Date: Thu, 6 Dec 2012 11:49:10 GMT From: Bas Smeelen <b.smeelen@ose.nl> To: freebsd-gnats-submit@FreeBSD.org Subject: docs/174226: [patch] faq: lock-order-reversal Message-ID: <201212061149.qB6BnAD3015250@red.freebsd.org> Resent-Message-ID: <201212061150.qB6Bo0bj039837@freefall.freebsd.org>
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>Number: 174226 >Category: docs >Synopsis: [patch] faq: lock-order-reversal >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-doc >State: open >Quarter: >Keywords: >Date-Required: >Class: update >Submitter-Id: current-users >Arrival-Date: Thu Dec 06 11:50:00 UTC 2012 >Closed-Date: >Last-Modified: >Originator: Bas Smeelen >Release: 9.1 >Organization: >Environment: FreeBSD cfd 9.1-RELEASE FreeBSD 9.1-RELEASE #1 r243880: Wed Dec 5 08:15:54 CET 2012 root@cfd:/usr/obj/usr/src/sys/GENERIC i386 >Description: >How-To-Repeat: >Fix: Index: book.xml =================================================================== --- book.xml (revision 40280) +++ book.xml (working copy) @@ -3488,9 +3488,20 @@ </question> <answer> - <para>An answer for this question can be found in the &os; - Glossary, see <ulink - url="&url.books.handbook;/freebsd-glossary.html#lor-glossary">LOR</ulink>.</para> + <para>The &os; kernel uses a number of resource locks to + arbitrate contention for those resources. A run-time + lock diagnostic system found in &os.current; kernels + (but removed for releases), called &man.witness.4;, + detects the potential for deadlocks due to locking errors. + (&man.witness.4; is actually slightly conservative, so + it is possible to get false positives.) A true positive + report indicates that <quote>if you were unlucky, a deadlock would + have happened here</quote>.</para> + + <para>True positive LORs tend to get fixed quickly, so + check &a.current.url; and the + <ulink url="http://sources.zabbadoz.net/freebsd/lor.html">LORs Seen + </ulink> page before posting to the mailing lists.</para> </answer> </qandaentry> >Release-Note: >Audit-Trail: >Unformatted:
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