Date:	Tue, 25 Mar 2014 09:03:01 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Stephen Hemminger <stephen@...workplumber.org>,
	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: [PATCH net] ipv6: move DAD and addrconf_verify processing to workqueue

addrconf_join_solict and addrconf_join_anycast may cause actions which
need rtnl locked, especially on first address creation.

To get rtnl lock we need to push the code paths which depend on those
calls up to workqueues, specifically addrconf_verify and the DAD
processing.

Relevant backtrace:
[  541.030090] RTNL: assertion failed at net/core/dev.c (4496)
[  541.031143] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G           O 3.10.33-1-amd64-vyatta #1
[  541.031145] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
[  541.031146]  ffffffff8148a9f0 000000000000002f ffffffff813c98c1 ffff88007c4451f8
[  541.031148]  0000000000000000 0000000000000000 ffffffff813d3540 ffff88007fc03d18
[  541.031150]  0000880000000006 ffff88007c445000 ffffffffa0194160 0000000000000000
[  541.031152] Call Trace:
[  541.031153]  <IRQ>  [<ffffffff8148a9f0>] ? dump_stack+0xd/0x17
[  541.031180]  [<ffffffff813c98c1>] ? __dev_set_promiscuity+0x101/0x180
[  541.031183]  [<ffffffff813d3540>] ? __hw_addr_create_ex+0x60/0xc0
[  541.031185]  [<ffffffff813cfe1a>] ? __dev_set_rx_mode+0xaa/0xc0
[  541.031189]  [<ffffffff813d3a81>] ? __dev_mc_add+0x61/0x90
[  541.031198]  [<ffffffffa01dcf9c>] ? igmp6_group_added+0xfc/0x1a0 [ipv6]
[  541.031208]  [<ffffffff8111237b>] ? kmem_cache_alloc+0xcb/0xd0
[  541.031212]  [<ffffffffa01ddcd7>] ? ipv6_dev_mc_inc+0x267/0x300 [ipv6]
[  541.031216]  [<ffffffffa01c2fae>] ? addrconf_join_solict+0x2e/0x40 [ipv6]
[  541.031219]  [<ffffffffa01ba2e9>] ? ipv6_dev_ac_inc+0x159/0x1f0 [ipv6]
[  541.031223]  [<ffffffffa01c0772>] ? addrconf_join_anycast+0x92/0xa0 [ipv6]
[  541.031226]  [<ffffffffa01c311e>] ? __ipv6_ifa_notify+0x11e/0x1e0 [ipv6]
[  541.031229]  [<ffffffffa01c3213>] ? ipv6_ifa_notify+0x33/0x50 [ipv6]
[  541.031233]  [<ffffffffa01c36c8>] ? addrconf_dad_completed+0x28/0x100 [ipv6]
[  541.031241]  [<ffffffff81075c1d>] ? task_cputime+0x2d/0x50
[  541.031244]  [<ffffffffa01c38d6>] ? addrconf_dad_timer+0x136/0x150 [ipv6]
[  541.031247]  [<ffffffffa01c37a0>] ? addrconf_dad_completed+0x100/0x100 [ipv6]
[  541.031255]  [<ffffffff8105313a>] ? call_timer_fn.isra.22+0x2a/0x90
[  541.031258]  [<ffffffffa01c37a0>] ? addrconf_dad_completed+0x100/0x100 [ipv6]

Hunks and backtrace stolen from a patch by Stephen Hemminger.

Reported-by: Stephen Hemminger <stephen@...workplumber.org>
Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
 include/net/if_inet6.h |   3 +-
 net/ipv6/addrconf.c    | 146 +++++++++++++++++++++++++++++++++++++------------
 2 files changed, 114 insertions(+), 35 deletions(-)

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index 9650a3f..1cdcf9c 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -31,6 +31,7 @@
 #define IF_PREFIX_AUTOCONF	0x02
 
 enum {
+	INET6_IFADDR_STATE_PREDAD,
 	INET6_IFADDR_STATE_DAD,
 	INET6_IFADDR_STATE_POSTDAD,
 	INET6_IFADDR_STATE_UP,
@@ -58,7 +59,7 @@ struct inet6_ifaddr {
 	unsigned long		cstamp;	/* created timestamp */
 	unsigned long		tstamp; /* updated timestamp */
 
-	struct timer_list	dad_timer;
+	struct delayed_work	dad_work;
 
 	struct inet6_dev	*idev;
 	struct rt6_info		*rt;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 344e972..9d31dd1 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -133,9 +133,12 @@ static int ipv6_count_addresses(struct inet6_dev *idev);
 static struct hlist_head inet6_addr_lst[IN6_ADDR_HSIZE];
 static DEFINE_SPINLOCK(addrconf_hash_lock);
 
-static void addrconf_verify(unsigned long);
+static void addrconf_verify(void);
+static void addrconf_verify_rtnl(void);
+static void addrconf_verify_work(struct work_struct *);
 
-static DEFINE_TIMER(addr_chk_timer, addrconf_verify, 0, 0);
+static struct workqueue_struct *addrconf_wq;
+static DECLARE_DELAYED_WORK(addr_chk_work, addrconf_verify_work);
 static DEFINE_SPINLOCK(addrconf_verify_lock);
 
 static void addrconf_join_anycast(struct inet6_ifaddr *ifp);
@@ -151,7 +154,7 @@ static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
 						  u32 flags, u32 noflags);
 
 static void addrconf_dad_start(struct inet6_ifaddr *ifp);
-static void addrconf_dad_timer(unsigned long data);
+static void addrconf_dad_work(struct work_struct *w);
 static void addrconf_dad_completed(struct inet6_ifaddr *ifp);
 static void addrconf_dad_run(struct inet6_dev *idev);
 static void addrconf_rs_timer(unsigned long data);
@@ -247,9 +250,9 @@ static void addrconf_del_rs_timer(struct inet6_dev *idev)
 		__in6_dev_put(idev);
 }
 
-static void addrconf_del_dad_timer(struct inet6_ifaddr *ifp)
+static void addrconf_del_dad_work(struct inet6_ifaddr *ifp)
 {
-	if (del_timer(&ifp->dad_timer))
+	if (cancel_delayed_work(&ifp->dad_work))
 		__in6_ifa_put(ifp);
 }
 
@@ -261,12 +264,12 @@ static void addrconf_mod_rs_timer(struct inet6_dev *idev,
 	mod_timer(&idev->rs_timer, jiffies + when);
 }
 
-static void addrconf_mod_dad_timer(struct inet6_ifaddr *ifp,
+static void addrconf_mod_dad_work(struct inet6_ifaddr *ifp,
 				   unsigned long when)
 {
-	if (!timer_pending(&ifp->dad_timer))
+	if (!delayed_work_pending(&ifp->dad_work))
 		in6_ifa_hold(ifp);
-	mod_timer(&ifp->dad_timer, jiffies + when);
+	mod_delayed_work(addrconf_wq, &ifp->dad_work, when);
 }
 
 static int snmp6_alloc_dev(struct inet6_dev *idev)
@@ -751,7 +754,7 @@ void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp)
 
 	in6_dev_put(ifp->idev);
 
-	if (del_timer(&ifp->dad_timer))
+	if (cancel_delayed_work(&ifp->dad_work))
 		pr_notice("Timer is still running, when freeing ifa=%p\n", ifp);
 
 	if (ifp->state != INET6_IFADDR_STATE_DEAD) {
@@ -849,8 +852,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
 
 	spin_lock_init(&ifa->lock);
 	spin_lock_init(&ifa->state_lock);
-	setup_timer(&ifa->dad_timer, addrconf_dad_timer,
-		    (unsigned long)ifa);
+	INIT_DELAYED_WORK(&ifa->dad_work, addrconf_dad_work);
 	INIT_HLIST_NODE(&ifa->addr_lst);
 	ifa->scope = scope;
 	ifa->prefix_len = pfxlen;
@@ -1021,7 +1023,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
 
 	write_unlock_bh(&ifp->idev->lock);
 
-	addrconf_del_dad_timer(ifp);
+	addrconf_del_dad_work(ifp);
 
 	ipv6_ifa_notify(RTM_DELADDR, ifp);
 
