cvs commit: src/sys/fs/pseudofs pseudofs_vnops.c

[Don Lewis]

On  1 Jun, Dag-Erling Smorgrav wrote:
> Don Lewis <truckman at FreeBSD.org> writes:
>>   Modified files:
>>     sys/fs/pseudofs      pseudofs_vnops.c 
>>   Log:
>>   Don't unlock the parent directory vnode twice if the ISDOTDOT flag
>>   is set.
> 
> des at dwp ~% grep pseudofs /usr/src/MAINTAINERS
> pseudofs        des     Advance notification requested.

Sorry, though ...

------ Forwarded message ------
    From: Don Lewis <truckman at FreeBSD.org>
 Subject: possible patch for vnode double unlock in pfs_lookup()
    Date: Wed, 21 May 2003 23:20:49 -0700 (PDT)
      To: des at FreeBSD.org, jeff at FreeBSD.org
      Cc: current at FreeBSD.org

If the ISDOTDOT flag is set and the lockparent or ISLASTCN flags are not
set, pfs_lookup() unlocks the same vnode twice.  This can be observed by
running
	find / -print
with the DEBUG_VFS_LOCKS kernel option enabled.

I think the following is the correct patch:

I believe that it is safe to defer committing a fix until after
5.1-RELEASE.


Index: sys/fs/pseudofs/pseudofs_vnops.c
===================================================================
RCS file: /home/ncvs/src/sys/fs/pseudofs/pseudofs_vnops.c,v
retrieving revision 1.35
diff -u -r1.35 pseudofs_vnops.c
--- sys/fs/pseudofs/pseudofs_vnops.c	2 Mar 2003 22:23:45 -0000	1.35
+++ sys/fs/pseudofs/pseudofs_vnops.c	22 May 2003 04:40:09 -0000
@@ -411,7 +411,8 @@
 		vn_lock(vn, LK_EXCLUSIVE|LK_RETRY, cnp->cn_thread);
 		cnp->cn_flags &= ~PDIRUNLOCK;
 	}
-	if (!lockparent || !(cnp->cn_flags & ISLASTCN))
+	if ((!lockparent || !(cnp->cn_flags & ISLASTCN)) &&
+	    !(cnp->cn_flags & ISDOTDOT))
 		VOP_UNLOCK(vn, 0, cnp->cn_thread);
 
 	/*

------ End forwarded message ------

The patch I committed DeMorgan-ized the expression so that it isn't
quite as !-happy.

You might also want to look for the message I sent to -current about 8
hours ago with the subject "vnode locking problem in pseudofs/procfs".