[src/trunk]: src/sys/kern Change vnode operation lookup to return the resulti...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2358ff14a3d8
branches:  trunk
changeset: 326615:2358ff14a3d8
user:      hannken <hannken%NetBSD.org@localhost>
date:      Fri Feb 07 15:26:42 2014 +0000

description:
Change vnode operation lookup to return the resulting vnode *vpp unlocked.
Change cache_lookup() to return an unlocked vnode.

Discussed on tech-kern@

diffstat:

 sys/kern/vnode_if.src |  20 +++++---------------
 1 files changed, 5 insertions(+), 15 deletions(-)

diffs (41 lines):

diff -r eba560015d1f -r 2358ff14a3d8 sys/kern/vnode_if.src
--- a/sys/kern/vnode_if.src     Fri Feb 07 11:51:00 2014 +0000
+++ b/sys/kern/vnode_if.src     Fri Feb 07 15:26:42 2014 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: vnode_if.src,v 1.65 2014/01/23 10:11:55 hannken Exp $
+#      $NetBSD: vnode_if.src,v 1.66 2014/02/07 15:26:42 hannken Exp $
 #
 # Copyright (c) 1992, 1993
 #      The Regents of the University of California.  All rights reserved.
@@ -61,27 +61,17 @@
  
 #
 #% lookup     dvp     L L L
-#% lookup     vpp     - L -
+#% lookup     vpp     - U -
 #
-# XXX - the lookup locking protocol defies simple description.
 #    Note especially that *vpp may equal dvp.
 #
 #    More details:
-#     There are three types of lookups: ".", ".." (ISDOTDOT), and other.
-#     On successful lookup of ".", a reference is added to dvp, and it
-#          is returned in *vpp.
-#     To look up ISDOTDOT, dvp is unlocked, the ".." node is locked, and
-#          then dvp is relocked.  This preserves the protocol of always
-#          locking nodes from root ("/") downward and prevents deadlock.
-#     Other lookups find the named node (creating the vnode if needed) and
-#          return it, locked, in *vpp.
+#     All lookups find the named node (creating the vnode if needed) and
+#          return it, referenced and unlocked, in *vpp.
 #     On failure, *vpp is NULL, and *dvp is left locked.
-#      
-#     *vpp is always locked on return if the operation succeeds.
-#          Typically, if *vpp == dvp, you need to release twice, but
-#          unlock only once.
 #
 vop_lookup {
+       VERSION 2
        IN struct vnode *dvp;
        OUT WILLMAKE struct vnode **vpp;
        IN struct componentname *cnp;