@@ -1604,7 +1606,7 @@ static void addrconf_dad_stop(struct inet6_ifaddr *ifp, int dad_failed)
 {
 	if (ifp->flags&IFA_F_PERMANENT) {
 		spin_lock_bh(&ifp->lock);
-		addrconf_del_dad_timer(ifp);
+		addrconf_del_dad_work(ifp);
 		ifp->flags |= IFA_F_TENTATIVE;
 		if (dad_failed)
 			ifp->flags |= IFA_F_DADFAILED;
@@ -1680,6 +1682,8 @@ void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr)
 {
 	struct in6_addr maddr;
 
+	ASSERT_RTNL();
+
 	if (dev->flags&(IFF_LOOPBACK|IFF_NOARP))
 		return;
 
@@ -1691,6 +1695,8 @@ void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr)
 {
 	struct in6_addr maddr;
 
+	ASSERT_RTNL();
+
 	if (idev->dev->flags&(IFF_LOOPBACK|IFF_NOARP))
 		return;
 
@@ -1701,6 +1707,9 @@ void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr)
 static void addrconf_join_anycast(struct inet6_ifaddr *ifp)
 {
 	struct in6_addr addr;
+
+	ASSERT_RTNL();
+
 	if (ifp->prefix_len >= 127) /* RFC 6164 */
 		return;
 	ipv6_addr_prefix(&addr, &ifp->addr, ifp->prefix_len);
@@ -1712,6 +1721,9 @@ static void addrconf_join_anycast(struct inet6_ifaddr *ifp)
 static void addrconf_leave_anycast(struct inet6_ifaddr *ifp)
 {
 	struct in6_addr addr;
+
+	ASSERT_RTNL();
+
 	if (ifp->prefix_len >= 127) /* RFC 6164 */
 		return;
 	ipv6_addr_prefix(&addr, &ifp->addr, ifp->prefix_len);
@@ -2271,11 +2283,13 @@ ok:
 				return;
 			}
 
-			ifp->flags |= IFA_F_MANAGETEMPADDR;
 			update_lft = 0;
 			create = 1;
+			spin_lock_bh(&ifp->lock);
+			ifp->flags |= IFA_F_MANAGETEMPADDR;
 			ifp->cstamp = jiffies;
 			ifp->tokenized = tokenized;
+			spin_unlock_bh(&ifp->lock);
 			addrconf_dad_start(ifp);
 		}
 
@@ -2326,7 +2340,7 @@ ok:
 					 create, now);
 
 			in6_ifa_put(ifp);
-			addrconf_verify(0);
+			addrconf_verify();
 		}
 	}
 	inet6_prefix_notify(RTM_NEWPREFIX, in6_dev, pinfo);
@@ -2475,7 +2489,7 @@ static int inet6_addr_add(struct net *net, int ifindex,
 			manage_tempaddrs(idev, ifp, valid_lft, prefered_lft,
 					 true, jiffies);
 		in6_ifa_put(ifp);
-		addrconf_verify(0);
+		addrconf_verify_rtnl();
 		return 0;
 	}
 
@@ -3011,7 +3025,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 		hlist_for_each_entry_rcu(ifa, h, addr_lst) {
 			if (ifa->idev == idev) {
 				hlist_del_init_rcu(&ifa->addr_lst);
-				addrconf_del_dad_timer(ifa);
+				addrconf_del_dad_work(ifa);
 				goto restart;
 			}
 		}
@@ -3049,7 +3063,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 	while (!list_empty(&idev->addr_list)) {
 		ifa = list_first_entry(&idev->addr_list,
 				       struct inet6_ifaddr, if_list);
-		addrconf_del_dad_timer(ifa);
+		addrconf_del_dad_work(ifa);
 
 		list_del(&ifa->if_list);
 
@@ -3148,15 +3162,17 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
 		rand_num = prandom_u32() % (idev->cnf.rtr_solicit_delay ? : 1);
 
 	ifp->dad_probes = idev->cnf.dad_transmits;
-	addrconf_mod_dad_timer(ifp, rand_num);
+	addrconf_mod_dad_work(ifp, rand_num);
 }
 
