From f3a0592b37b83e56a7f47826f552b35a2c3b2fc9 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Fri, 14 Apr 2006 15:07:27 -0700 Subject: [PATCH] [ATM]: clip causes unregister hang If Classical IP over ATM module is loaded, its neighbor table gets populated when permanent neighbor entries are created; but these entries are not flushed when the device is removed. Since the entry never gets flushed the unregister of the network device never completes. This version of the patch also adds locking around the reference to the atm arp daemon to avoid races with events and daemon state changes. (Note: barrier() was never really safe) Bug-reference: http://bugzilla.kernel.org/show_bug.cgi?id=6295 Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/atm/clip.c | 42 +++++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 15 deletions(-) diff --git a/net/atm/clip.c b/net/atm/clip.c index 3ab4e7947bab..5841c30384a4 100644 --- a/net/atm/clip.c +++ b/net/atm/clip.c @@ -613,12 +613,19 @@ static int clip_create(int number) static int clip_device_event(struct notifier_block *this,unsigned long event, - void *dev) + void *arg) { + struct net_device *dev = arg; + + if (event == NETDEV_UNREGISTER) { + neigh_ifdown(&clip_tbl, dev); + return NOTIFY_DONE; + } + /* ignore non-CLIP devices */ - if (((struct net_device *) dev)->type != ARPHRD_ATM || - ((struct net_device *) dev)->hard_start_xmit != clip_start_xmit) + if (dev->type != ARPHRD_ATM || dev->hard_start_xmit != clip_start_xmit) return NOTIFY_DONE; + switch (event) { case NETDEV_UP: DPRINTK("clip_device_event NETDEV_UP\n"); @@ -686,14 +693,12 @@ static struct notifier_block clip_inet_notifier = { static void atmarpd_close(struct atm_vcc *vcc) { DPRINTK("atmarpd_close\n"); - atmarpd = NULL; /* assumed to be atomic */ - barrier(); - unregister_inetaddr_notifier(&clip_inet_notifier); - unregister_netdevice_notifier(&clip_dev_notifier); - if (skb_peek(&sk_atm(vcc)->sk_receive_queue)) - printk(KERN_ERR "atmarpd_close: closing with requests " - "pending\n"); + + rtnl_lock(); + atmarpd = NULL; skb_queue_purge(&sk_atm(vcc)->sk_receive_queue); + rtnl_unlock(); + DPRINTK("(done)\n"); module_put(THIS_MODULE); } @@ -714,7 +719,12 @@ static struct atm_dev atmarpd_dev = { static int atm_init_atmarp(struct atm_vcc *vcc) { - if (atmarpd) return -EADDRINUSE; + rtnl_lock(); + if (atmarpd) { + rtnl_unlock(); + return -EADDRINUSE; + } + if (start_timer) { start_timer = 0; init_timer(&idle_timer); @@ -731,10 +741,7 @@ static int atm_init_atmarp(struct atm_vcc *vcc) vcc->push = NULL; vcc->pop = NULL; /* crash */ vcc->push_oam = NULL; /* crash */ - if (register_netdevice_notifier(&clip_dev_notifier)) - printk(KERN_ERR "register_netdevice_notifier failed\n"); - if (register_inetaddr_notifier(&clip_inet_notifier)) - printk(KERN_ERR "register_inetaddr_notifier failed\n"); + rtnl_unlock(); return 0; } @@ -992,6 +999,8 @@ static int __init atm_clip_init(void) clip_tbl_hook = &clip_tbl; register_atm_ioctl(&clip_ioctl_ops); + register_netdevice_notifier(&clip_dev_notifier); + register_inetaddr_notifier(&clip_inet_notifier); #ifdef CONFIG_PROC_FS { @@ -1012,6 +1021,9 @@ static void __exit atm_clip_exit(void) remove_proc_entry("arp", atm_proc_root); + unregister_inetaddr_notifier(&clip_inet_notifier); + unregister_netdevice_notifier(&clip_dev_notifier); + deregister_atm_ioctl(&clip_ioctl_ops); /* First, stop the idle timer, so it stops banging -- 2.20.1