ipv6: split duplicate address detection and router solicitation timer

This patch splits the timers for duplicate address detection and router
solicitations apart. The router solicitations timer goes into inet6_dev
and the dad timer stays in inet6_ifaddr.

The reason behind this patch is to reduce the number of unneeded router
solicitations send out by the host if additional link-local addresses
are created. Currently we send out RS for every link-local address on
an interface.

If the RS timer fires we pick a source address with ipv6_get_lladdr. This
change could hurt people adding additional link-local addresses and
specifying these addresses in the radvd clients section because we
no longer guarantee that we use every ll address as source address in
router solicitations.

Cc: Flavio Leitner <fleitner@redhat.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: David Stevens <dlstevens@us.ibm.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reviewed-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 91 insertions, 73 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 90788a1c6bbc..c06bc76280b2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -253,37 +253,32 @@ static inline bool addrconf_qdisc_ok(const struct net_device *dev)
         return !qdisc_tx_is_noop(dev);
 }
 
-static void addrconf_del_timer(struct inet6_ifaddr *ifp)
+static void addrconf_del_rs_timer(struct inet6_dev *idev)
 {
-        if (del_timer(&ifp->timer))
+        if (del_timer(&idev->rs_timer))
+                __in6_dev_put(idev);
+}
+
+static void addrconf_del_dad_timer(struct inet6_ifaddr *ifp)
+{
+        if (del_timer(&ifp->dad_timer))
                 __in6_ifa_put(ifp);
 }
 
-enum addrconf_timer_t {
-        AC_NONE,
-        AC_DAD,
-        AC_RS,
-};
+static void addrconf_mod_rs_timer(struct inet6_dev *idev,
+                                  unsigned long when)
+{
+        if (!timer_pending(&idev->rs_timer))
+                in6_dev_hold(idev);
+        mod_timer(&idev->rs_timer, jiffies + when);
+}
 
-static void addrconf_mod_timer(struct inet6_ifaddr *ifp,
-                               enum addrconf_timer_t what,
-                               unsigned long when)
+static void addrconf_mod_dad_timer(struct inet6_ifaddr *ifp,
+                                   unsigned long when)
 {
-        if (!del_timer(&ifp->timer))
+        if (!timer_pending(&ifp->dad_timer))
                 in6_ifa_hold(ifp);
-
-        switch (what) {
-        case AC_DAD:
-                ifp->timer.function = addrconf_dad_timer;
-                break;
-        case AC_RS:
-                ifp->timer.function = addrconf_rs_timer;
-                break;
-        default:
-                break;
-        }
-        ifp->timer.expires = jiffies + when;
-        add_timer(&ifp->timer);
+        mod_timer(&ifp->dad_timer, jiffies + when);
 }
 
 static int snmp6_alloc_dev(struct inet6_dev *idev)
@@ -326,6 +321,7 @@ void in6_dev_finish_destroy(struct inet6_dev *idev)
 
         WARN_ON(!list_empty(&idev->addr_list));
         WARN_ON(idev->mc_list != NULL);
+        WARN_ON(timer_pending(&idev->rs_timer));
 
 #ifdef NET_REFCNT_DEBUG
         pr_debug("%s: %s\n", __func__, dev ? dev->name : "NIL");
@@ -357,7 +353,8 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
         rwlock_init(&ndev->lock);
         ndev->dev = dev;
         INIT_LIST_HEAD(&ndev->addr_list);
-
+        setup_timer(&ndev->rs_timer, addrconf_rs_timer,
+                    (unsigned long)ndev);
         memcpy(&ndev->cnf, dev_net(dev)->ipv6.devconf_dflt, sizeof(ndev->cnf));
         ndev->cnf.mtu6 = dev->mtu;
         ndev->cnf.sysctl = NULL;
@@ -776,7 +773,7 @@ void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp)
 
         in6_dev_put(ifp->idev);
 
-        if (del_timer(&ifp->timer))
+        if (del_timer(&ifp->dad_timer))
                 pr_notice("Timer is still running, when freeing ifa=%p\n", ifp);
 
         if (ifp->state != INET6_IFADDR_STATE_DEAD) {
@@ -869,9 +866,9 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
 
         spin_lock_init(&ifa->lock);
         spin_lock_init(&ifa->state_lock);
-        init_timer(&ifa->timer);
+        setup_timer(&ifa->dad_timer, addrconf_dad_timer,
+                    (unsigned long)ifa);
         INIT_HLIST_NODE(&ifa->addr_lst);
-        ifa->timer.data = (unsigned long) ifa;
         ifa->scope = scope;
         ifa->prefix_len = pfxlen;
         ifa->flags = flags | IFA_F_TENTATIVE;
@@ -994,7 +991,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
         }
         write_unlock_bh(&idev->lock);
 
