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Remove unnecessary locking around vn_fullpath(). The vnode lock for the

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vnode in question does not need to be held.  All the data structures used
during the name lookup are protected by the global name cache lock.
Instead, the caller merely needs to ensure a reference is held on the
vnode (such as vhold()) to keep it from being freed.

In the case of procfs' <pid>/file entry, grab the process lock while we
gain a new reference (via vhold()) on p_textvp to fully close races with
execve(2).

For the kern.proc.vmmap sysctl handler, use a shared vnode lock around
the call to VOP_GETATTR() rather than an exclusive lock.

MFC after:	1 month
This commit is contained in:
John Baldwin 2008-11-04 19:04:01 +00:00
parent 2ef42c06d6
commit 2ff47c5f18
5 changed files with 12 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/dev/hwpmc/hwpmc_mod.c
View File

@ -680,9 +680,7 @@ pmc_getfilename(struct vnode *v, char **fullpath, char **freepath)
*fullpath = "unknown";
*freepath = NULL;
vn_lock(v, LK_CANRECURSE | LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(curthread, v, fullpath, freepath);
VOP_UNLOCK(v, 0);
}
/*

12
sys/fs/procfs/procfs.c
View File

@ -70,17 +70,13 @@ procfs_doprocfile(PFS_FILL_ARGS)
char *fullpath = "unknown";
char *freepath = NULL;
struct vnode *textvp;
int err;
PROC_LOCK(p);
textvp = p->p_textvp;
VI_LOCK(textvp);
vholdl(textvp);
err = vn_lock(textvp, LK_EXCLUSIVE | LK_INTERLOCK);
vdrop(textvp);
if (err)
return (err);
vhold(textvp);
PROC_UNLOCK(p);
vn_fullpath(td, textvp, &fullpath, &freepath);
VOP_UNLOCK(textvp, 0);
vdrop(textvp);
sbuf_printf(sb, "%s", fullpath);
if (freepath)
free(freepath, M_TEMP);

5
sys/fs/procfs/procfs_map.c
View File

@ -175,10 +175,9 @@ procfs_doprocmap(PFS_FILL_ARGS)
shadow_count = obj->shadow_count;
VM_OBJECT_UNLOCK(obj);
if (vp != NULL) {
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(td, vp, &fullpath, &freepath);
vput(vp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vrele(vp);
VFS_UNLOCK_GIANT(vfslocked);
}
} else {

10
sys/kern/kern_descrip.c
View File

@ -2537,10 +2537,9 @@ export_vnode_for_sysctl(struct vnode *vp, int type,
freepath = NULL;
fullpath = "-";
FILEDESC_SUNLOCK(fdp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(curthread, vp, &fullpath, &freepath);
vput(vp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vrele(vp);
VFS_UNLOCK_GIANT(vfslocked);
strlcpy(kif->kf_path, fullpath, sizeof(kif->kf_path));
if (freepath != NULL)
@ -2708,10 +2707,9 @@ sysctl_kern_proc_filedesc(SYSCTL_HANDLER_ARGS)
freepath = NULL;
fullpath = "-";
FILEDESC_SUNLOCK(fdp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(curthread, vp, &fullpath, &freepath);
vput(vp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vrele(vp);
VFS_UNLOCK_GIANT(vfslocked);
strlcpy(kif->kf_path, fullpath,
sizeof(kif->kf_path));

4
sys/kern/kern_proc.c
View File

@ -1440,11 +1440,11 @@ sysctl_kern_proc_vmmap(SYSCTL_HANDLER_ARGS)
kve->kve_shadow_count = obj->shadow_count;
VM_OBJECT_UNLOCK(obj);
if (vp != NULL) {
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(curthread, vp, &fullpath,
&freepath);
cred = curthread->td_ucred;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_SHARED | LK_RETRY);
if (VOP_GETATTR(vp, &va, cred) == 0) {
kve->kve_fileid = va.va_fileid;
kve->kve_fsid = va.va_fsid;