Hi lkml-members,
I recently had a problem with appletalk. After starting atalkd on a TAP
interface and stopping it later, unregister_netdevice() just stated
| unregister_netdevice: waiting for tap0 to become free. Usage count = -1
So I assume there is a problem in the appletalk code, but I didn't try
reproducing that on other systems so far.
I changed my kernel to "correct" a negative refcnt to 0 and that kind
of fixes the problem. I'm not sure whether this could break anything,
but certainly waiting for a device to become free is no use when there
is a negative number of users, so I think it would be better to allow
the system to shut down cleanly in this case.
Here's m suggestion:
#v+
--- linux-2.6.11-orig/net/core/dev.c 2005-03-02 08:38:09.000000000 +0100
+++ linux-2.6.11/net/core/dev.c 2005-04-09 16:44:42.000000000 +0200
@@ -2876,7 +2876,7 @@
unsigned long rebroadcast_time, warning_time;
rebroadcast_time = warning_time = jiffies;
- while (atomic_read(&dev->refcnt) != 0) {
+ while (atomic_read(&dev->refcnt) > 0) {
if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
rtnl_shlock();
@@ -2910,6 +2910,13 @@
warning_time = jiffies;
}
}
+ if (atomic_read(&dev->refcnt) != 0) {
+ printk(KERN_ERR "unregister_netdevice: "
+ "%s has negative refcnt (%d). "
+ "This should never happen! Setting refcnt to 0.\n",
+ dev->name, atomic_read(&dev->refcnt));
+ atomic_set(&dev->refcnt, 0);
+ }
}
/* The sequence is:
#v-
Greets, Felix
PS: Please note I'm not subscribed to lkml and CC me in replies, thanks.
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