-        addrconf_del_timer(ifp);
+        addrconf_del_dad_timer(ifp);
 
         ipv6_ifa_notify(RTM_DELADDR, ifp);
 
@@ -1447,6 +1444,23 @@ try_nextdev:
 }
 EXPORT_SYMBOL(ipv6_dev_get_saddr);
 
+static int __ipv6_get_lladdr(struct inet6_dev *idev, struct in6_addr *addr,
+                             unsigned char banned_flags)
+{
+        struct inet6_ifaddr *ifp;
+        int err = -EADDRNOTAVAIL;
+
+        list_for_each_entry(ifp, &idev->addr_list, if_list) {
+                if (ifp->scope == IFA_LINK &&
+                    !(ifp->flags & banned_flags)) {
+                        *addr = ifp->addr;
+                        err = 0;
+                        break;
+                }
+        }
+        return err;
+}
+
 int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr,
                     unsigned char banned_flags)
 {
@@ -1456,17 +1470,8 @@ int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr,
         rcu_read_lock();
         idev = __in6_dev_get(dev);
         if (idev) {
-                struct inet6_ifaddr *ifp;
-
                 read_lock_bh(&idev->lock);
-                list_for_each_entry(ifp, &idev->addr_list, if_list) {
-                        if (ifp->scope == IFA_LINK &&
-                            !(ifp->flags & banned_flags)) {
-                                *addr = ifp->addr;
-                                err = 0;
-                                break;
-                        }
-                }
+                err = __ipv6_get_lladdr(idev, addr, banned_flags);
                 read_unlock_bh(&idev->lock);
         }
         rcu_read_unlock();
@@ -1580,7 +1585,7 @@ 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_timer(ifp);
+                addrconf_del_dad_timer(ifp);
                 ifp->flags |= IFA_F_TENTATIVE;
                 if (dad_failed)
                         ifp->flags |= IFA_F_DADFAILED;
@@ -3036,7 +3041,7 @@ 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_timer(ifa);
+                                addrconf_del_dad_timer(ifa);
                                 goto restart;
                         }
                 }
@@ -3045,6 +3050,8 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
         write_lock_bh(&idev->lock);
 
+        addrconf_del_rs_timer(idev);
+
         /* Step 2: clear flags for stateless addrconf */
         if (!how)
                 idev->if_flags &= ~(IF_RS_SENT|IF_RA_RCVD|IF_READY);
@@ -3074,7 +3081,7 @@ 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_timer(ifa);
+                addrconf_del_dad_timer(ifa);
 
                 list_del(&ifa->if_list);
 
@@ -3116,10 +3123,10 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
 static void addrconf_rs_timer(unsigned long data)
 {
-        struct inet6_ifaddr *ifp = (struct inet6_ifaddr *) data;
-        struct inet6_dev *idev = ifp->idev;
+        struct inet6_dev *idev = (struct inet6_dev *)data;
+        struct in6_addr lladdr;
 
-        read_lock(&idev->lock);
+        write_lock(&idev->lock);
         if (idev->dead || !(idev->if_flags & IF_READY))
                 goto out;
 
@@ -3130,18 +3137,19 @@ static void addrconf_rs_timer(unsigned long data)
         if (idev->if_flags & IF_RA_RCVD)
                 goto out;
 
-        spin_lock(&ifp->lock);
-        if (ifp->probes++ < idev->cnf.rtr_solicits) {
-                /* The wait after the last probe can be shorter */
-                addrconf_mod_timer(ifp, AC_RS,
-                                   (ifp->probes == idev->cnf.rtr_solicits) ?
-                                   idev->cnf.rtr_solicit_delay :
-                                   idev->cnf.rtr_solicit_interval);
-                spin_unlock(&ifp->lock);
+        if (idev->rs_probes++ < idev->cnf.rtr_solicits) {
+                if (!__ipv6_get_lladdr(idev, &lladdr, IFA_F_TENTATIVE))
+                        ndisc_send_rs(idev->dev, &lladdr,
+                                      &in6addr_linklocal_allrouters);
+                else
+                        goto out;
 
