From 3ef208a71f18b128e318294af3f7ee8081fe0ac1 Mon Sep 17 00:00:00 2001 From: Amerigo Wang Date: Sat, 29 Jun 2013 21:30:49 +0800 Subject: ipv6,mcast: always hold idev->lock before mca_lock [ Upstream commit 8965779d2c0e6ab246c82a405236b1fb2adae6b2, with some bits from commit b7b1bfce0bb68bd8f6e62a28295922785cc63781 ("ipv6: split duplicate address detection and router solicitation timer") to get the __ipv6_get_lladdr() used by this patch. ] dingtianhong reported the following deadlock detected by lockdep: ====================================================== [ INFO: possible circular locking dependency detected ] 3.4.24.05-0.1-default #1 Not tainted ------------------------------------------------------- ksoftirqd/0/3 is trying to acquire lock: (&ndev->lock){+.+...}, at: [] ipv6_get_lladdr+0x74/0x120 but task is already holding lock: (&mc->mca_lock){+.+...}, at: [] mld_send_report+0x40/0x150 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mc->mca_lock){+.+...}: [] validate_chain+0x637/0x730 [] __lock_acquire+0x2f7/0x500 [] lock_acquire+0x114/0x150 [] rt_spin_lock+0x4a/0x60 [] igmp6_group_added+0x3b/0x120 [] ipv6_mc_up+0x38/0x60 [] ipv6_find_idev+0x3d/0x80 [] addrconf_notify+0x3d5/0x4b0 [] notifier_call_chain+0x3f/0x80 [] raw_notifier_call_chain+0x11/0x20 [] call_netdevice_notifiers+0x32/0x60 [] __dev_notify_flags+0x34/0x80 [] dev_change_flags+0x40/0x70 [] do_setlink+0x237/0x8a0 [] rtnl_newlink+0x3ec/0x600 [] rtnetlink_rcv_msg+0x160/0x310 [] netlink_rcv_skb+0x89/0xb0 [] rtnetlink_rcv+0x27/0x40 [] netlink_unicast+0x140/0x180 [] netlink_sendmsg+0x33e/0x380 [] sock_sendmsg+0x112/0x130 [] __sys_sendmsg+0x44e/0x460 [] sys_sendmsg+0x44/0x70 [] system_call_fastpath+0x16/0x1b -> #0 (&ndev->lock){+.+...}: [] check_prev_add+0x3de/0x440 [] validate_chain+0x637/0x730 [] __lock_acquire+0x2f7/0x500 [] lock_acquire+0x114/0x150 [] rt_read_lock+0x42/0x60 [] ipv6_get_lladdr+0x74/0x120 [] mld_newpack+0xb6/0x160 [] add_grhead+0xab/0xc0 [] add_grec+0x3ab/0x460 [] mld_send_report+0x5a/0x150 [] igmp6_timer_handler+0x4e/0xb0 [] call_timer_fn+0xca/0x1d0 [] run_timer_softirq+0x1df/0x2e0 [] handle_pending_softirqs+0xf7/0x1f0 [] __do_softirq_common+0x7b/0xf0 [] __thread_do_softirq+0x1af/0x210 [] run_ksoftirqd+0xe1/0x1f0 [] kthread+0xae/0xc0 [] kernel_thread_helper+0x4/0x10 actually we can just hold idev->lock before taking pmc->mca_lock, and avoid taking idev->lock again when iterating idev->addr_list, since the upper callers of mld_newpack() already take read_lock_bh(&idev->lock). Reported-by: dingtianhong Cc: dingtianhong Cc: Hideaki YOSHIFUJI Cc: David S. Miller Cc: Hannes Frederic Sowa Tested-by: Ding Tianhong Tested-by: Chen Weilong Signed-off-by: Cong Wang Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/addrconf.c | 28 ++++++++++++++++++---------- net/ipv6/mcast.c | 18 ++++++++++-------- 2 files changed, 28 insertions(+), 18 deletions(-) (limited to 'net') diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 1217f2e375e..d427f1bae2e 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1233,6 +1233,23 @@ try_nextdev: } EXPORT_SYMBOL(ipv6_dev_get_saddr); +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) { @@ -1242,17 +1259,8 @@ 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(); diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index b2869cab209..6a4ab24a5d6 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -1334,8 +1334,9 @@ mld_scount(struct ifmcaddr6 *pmc, int type, int gdeleted, int sdeleted) return scount; } -static struct sk_buff *mld_newpack(struct net_device *dev, int size) +static struct sk_buff *mld_newpack(struct inet6_dev *idev, int size) { + struct net_device *dev = idev->dev; struct net *net = dev_net(dev); struct sock *sk = net->ipv6.igmp_sk; struct sk_buff *skb; @@ -1360,7 +1361,7 @@ static struct sk_buff *mld_newpack(struct net_device *dev, int size) skb_reserve(skb, hlen); - if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) { + if (__ipv6_get_lladdr(idev, &addr_buf, IFA_F_TENTATIVE)) { /* : * use unspecified address as the source address * when a valid link-local address is not available. @@ -1456,7 +1457,7 @@ static struct sk_buff *add_grhead(struct sk_buff *skb, struct ifmcaddr6 *pmc, struct mld2_grec *pgr; if (!skb) - skb = mld_newpack(dev, dev->mtu); + skb = mld_newpack(pmc->idev, dev->mtu); if (!skb) return NULL; pgr = (struct mld2_grec *)skb_put(skb, sizeof(struct mld2_grec)); @@ -1476,7 +1477,8 @@ static struct sk_buff *add_grhead(struct sk_buff *skb, struct ifmcaddr6 *pmc, static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, int type, int gdeleted, int sdeleted) { - struct net_device *dev = pmc->idev->dev; + struct inet6_dev *idev = pmc->idev; + struct net_device *dev = idev->dev; struct mld2_report *pmr; struct mld2_grec *pgr = NULL; struct ip6_sf_list *psf, *psf_next, *psf_prev, **psf_list; @@ -1505,7 +1507,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, AVAILABLE(skb) < grec_size(pmc, type, gdeleted, sdeleted)) { if (skb) mld_sendpack(skb); - skb = mld_newpack(dev, dev->mtu); + skb = mld_newpack(idev, dev->mtu); } } first = 1; @@ -1532,7 +1534,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, pgr->grec_nsrcs = htons(scount); if (skb) mld_sendpack(skb); - skb = mld_newpack(dev, dev->mtu); + skb = mld_newpack(idev, dev->mtu); first = 1; scount = 0; } @@ -1587,8 +1589,8 @@ static void mld_send_report(struct inet6_dev *idev, struct ifmcaddr6 *pmc) struct sk_buff *skb = NULL; int type; + read_lock_bh(&idev->lock); if (!pmc) { - read_lock_bh(&idev->lock); for (pmc=idev->mc_list; pmc; pmc=pmc->next) { if (pmc->mca_flags & MAF_NOREPORT) continue; @@ -1600,7 +1602,6 @@ static void mld_send_report(struct inet6_dev *idev, struct ifmcaddr6 *pmc) skb = add_grec(skb, pmc, type, 0, 0); spin_unlock_bh(&pmc->mca_lock); } - read_unlock_bh(&idev->lock); } else { spin_lock_bh(&pmc->mca_lock); if (pmc->mca_sfcount[MCAST_EXCLUDE]) @@ -1610,6 +1611,7 @@ static void mld_send_report(struct inet6_dev *idev, struct ifmcaddr6 *pmc) skb = add_grec(skb, pmc, type, 0, 0); spin_unlock_bh(&pmc->mca_lock); } + read_unlock_bh(&idev->lock); if (skb) mld_sendpack(skb); } -- cgit v1.2.3-18-g5258