Module Name: src
Committed By: dholland
Date: Sat Jan 9 07:52:38 UTC 2016
Modified Files:
src/sys/kern: kern_fork.c sys_process.c
Log Message:
When doing an unlock/relock dance to avoid lock inversion, it's important
to relock the lock you unlocked. Otherwise the lock you unlocked won't
walk the walk, not by a long chalk, and you'll end up getting mocked.
>From Mateusz Guzik of FreeBSD via freenode.
XXX: pullup-6 and -7
To generate a diff of this commit:
cvs rdiff -u -r1.194 -r1.195 src/sys/kern/kern_fork.c
cvs rdiff -u -r1.166 -r1.167 src/sys/kern/sys_process.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/kern/kern_fork.c
diff -u src/sys/kern/kern_fork.c:1.194 src/sys/kern/kern_fork.c:1.195
--- src/sys/kern/kern_fork.c:1.194 Fri Oct 2 16:54:15 2015
+++ src/sys/kern/kern_fork.c Sat Jan 9 07:52:38 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_fork.c,v 1.194 2015/10/02 16:54:15 christos Exp $ */
+/* $NetBSD: kern_fork.c,v 1.195 2016/01/09 07:52:38 dholland Exp $ */
/*-
* Copyright (c) 1999, 2001, 2004, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.194 2015/10/02 16:54:15 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.195 2016/01/09 07:52:38 dholland Exp $");
#include "opt_ktrace.h"
#include "opt_dtrace.h"
@@ -486,6 +486,7 @@ fork1(struct lwp *l1, int flags, int exi
if (!mutex_tryenter(parent1->p_lock)) {
mutex_exit(p2->p_lock);
mutex_enter(parent1->p_lock);
+ mutex_enter(p2->p_lock);
}
} else if (parent1->p_lock > p2->p_lock) {
mutex_enter(parent1->p_lock);
Index: src/sys/kern/sys_process.c
diff -u src/sys/kern/sys_process.c:1.166 src/sys/kern/sys_process.c:1.167
--- src/sys/kern/sys_process.c:1.166 Thu Jul 2 03:47:54 2015
+++ src/sys/kern/sys_process.c Sat Jan 9 07:52:38 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: sys_process.c,v 1.166 2015/07/02 03:47:54 christos Exp $ */
+/* $NetBSD: sys_process.c,v 1.167 2016/01/09 07:52:38 dholland Exp $ */
/*-
* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -118,7 +118,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.166 2015/07/02 03:47:54 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.167 2016/01/09 07:52:38 dholland Exp $");
#include "opt_ptrace.h"
#include "opt_ktrace.h"
@@ -782,6 +782,7 @@ sys_ptrace(struct lwp *l, const struct s
if (!mutex_tryenter(parent->p_lock)) {
mutex_exit(t->p_lock);
mutex_enter(parent->p_lock);
+ mutex_enter(t->p_lock);
}
} else if (parent->p_lock > t->p_lock) {
mutex_enter(parent->p_lock);
