Date: Wed, 06 Aug 2003 16:22:30 -0700 From: Sam Leffler <sam@errno.com> To: Ted Unangst <tedu@stanford.edu>, freebsd-hackers@freebsd.org Subject: Re: possible deadlocks? Message-ID: <1650093869.1060186950@melange.errno.com> In-Reply-To: <Pine.GSO.4.44.0308061506120.29218-100000@saga0.Stanford.EDU> References: <Pine.GSO.4.44.0308061506120.29218-100000@saga0.Stanford.EDU>
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> My advisor Dawson Engler has written a deadlock detector, and we'd like
> some verification. They look like bugs, unless there is some other reason
> why two call chains cannot happen at the same time.
>
Dawson? Hey Dawson!
> second one in bpf, between bpfif_lock and bpfd_lock.
>
> thread 1:
> bpf_tap() /* or bpf_mtap */
> BPFIF_LOCK(bp); /* gets this lock */
> for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
> BPFD_LOCK(d); /* waits for thread 2 */
>
> thread 2:
> bpf_setdlt()
> BPFD_LOCK(d); /* gets lock */
> bpf_detachd(d); /* or bpf_attachd */
> BPFIF_LOCK(bp); /* waits for thread 1 */
Yeah, this is my bad. Will have to look if it's possible.
Does this mean you're going to prove -current is "lockably corrrect"? :)
Sam
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