible before the chagnes are visible and before post_sequence is
> > visible, hence only wmb() (after spin_lock and pre_sequence++) is
> > needed there and only rmb() is needed in the read-side.

Hmm. Perhaps I was confused about how these things are intended
to be used. If indeed the writer doesn't care about the order
in which pre/post_sequence are accessed, then wmb is sufficient
to keep their updates ordered.

r~