Grrrr. Fix a really lame bug that I tripped over while testing my miibus

stuff: unregister_methods() is horribly broken. The idea, if I'm not mistaken,
is that the refcount on a method is decremented, and only when it reaches
zero is the method freed. However desc->method is set to NULL unconditionally
regardless of the refcount, which means the method pointer is trashed the
first time the method is deallocated. The obvious detrimental effect is
that memory is leaked. The not so obvious effect is that when you call
unregister_method() the second time on the same method, you get a NULL
pointer dereference and a panic.

Now I can successfully unload network device drivers and the miibus module
without crashing the system.

*sigh*

1 files changed, 2 insertions, 2 deletions

diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index 3044ada..f7fda58 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -23,7 +23,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: subr_bus.c,v 1.34 1999/08/11 22:05:17 peter Exp $
+ *	$Id: subr_bus.c,v 1.35 1999/08/11 22:55:39 peter Exp $
  */
 
 #include <sys/param.h>
@@ -159,8 +159,8 @@ unregister_method(struct device_op_desc *desc)
     if (m->refs == 0) {
 	LIST_REMOVE(m, link);
 	free(m, M_DEVBUF);
+    	desc->method = 0;
     }
-    desc->method = 0;
 }
 
 static int error_method(void)