LOR route vr0

Robert Watson rwatson at FreeBSD.org
Sun Aug 28 04:20:17 GMT 2005

On Sat, 27 Aug 2005, M. Warner Losh wrote:

> : Correct.  'tcp' reflects the global TCP state tables (pcbinfo) locks, and
> : 'tcpinp' is for individual PCBs.  If you acquire first a tcpinp and then
> : tcp, the above settings should cause WITNESS to generate a lock order
> : warning.  Likewise, both tcp and tcpinp preceed so_snd, so if you acquire
> : a protocol lock after a socket lock, it will get unhappy.  WITNESS handles
> : transitive relationships, so it gets connected up to the rest of the lock
> : graph, explicit and implicit, so indirect violations of orders are fully
> : handled.
> OK.  I've been seeing similar LORs in ed, sn, iwi (ed is my locked 
> version of ed, not in tree GIANT locked ed).
> I've made the following changes, and the LORs go away (except for one, 
> which was unrelated).  I further don't get the first place where they 
> locks happen that caused the original LORs, so I'm mightly confused.

Hmm.  I've seen another identical report recently -- that when a lock 
order is put into WITNESS, reversals against it are not reported.  I 
wonder if we've got a witness bug on our hands?

Robert N M Watson

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