Date: Fri, 13 Feb 2004 11:30:23 -0800 (PST) From: fabbri <fabbri@isilon.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/61122: rpc.lockd coredumps with SIGNAL 11 Message-ID: <200402131930.i1DJUNr2099180@freefall.freebsd.org>
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The following reply was made to PR kern/61122; it has been noted by GNATS.
From: fabbri <fabbri@isilon.com>
To: freebsd-gnats-submit@FreeBSD.org,
ohartman@mail.physik.uni-mainz.de
Cc:
Subject: Re: kern/61122: rpc.lockd coredumps with SIGNAL 11
Date: Fri, 13 Feb 2004 11:26:44 -0800
I have a patch for at least one cause of this.
Description:
One of the pair of processes implemening nfs locking was crashing with
a seg-fault when it handled locks which were contended over a long
period.
- In the case where it processed the last element in the list,
retry_blockingfilelocklist() would dereference a null pointer trying
to LIST_INSERT_BEFORE(null, ..).
- Rework the list iteration to keep track of the previous element so
we can correctly do a O(1) reinsertion in a LIST.
Patch:
Index: lockd_lock.c
===================================================================
RCS file: /usr/local/ncvs/atera/src/usr.sbin/rpc.lockd/lockd_lock.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 lockd_lock.c
--- lockd_lock.c 9 Mar 2002 02:35:14 -0000 1.1.1.1
+++ lockd_lock.c 13 Feb 2004 19:20:12 -0000
@@ -1226,11 +1226,12 @@ void
retry_blockingfilelocklist(void)
{
/* Retry all locks in the blocked list */
- struct file_lock *ifl, *nfl; /* Iterator */
+ struct file_lock *ifl, *nfl, *pfl; /* Iterator */
enum partialfilelock_status pflstatus;
debuglog("Entering retry_blockingfilelocklist\n");
+ pfl = NULL;
ifl = LIST_FIRST(&blockedlocklist_head);
debuglog("Iterator choice %p\n",ifl);
@@ -1260,9 +1261,14 @@ retry_blockingfilelocklist(void)
} else {
/* Reinsert lock back into same place in blocked list */
debuglog("Replacing blocked lock\n");
- LIST_INSERT_BEFORE(nfl, ifl, nfslocklist);
+ if (pfl != NULL)
+ LIST_INSERT_AFTER(pfl, ifl, nfslocklist);
+ else
+ LIST_INSERT_HEAD(&blockedlocklist_head, ifl,
+ nfslocklist);
}
+ pfl = ifl;
/* Valid increment behavior regardless of state of ifl */
ifl = nfl;
}
--
<< Aaron Fabbri o Developer, Filesystems Team o isilon.com >>
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