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Date: Thu, 6 Dec 2012 11:49:10 GMT
From: Bas Smeelen <b.smeelen@ose.nl>
To: freebsd-gnats-submit@FreeBSD.org
Subject: [patch] faq: lock-order-reversal
X-Send-Pr-Version: www-3.1
X-GNATS-Notify:

>Number:         174226
>Category:       docs
>Synopsis:       [patch] faq: lock-order-reversal
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    eadler
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          update
>Submitter-Id:   current-users
>Arrival-Date:   Thu Dec 06 11:50:00 UTC 2012
>Closed-Date:    Sat Feb 23 15:00:44 UTC 2013
>Last-Modified:  Sat Feb 23 15:00:44 UTC 2013
>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:
Responsible-Changed-From-To: freebsd-doc->eadler 
Responsible-Changed-By: eadler 
Responsible-Changed-When: Thu Dec 6 12:37:58 UTC 2012 
Responsible-Changed-Why:  
I'll take it. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=174226 

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: docs/174226: commit references a PR
Date: Sat, 23 Feb 2013 14:50:47 +0000 (UTC)

 Author: eadler
 Date: Sat Feb 23 14:50:24 2013
 New Revision: 41036
 URL: http://svnweb.freebsd.org/changeset/doc/41036
 
 Log:
   Update the lock-order-reversal question
   
   PR:		docs/174226
   Submitted by:	Bas Smeelen <b.smeelen@ose.nl>
   Reviewed by:	Erich Dollansky <erichsfreebsdlist@alogt.com>
   Reviewed by:	avg
   Reviewed by:	bjk
   Discussed with:	wblock
   Approved by:	??? (mentor)
 
 Modified:
   head/en_US.ISO8859-1/books/faq/book.xml
 
 Modified: head/en_US.ISO8859-1/books/faq/book.xml
 ==============================================================================
 --- head/en_US.ISO8859-1/books/faq/book.xml	Sat Feb 23 14:49:59 2013	(r41035)
 +++ head/en_US.ISO8859-1/books/faq/book.xml	Sat Feb 23 14:50:24 2013	(r41036)
 @@ -2493,9 +2493,19 @@ kern.timecounter.hardware: TSC -&gt; i82
  	</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 certain 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.
 +	    (It is possible to get false positives, as &man.witness.4;
 +	    is slightly conservative.) A true positive report
 +	    indicates that "if you were unlucky, a deadlock would have
 +	    happened here">.</para>
 +
 +	  <para>Problematic <acronym>LOR</acronym>s tend to get fixed
 +	    quickly, so check &a.current.url; before posting to the
 +	    mailing lists.</para>
  	</answer>
        </qandaentry>
  
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State-Changed-From-To: open->closed 
State-Changed-By: eadler 
State-Changed-When: Sat Feb 23 15:00:42 UTC 2013 
State-Changed-Why:  
Committed. Thanks! 

http://www.freebsd.org/cgi/query-pr.cgi?pr=174226 
>Unformatted:
