From: Apollon Oikonomopoulos <apollon@noc•grnet.gr>
To: netdev@vger•kernel.org
Subject: [PATCH] X.25: decrement netdev reference counts on unload
Date: Tue, 7 Dec 2010 21:43:30 +0200 [thread overview]
Message-ID: <20101207194330.GA22608@noc.grnet.gr> (raw)
Hello,
We came across this bug when we accidentally loaded and unloaded the x25
kernel module on a host with KVM virtual machines. All subsequent
attempts to stop a KVM instance resulted in the KVM process entering D
state. Reproducing this behaviour can be done in the following way:
1. modprobe x25
2. tunctl && ifconfig tap0 up
3. rmmod x25
4. tunctl -d tap0 (hangs)
A patch follows - we don't use X.25 ourselves so I'm not sure it won't
panic someone's system.
Regards,
Apollon
PS: I am not subscribed to the list, so please copy any replies to my
address. Thanks!
----
x25 does not decrement the network device reference counts on module unload.
Thus unregistering any pre-existing interface after unloading the x25 module
hangs and results in
unregister_netdevice: waiting for tap0 to become free. Usage count = 1
This patch decrements the reference counts of all interfaces in x25_link_free,
the way it is already done in x25_link_device_down for NETDEV_DOWN events.
Signed-off-by: Apollon Oikonomopoulos <apollon@noc•grnet.gr>
---
net/x25/x25_link.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c
index 73e7b95..b25c646 100644
--- a/net/x25/x25_link.c
+++ b/net/x25/x25_link.c
@@ -394,6 +394,7 @@ void __exit x25_link_free(void)
list_for_each_safe(entry, tmp, &x25_neigh_list) {
nb = list_entry(entry, struct x25_neigh, node);
__x25_remove_neigh(nb);
+ dev_put(nb->dev);
}
write_unlock_bh(&x25_neigh_list_lock);
}
--
1.7.1
next reply other threads:[~2010-12-07 19:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-07 19:43 Apollon Oikonomopoulos [this message]
2010-12-07 22:48 ` [PATCH] X.25: decrement netdev reference counts on unload Andrew Hendry
2010-12-08 18:55 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20101207194330.GA22608@noc.grnet.gr \
--to=apollon@noc$(echo .)grnet.gr \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox