cvs commit: src/sys/kern subr_turnstile.c
rwatson at FreeBSD.org
Tue Sep 9 10:09:36 UTC 2008
On Mon, 8 Sep 2008, John Baldwin wrote:
> SVN rev 182879 on 2008-09-08 21:40:15Z by jhb
> - Reduce scope of #ifdef's in uma_zcreate() call in init_turnstile0().
> - Set UMA_ZONE_NOFREE so that the per-turnstile spin locks are type stable
> to avoid a race where one thread might dereference a lock in a free'd
> turnstile that was previously used by another thread.
Is this a feature or a workaround for a bug? Normally in the above scenario
we would consider use-after-free a bug or symptom of a larger architectural
problem rather than a feature. At least, that's what I consider similar use
of UMA_ZONE_NOFREE where it persists in the network stack :-).
Robert N M Watson
University of Cambridge
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