From f3d9832e56c48e4ca50bab0457e21bcaade4536d Mon Sep 17 00:00:00 2001 From: David Ahern Date: Wed, 18 Oct 2017 09:56:52 -0700 Subject: ipv6: addrconf: cleanup locking in ipv6_add_addr ipv6_add_addr is called in process context with rtnl lock held (e.g., manual config of an address) or during softirq processing (e.g., autoconf and address from a router advertisement). Currently, ipv6_add_addr calls rcu_read_lock_bh shortly after entry and does not call unlock until exit, minus the call around the address validator notifier. Similarly, addrconf_hash_lock is taken after the validator notifier and held until exit. This forces the allocation of inet6_ifaddr to always be atomic. Refactor ipv6_add_addr as follows: 1. add an input boolean to discriminate the call path (process context or softirq). This new flag controls whether the alloc can be done with GFP_KERNEL or GFP_ATOMIC. 2. Move the rcu_read_lock_bh and unlock calls only around functions that do rcu updates. 3. Remove the in6_dev_hold and put added by 3ad7d2468f79f ("Ipvlan should return an error when an address is already in use."). This was done presumably because rcu_read_unlock_bh needs to be called before calling the validator. Since rcu_read_lock is not needed before the validator runs revert the hold and put added by 3ad7d2468f79f and only do the hold when setting ifp->idev. 4. move duplicate address check and insertion of new address in the global address hash into a helper. The helper is called after an ifa is allocated and filled in. This allows the ifa for manually configured addresses to be done with GFP_KERNEL and reduces the overall amount of time with rcu_read_lock held and hash table spinlock held. Signed-off-by: David Ahern Signed-off-by: David S. Miller --- net/ipv6/addrconf.c | 104 ++++++++++++++++++++++++++++++---------------------- 1 file changed, 60 insertions(+), 44 deletions(-) (limited to 'net/ipv6/addrconf.c') diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 4603aa488f4f..a8d202b1b919 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -957,18 +957,43 @@ static u32 inet6_addr_hash(const struct in6_addr *addr) return hash_32(ipv6_addr_hash(addr), IN6_ADDR_HSIZE_SHIFT); } +static int ipv6_add_addr_hash(struct net_device *dev, struct inet6_ifaddr *ifa) +{ + unsigned int hash; + int err = 0; + + spin_lock(&addrconf_hash_lock); + + /* Ignore adding duplicate addresses on an interface */ + if (ipv6_chk_same_addr(dev_net(dev), &ifa->addr, dev)) { + ADBG("ipv6_add_addr: already assigned\n"); + err = -EEXIST; + goto out; + } + + /* Add to big hash table */ + hash = inet6_addr_hash(&ifa->addr); + hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]); + +out: + spin_unlock(&addrconf_hash_lock); + + return err; +} + /* On success it returns ifp with increased reference count */ static struct inet6_ifaddr * ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, const struct in6_addr *peer_addr, int pfxlen, - int scope, u32 flags, u32 valid_lft, u32 prefered_lft) + int scope, u32 flags, u32 valid_lft, u32 prefered_lft, + bool can_block) { + gfp_t gfp_flags = can_block ? GFP_KERNEL : GFP_ATOMIC; struct net *net = dev_net(idev->dev); struct inet6_ifaddr *ifa = NULL; - struct rt6_info *rt; + struct rt6_info *rt = NULL; struct in6_validator_info i6vi; - unsigned int hash; int err = 0; int addr_type = ipv6_addr_type(addr); @@ -978,42 +1003,24 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, addr_type & IPV6_ADDR_LOOPBACK)) return ERR_PTR(-EADDRNOTAVAIL); - rcu_read_lock_bh(); - - in6_dev_hold(idev); - if (idev->dead) { err = -ENODEV; /*XXX*/ - goto out2; + goto out; } if (idev->cnf.disable_ipv6) { err = -EACCES; - goto out2; + goto out; } i6vi.i6vi_addr = *addr; i6vi.i6vi_dev = idev; - rcu_read_unlock_bh(); - err = inet6addr_validator_notifier_call_chain(NETDEV_UP, &i6vi); - - rcu_read_lock_bh(); err = notifier_to_errno(err); - if (err) - goto out2; - - spin_lock(&addrconf_hash_lock); - - /* Ignore adding duplicate addresses on an interface */ - if (ipv6_chk_same_addr(dev_net(idev->dev), addr, idev->dev)) { - ADBG("ipv6_add_addr: already assigned\n"); - err = -EEXIST; + if (err < 0) goto out; - } - - ifa = kzalloc(sizeof(struct inet6_ifaddr), GFP_ATOMIC); + ifa = kzalloc(sizeof(*ifa), gfp_flags); if (!ifa) { ADBG("ipv6_add_addr: malloc failed\n"); err = -ENOBUFS; @@ -1023,6 +1030,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, rt = addrconf_dst_alloc(idev, addr, false); if (IS_ERR(rt)) { err = PTR_ERR(rt); + rt = NULL; goto out; } @@ -1053,16 +1061,21 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, ifa->rt = rt; ifa->idev = idev; + in6_dev_hold(idev); + /* For caller */ refcount_set(&ifa->refcnt, 1); - /* Add to big hash table */ - hash = inet6_addr_hash(addr); + rcu_read_lock_bh(); - hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]); - spin_unlock(&addrconf_hash_lock); + err = ipv6_add_addr_hash(idev->dev, ifa); + if (err < 0) { + rcu_read_unlock_bh(); + goto out; + } write_lock(&idev->lock); + /* Add to inet6_dev unicast addr list. */ ipv6_link_dev_addr(idev, ifa); @@ -1073,21 +1086,23 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, in6_ifa_hold(ifa); write_unlock(&idev->lock); -out2: + rcu_read_unlock_bh(); - if (likely(err == 0)) - inet6addr_notifier_call_chain(NETDEV_UP, ifa); - else { - kfree(ifa); - in6_dev_put(idev); + inet6addr_notifier_call_chain(NETDEV_UP, ifa); +out: + if (unlikely(err < 0)) { + if (rt) + ip6_rt_put(rt); + if (ifa) { + if (ifa->idev) + in6_dev_put(ifa->idev); + kfree(ifa); + } ifa = ERR_PTR(err); } return ifa; -out: - spin_unlock(&addrconf_hash_lock); - goto out2; } enum cleanup_prefix_rt_t { @@ -1334,7 +1349,7 @@ retry: ift = ipv6_add_addr(idev, &addr, NULL, tmp_plen, ipv6_addr_scope(&addr), addr_flags, - tmp_valid_lft, tmp_prefered_lft); + tmp_valid_lft, tmp_prefered_lft, true); if (IS_ERR(ift)) { in6_ifa_put(ifp); in6_dev_put(idev); @@ -2018,7 +2033,7 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp) ifp2 = ipv6_add_addr(idev, &new_addr, NULL, pfxlen, scope, flags, valid_lft, - preferred_lft); + preferred_lft, false); if (IS_ERR(ifp2)) goto lock_errdad; @@ -2476,7 +2491,7 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev, pinfo->prefix_len, addr_type&IPV6_ADDR_SCOPE_MASK, addr_flags, valid_lft, - prefered_lft); + prefered_lft, false); if (IS_ERR_OR_NULL(ifp)) return -1; @@ -2845,7 +2860,7 @@ static int inet6_addr_add(struct net *net, int ifindex, } ifp = ipv6_add_addr(idev, pfx, peer_pfx, plen, scope, ifa_flags, - valid_lft, prefered_lft); + valid_lft, prefered_lft, true); if (!IS_ERR(ifp)) { if (!(ifa_flags & IFA_F_NOPREFIXROUTE)) { @@ -2960,7 +2975,8 @@ static void add_addr(struct inet6_dev *idev, const struct in6_addr *addr, ifp = ipv6_add_addr(idev, addr, NULL, plen, scope, IFA_F_PERMANENT, - INFINITY_LIFE_TIME, INFINITY_LIFE_TIME); + INFINITY_LIFE_TIME, INFINITY_LIFE_TIME, + true); if (!IS_ERR(ifp)) { spin_lock_bh(&ifp->lock); ifp->flags &= ~IFA_F_TENTATIVE; @@ -3060,7 +3076,7 @@ void addrconf_add_linklocal(struct inet6_dev *idev, #endif ifp = ipv6_add_addr(idev, addr, NULL, 64, IFA_LINK, addr_flags, - INFINITY_LIFE_TIME, INFINITY_LIFE_TIME); + INFINITY_LIFE_TIME, INFINITY_LIFE_TIME, true); if (!IS_ERR(ifp)) { addrconf_prefix_route(&ifp->addr, ifp->prefix_len, idev->dev, 0, 0); addrconf_dad_start(ifp); -- cgit