-static void addrconf_dad_start(struct inet6_ifaddr *ifp)
+static void addrconf_dad_begin(struct inet6_ifaddr *ifp)
 {
 	struct inet6_dev *idev = ifp->idev;
 	struct net_device *dev = idev->dev;
 
+	rtnl_lock();
 	addrconf_join_solict(dev, &ifp->addr);
+	rtnl_unlock();
 
 	prandom_seed((__force u32) ifp->addr.s6_addr32[3]);
 
@@ -3203,11 +3219,42 @@ out:
 	read_unlock_bh(&idev->lock);
 }
 
-static void addrconf_dad_timer(unsigned long data)
+static void addrconf_dad_start(struct inet6_ifaddr *ifp)
+{
+	bool begin_dad = false;
+
+	spin_lock_bh(&ifp->state_lock);
+	if (ifp->state != INET6_IFADDR_STATE_DEAD) {
+		ifp->state = INET6_IFADDR_STATE_PREDAD;
+		begin_dad = true;
+	}
+	spin_unlock_bh(&ifp->state_lock);
+
+	if (begin_dad) {
+		in6_ifa_hold(ifp);
+		mod_delayed_work(addrconf_wq, &ifp->dad_work, 0);
+	}
+}
+
+static void addrconf_dad_work(struct work_struct *w)
 {
-	struct inet6_ifaddr *ifp = (struct inet6_ifaddr *) data;
+	struct inet6_ifaddr *ifp = container_of(to_delayed_work(w),
+						struct inet6_ifaddr,
+						dad_work);
 	struct inet6_dev *idev = ifp->idev;
 	struct in6_addr mcaddr;
+	bool begin_dad;
+
+	spin_lock_bh(&ifp->state_lock);
+	begin_dad = ifp->state == INET6_IFADDR_STATE_PREDAD;
+	if (begin_dad)
+		ifp->state = INET6_IFADDR_STATE_DAD;
+	spin_unlock_bh(&ifp->state_lock);
+
+	if (begin_dad) {
+		addrconf_dad_begin(ifp);
+		goto out;
+	}
 
 	if (!ifp->dad_probes && addrconf_dad_end(ifp))
 		goto out;
@@ -3240,8 +3287,8 @@ static void addrconf_dad_timer(unsigned long data)
 	}
 
 	ifp->dad_probes--;
-	addrconf_mod_dad_timer(ifp,
-			       NEIGH_VAR(ifp->idev->nd_parms, RETRANS_TIME));
+	addrconf_mod_dad_work(ifp,
+			      NEIGH_VAR(ifp->idev->nd_parms, RETRANS_TIME));
 	spin_unlock(&ifp->lock);
 	write_unlock(&idev->lock);
 
@@ -3276,13 +3323,15 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
 	struct in6_addr lladdr;
 	bool send_rs, send_mld;
 
-	addrconf_del_dad_timer(ifp);
+	addrconf_del_dad_work(ifp);
 
 	/*
 	 *	Configure the address for reception. Now it is valid.
 	 */
 
+	rtnl_lock();
 	ipv6_ifa_notify(RTM_NEWADDR, ifp);
+	rtnl_unlock();
 
 	/* If added prefix is link local and we are prepared to process
 	   router advertisements, start sending router solicitations.
@@ -3517,18 +3566,20 @@ int ipv6_chk_home_addr(struct net *net, const struct in6_addr *addr)
  *	Periodic address status verification
  */
 
-static void addrconf_verify(unsigned long foo)
+static void addrconf_verify_rtnl(void)
 {
 	unsigned long now, next, next_sec, next_sched;
 	struct inet6_ifaddr *ifp;
 	int i;
 
+	ASSERT_RTNL();
+
 	rcu_read_lock_bh();
 	spin_lock(&addrconf_verify_lock);
 	now = jiffies;
 	next = round_jiffies_up(now + ADDR_CHECK_FREQUENCY);
 
