Re: [PATCH] net: fix race in the receive/select

Andi Kleen
2009-06-29T09:12:42Z

Jiri Olsa <jolsa@redhat.com> writes:

> Adding memory barrier to the __pollwait function paired with
> receive callbacks. The smp_mb__after_lock define is added,
> since {read|write|spin}_lock() on x86 are full memory barriers.

I was wondering did you see that race actually happening in practice?
If yes on which system?

At least on x86 I can't see how it happens. mb() is only a compile
time barrier and the compiler doesn't optimize over indirect callbacks
like __pollwait() anyways.

It might be still needed on some weaker ordered architectures, but did you
actually see it there?

-Andi

--
ak@linux.intel.com -- Speaking for myself only.