From owner-freebsd-hackers@FreeBSD.ORG  Thu Feb 13 20:51:51 2014
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Date: Thu, 13 Feb 2014 12:51:50 -0800
Message-ID: <CALCNsJS6vFJU18F3VRR-T2RdtGNxd3fycUCkQ63BmGp29DAUMw@mail.gmail.com>
Subject: Debugging rw lock
From: Vijay Singh <vijju.singh@gmail.com>
To: hackers@freebsd.org
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I am running into an issue where an rw lock is read locked and never
unlocked, and causes a system to livelock. I was wondering if its possible
to figure out which thread owns the read lock?

It's the tcp pcbinfo lock.

(kgdb-amd64-7.4-08) show_rwlock rw
 name : tcp
 class: rw
 flags: {SLEEP, INITED, WITNESS, RECURSE, UPGRADABLE}
 state: RLOCK: 1 locks
 waiters: writers

Any help is appreciated.

-vijay