-	del_timer(&addr_chk_timer);
+	cancel_delayed_work(&addr_chk_work);
 
 	for (i = 0; i < IN6_ADDR_HSIZE; i++) {
 restart:
@@ -3629,12 +3680,23 @@ restart:
 	ADBG(KERN_DEBUG "now = %lu, schedule = %lu, rounded schedule = %lu => %lu\n",
 	      now, next, next_sec, next_sched);
 
-	addr_chk_timer.expires = next_sched;
-	add_timer(&addr_chk_timer);
+	mod_delayed_work(addrconf_wq, &addr_chk_work, next_sched - now);
 	spin_unlock(&addrconf_verify_lock);
 	rcu_read_unlock_bh();
 }
 
+static void addrconf_verify_work(struct work_struct *w)
+{
+	rtnl_lock();
+	addrconf_verify_rtnl();
+	rtnl_unlock();
+}
+
+static void addrconf_verify(void)
+{
+	mod_delayed_work(addrconf_wq, &addr_chk_work, 0);
+}
+
 static struct in6_addr *extract_addr(struct nlattr *addr, struct nlattr *local,
 				     struct in6_addr **peer_pfx)
 {
@@ -3691,6 +3753,8 @@ static int inet6_addr_modify(struct inet6_ifaddr *ifp, u32 ifa_flags,
 	bool was_managetempaddr;
 	bool had_prefixroute;
 
+	ASSERT_RTNL();
+
 	if (!valid_lft || (prefered_lft > valid_lft))
 		return -EINVAL;
 
@@ -3756,7 +3820,7 @@ static int inet6_addr_modify(struct inet6_ifaddr *ifp, u32 ifa_flags,
 				 !was_managetempaddr, jiffies);
 	}
 
-	addrconf_verify(0);
+	addrconf_verify();
 
 	return 0;
 }
@@ -4386,6 +4450,8 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
 	bool update_rs = false;
 	struct in6_addr ll_addr;
 
+	ASSERT_RTNL();
+
 	if (token == NULL)
 		return -EINVAL;
 	if (ipv6_addr_any(token))
@@ -4434,7 +4500,7 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
 	}
 
 	write_unlock_bh(&idev->lock);
-	addrconf_verify(0);
+	addrconf_verify();
 	return 0;
 }
 
@@ -4636,6 +4702,9 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
 {
 	struct net *net = dev_net(ifp->idev->dev);
 
+	if (!event)
+		ASSERT_RTNL();
+
 	inet6_ifa_notify(event ? : RTM_NEWADDR, ifp);
 
 	switch (event) {
@@ -5244,6 +5313,12 @@ int __init addrconf_init(void)
 	if (err < 0)
 		goto out_addrlabel;
 
+	addrconf_wq = create_workqueue("ipv6_addrconf");
+	if (!addrconf_wq) {
+		err = -ENOMEM;
+		goto out_nowq;
+	}
+
 	/* The addrconf netdev notifier requires that loopback_dev
 	 * has it's ipv6 private information allocated and setup
 	 * before it can bring up and give link-local addresses
@@ -5274,7 +5349,7 @@ int __init addrconf_init(void)
 
 	register_netdevice_notifier(&ipv6_dev_notf);
 
-	addrconf_verify(0);
+	addrconf_verify();
 
 	rtnl_af_register(&inet6_ops);
 
@@ -5302,6 +5377,8 @@ errout:
 	rtnl_af_unregister(&inet6_ops);
 	unregister_netdevice_notifier(&ipv6_dev_notf);
 errlo:
+	destroy_workqueue(addrconf_wq);
+out_nowq:
 	unregister_pernet_subsys(&addrconf_ops);
 out_addrlabel:
 	ipv6_addr_label_cleanup();
@@ -5337,7 +5414,8 @@ void addrconf_cleanup(void)
 	for (i = 0; i < IN6_ADDR_HSIZE; i++)
 		WARN_ON(!hlist_empty(&inet6_addr_lst[i]));
 	spin_unlock_bh(&addrconf_hash_lock);
-
-	del_timer(&addr_chk_timer);
+	cancel_delayed_work(&addr_chk_work);
 	rtnl_unlock();
+
+	destroy_workqueue(addrconf_wq);
 }
-- 
1.8.5.3

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