On Fri, 17 Aug 2007, Nick Piggin wrote:
> Stefan Richter wrote: > [...] > Just use spinlocks if you're not absolutely clear about potential > races and memory ordering issues -- they're pretty cheap and simple. I fully agree with this. As Paul Mackerras mentioned elsewhere, a lot of authors sprinkle atomic_t in code thinking they're somehow done with *locking*. This is sad, and I wonder if it's time for a Documentation/atomic-considered-dodgy.txt kind of document :-) > > Sure, now > > that I learned of these properties I can start to audit code and insert > > barriers where I believe they are needed, but this simply means that > > almost all occurrences of atomic_read will get barriers (unless there > > already are implicit but more or less obvious barriers like msleep). > > You might find that these places that appear to need barriers are > buggy for other reasons anyway. Can you point to some in-tree code > we can have a look at? Such code was mentioned elsewhere (query nodemgr_host_thread in cscope) that managed to escape the requirement for a barrier only because of some completely un-obvious compilation-unit-scope thing. But I find such an non-explicit barrier quite bad taste. Stefan, do consider plunking an explicit call to barrier() there. Satyam - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html