[src/trunk]: src/sys/dev Take fss_device_lock first when closing a fss device.

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

details:   https://anonhg.NetBSD.org/src/rev/912ebd3d08c1
branches:  trunk
changeset: 784704:912ebd3d08c1
user:      hannken <hannken%NetBSD.org@localhost>
date:      Wed Feb 06 09:29:46 2013 +0000

description:
Take fss_device_lock first when closing a fss device.

Fixes PR kern/47514 (Multiple dump -X triggers kernel panic in fss_ioctl)

diffstat:

 sys/dev/fss.c |  11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diffs (46 lines):

diff -r 79c573fa8c94 -r 912ebd3d08c1 sys/dev/fss.c
--- a/sys/dev/fss.c     Wed Feb 06 09:05:01 2013 +0000
+++ b/sys/dev/fss.c     Wed Feb 06 09:29:46 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fss.c,v 1.83 2012/07/28 16:14:17 hannken Exp $ */
+/*     $NetBSD: fss.c,v 1.84 2013/02/06 09:29:46 hannken Exp $ */
 
 /*-
  * Copyright (c) 2003 The NetBSD Foundation, Inc.
@@ -36,7 +36,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.83 2012/07/28 16:14:17 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.84 2013/02/06 09:29:46 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -223,11 +223,13 @@
        mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN);
        error = 0;
 
+       mutex_enter(&fss_device_lock);
 restart:
        mutex_enter(&sc->sc_slock);
        if ((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) != mflag) {
                sc->sc_flags &= ~mflag;
                mutex_exit(&sc->sc_slock);
+               mutex_exit(&fss_device_lock);
                return 0;
        }
        if ((sc->sc_flags & FSS_ACTIVE) != 0 &&
@@ -239,12 +241,9 @@
        }
        if ((sc->sc_flags & FSS_ACTIVE) != 0) {
                mutex_exit(&sc->sc_slock);
+               mutex_exit(&fss_device_lock);
                return error;
        }
-       if (! mutex_tryenter(&fss_device_lock)) {
-               mutex_exit(&sc->sc_slock);
-               goto restart;
-       }
 
        KASSERT((sc->sc_flags & FSS_ACTIVE) == 0);
        KASSERT((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) == mflag);