Module Name: src
Committed By: snj
Date: Sun Apr 8 06:10:24 UTC 2018
Modified Files:
src/sys/miscfs/procfs [netbsd-8]: procfs_vnops.c
Log Message:
Pull up following revision(s) (requested by hannken in ticket #702):
sys/miscfs/procfs/procfs_vnops.c: 1.203
Lock the target cwdi and take an additional reference to the
vnode we are interested in to prevent it from disappearing
before getcwd_common().
Should fix PR kern/53096 (netbsd-8 crash on heavy disk I/O)
To generate a diff of this commit:
cvs rdiff -u -r1.197 -r1.197.2.1 src/sys/miscfs/procfs/procfs_vnops.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/miscfs/procfs/procfs_vnops.c
diff -u src/sys/miscfs/procfs/procfs_vnops.c:1.197 src/sys/miscfs/procfs/procfs_vnops.c:1.197.2.1
--- src/sys/miscfs/procfs/procfs_vnops.c:1.197 Fri May 26 14:21:01 2017
+++ src/sys/miscfs/procfs/procfs_vnops.c Sun Apr 8 06:10:24 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: procfs_vnops.c,v 1.197 2017/05/26 14:21:01 riastradh Exp $ */
+/* $NetBSD: procfs_vnops.c,v 1.197.2.1 2018/04/08 06:10:24 snj Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -105,7 +105,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: procfs_vnops.c,v 1.197 2017/05/26 14:21:01 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: procfs_vnops.c,v 1.197.2.1 2018/04/08 06:10:24 snj Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -543,11 +543,10 @@ procfs_symlink(void *v)
}
/*
- * Works out the path to (and vnode of) the target process's current
+ * Works out the path to the target process's current
* working directory or chroot. If the caller is in a chroot and
* can't "reach" the target's cwd or root (or some other error
- * occurs), a "/" is returned for the path and a NULL pointer is
- * returned for the vnode.
+ * occurs), a "/" is returned for the path.
*/
static void
procfs_dir(pfstype t, struct lwp *caller, struct proc *target, char **bpp,
@@ -557,12 +556,12 @@ procfs_dir(pfstype t, struct lwp *caller
struct vnode *vp, *rvp;
char *bp;
- cwdi = caller->l_proc->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
-
- rvp = cwdi->cwdi_rdir;
- bp = bpp ? *bpp : NULL;
-
+ /*
+ * Lock target cwdi and take a reference to the vnode
+ * we are interested in to prevent it from disappearing
+ * before getcwd_common() below.
+ */
+ rw_enter(&target->p_cwdi->cwdi_lock, RW_READER);
switch (t) {
case PFScwd:
vp = target->p_cwdi->cwdi_cdir;
@@ -574,9 +573,18 @@ procfs_dir(pfstype t, struct lwp *caller
vp = target->p_textvp;
break;
default:
- rw_exit(&cwdi->cwdi_lock);
+ rw_exit(&target->p_cwdi->cwdi_lock);
return;
}
+ if (vp != NULL)
+ vref(vp);
+ rw_exit(&target->p_cwdi->cwdi_lock);
+
+ cwdi = caller->l_proc->p_cwdi;
+ rw_enter(&cwdi->cwdi_lock, RW_READER);
+
+ rvp = cwdi->cwdi_rdir;
+ bp = bpp ? *bpp : NULL;
/*
* XXX: this horrible kludge avoids locking panics when
@@ -587,6 +595,7 @@ procfs_dir(pfstype t, struct lwp *caller
*--bp = '/';
*bpp = bp;
}
+ vrele(vp);
rw_exit(&cwdi->cwdi_lock);
return;
}
@@ -595,7 +604,6 @@ procfs_dir(pfstype t, struct lwp *caller
rvp = rootvnode;
if (vp == NULL || getcwd_common(vp, rvp, bp ? &bp : NULL, path,
len / 2, 0, caller) != 0) {
- vp = NULL;
if (bpp) {
/*
if (t == PFSexe) {
@@ -611,6 +619,8 @@ procfs_dir(pfstype t, struct lwp *caller
if (bpp)
*bpp = bp;
+ if (vp != NULL)
+ vrele(vp);
rw_exit(&cwdi->cwdi_lock);
}
