Author: kib
Date: Sat Nov 9 20:30:13 2013
New Revision: 257898
URL: http://svnweb.freebsd.org/changeset/base/257898
Log:
Both vn_close() and VFS_PROLOGUE() evaluate vp->v_mount twice, without
holding the vnode lock; vp->v_mount is checked first for NULL
equiality, and then dereferenced if not NULL. If vnode is reclaimed
meantime, second dereference would still give NULL. Change
VFS_PROLOGUE() to evaluate the mp once, convert MNTK_SHARED_WRITES and
MNTK_EXTENDED_SHARED tests into inline functions.
Reviewed by: alc
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Modified:
head/sys/kern/vfs_lookup.c
head/sys/kern/vfs_vnops.c
head/sys/sys/mount.h
Modified: head/sys/kern/vfs_lookup.c
==============================================================================
--- head/sys/kern/vfs_lookup.c Sat Nov 9 20:11:21 2013 (r257897)
+++ head/sys/kern/vfs_lookup.c Sat Nov 9 20:30:13 2013 (r257898)
@@ -424,13 +424,8 @@ needs_exclusive_leaf(struct mount *mp, i
* extended shared operations, then use a shared lock for the
* leaf node, otherwise use an exclusive lock.
*/
- if (flags & ISOPEN) {
- if (mp != NULL &&
- (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED))
- return (0);
- else
- return (1);
- }
+ if ((flags & ISOPEN) != 0)
+ return (!MNT_EXTENDED_SHARED(mp));
/*
* Lookup requests outside of open() that specify LOCKSHARED
Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c Sat Nov 9 20:11:21 2013 (r257897)
+++ head/sys/kern/vfs_vnops.c Sat Nov 9 20:30:13 2013 (r257898)
@@ -360,8 +360,8 @@ vn_close(vp, flags, file_cred, td)
struct mount *mp;
int error, lock_flags;
- if (vp->v_type != VFIFO && !(flags & FWRITE) && vp->v_mount != NULL &&
- vp->v_mount->mnt_kern_flag & MNTK_EXTENDED_SHARED)
+ if (vp->v_type != VFIFO && (flags & FWRITE) == 0 &&
+ MNT_EXTENDED_SHARED(vp->v_mount))
lock_flags = LK_SHARED;
else
lock_flags = LK_EXCLUSIVE;
Modified: head/sys/sys/mount.h
==============================================================================
--- head/sys/sys/mount.h Sat Nov 9 20:11:21 2013 (r257897)
+++ head/sys/sys/mount.h Sat Nov 9 20:30:13 2013 (r257898)
@@ -362,8 +362,19 @@ void __mnt_vnode_markerfree_act
#define MNTK_LOOKUP_SHARED 0x40000000 /* FS supports shared lock lookups */
#define MNTK_NOKNOTE 0x80000000 /* Don't send KNOTEs from VOP
hooks */
-#define MNT_SHARED_WRITES(mp) (((mp) != NULL) && \
- ((mp)->mnt_kern_flag & MNTK_SHARED_WRITES))
+static inline int
+MNT_SHARED_WRITES(struct mount *mp)
+{
+
+ return (mp != NULL && (mp->mnt_kern_flag & MNTK_SHARED_WRITES) != 0);
+}
+
+static inline int
+MNT_EXTENDED_SHARED(struct mount *mp)
+{
+
+ return (mp != NULL && (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED) != 0);
+}
/*
* Sysctl CTL_VFS definitions.
@@ -636,10 +647,12 @@ struct vfsops {
vfs_statfs_t __vfs_statfs;
#define VFS_PROLOGUE(MP) do {
\
+ struct mount *mp__; \
int _enable_stops; \
\
- _enable_stops = ((MP) != NULL && \
- ((MP)->mnt_vfc->vfc_flags & VFCF_SBDRY) && sigdeferstop())
+ mp__ = (MP); \
+ _enable_stops = (mp__ != NULL && \
+ (mp__->mnt_vfc->vfc_flags & VFCF_SBDRY) && sigdeferstop())
#define VFS_EPILOGUE(MP)
\
if (_enable_stops) \
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