-                ndisc_send_rs(idev->dev, &ifp->addr, &in6addr_linklocal_allrouters);
+                /* The wait after the last probe can be shorter */
+                addrconf_mod_rs_timer(idev, (idev->rs_probes ==
+                                             idev->cnf.rtr_solicits) ?
+                                      idev->cnf.rtr_solicit_delay :
+                                      idev->cnf.rtr_solicit_interval);
         } else {
-                spin_unlock(&ifp->lock);
                 /*
                  * Note: we do not support deprecated "all on-link"
                  * assumption any longer.
@@ -3150,8 +3158,8 @@ static void addrconf_rs_timer(unsigned long data)
         }
 
 out:
-        read_unlock(&idev->lock);
-        in6_ifa_put(ifp);
+        write_unlock(&idev->lock);
+        in6_dev_put(idev);
 }
 
 /*
@@ -3167,8 +3175,8 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
         else
                 rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
 
-        ifp->probes = idev->cnf.dad_transmits;
-        addrconf_mod_timer(ifp, AC_DAD, rand_num);
+        ifp->dad_probes = idev->cnf.dad_transmits;
+        addrconf_mod_dad_timer(ifp, rand_num);
 }
 
 static void addrconf_dad_start(struct inet6_ifaddr *ifp)
@@ -3229,40 +3237,40 @@ static void addrconf_dad_timer(unsigned long data)
         struct inet6_dev *idev = ifp->idev;
         struct in6_addr mcaddr;
 
-        if (!ifp->probes && addrconf_dad_end(ifp))
+        if (!ifp->dad_probes && addrconf_dad_end(ifp))
                 goto out;
 
-        read_lock(&idev->lock);
+        write_lock(&idev->lock);
         if (idev->dead || !(idev->if_flags & IF_READY)) {
-                read_unlock(&idev->lock);
+                write_unlock(&idev->lock);
                 goto out;
         }
 
         spin_lock(&ifp->lock);
         if (ifp->state == INET6_IFADDR_STATE_DEAD) {
                 spin_unlock(&ifp->lock);
-                read_unlock(&idev->lock);
+                write_unlock(&idev->lock);
                 goto out;
         }
 
-        if (ifp->probes == 0) {
+        if (ifp->dad_probes == 0) {
                 /*
                  * DAD was successful
                  */
 
                 ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC|IFA_F_DADFAILED);
                 spin_unlock(&ifp->lock);
-                read_unlock(&idev->lock);
+                write_unlock(&idev->lock);
 
                 addrconf_dad_completed(ifp);
 
                 goto out;
         }
 
-        ifp->probes--;
-        addrconf_mod_timer(ifp, AC_DAD, ifp->idev->nd_parms->retrans_time);
+        ifp->dad_probes--;
+        addrconf_mod_dad_timer(ifp, ifp->idev->nd_parms->retrans_time);
         spin_unlock(&ifp->lock);
-        read_unlock(&idev->lock);
+        write_unlock(&idev->lock);
 
         /* send a neighbour solicitation for our addr */
         addrconf_addr_solict_mult(&ifp->addr, &mcaddr);
@@ -3274,6 +3282,9 @@ out:
 static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
 {
         struct net_device *dev = ifp->idev->dev;
+        struct in6_addr lladdr;
+
+        addrconf_del_dad_timer(ifp);
 
         /*
          *      Configure the address for reception. Now it is valid.
@@ -3294,13 +3305,20 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
                  *      [...] as part of DAD [...] there is no need
                  *      to delay again before sending the first RS
                  */
-                ndisc_send_rs(ifp->idev->dev, &ifp->addr, &in6addr_linklocal_allrouters);
+                if (!ipv6_get_lladdr(dev, &lladdr, IFA_F_TENTATIVE))
+                        ndisc_send_rs(dev, &lladdr,
+                                      &in6addr_linklocal_allrouters);
+                else
+                        return;
 
-                spin_lock_bh(&ifp->lock);
-                ifp->probes = 1;
+                write_lock_bh(&ifp->idev->lock);
+                spin_lock(&ifp->lock);
+                ifp->idev->rs_probes = 1;
                 ifp->idev->if_flags |= IF_RS_SENT;
-                addrconf_mod_timer(ifp, AC_RS, ifp->idev->cnf.rtr_solicit_interval);
-                spin_unlock_bh(&ifp->lock);
+                addrconf_mod_rs_timer(ifp->idev,
+                                      ifp->idev->cnf.rtr_solicit_interval);
+                spin_unlock(&ifp->lock);
+                write_unlock_bh(&ifp->idev->lock);
         }
 }