[ 3.8.y.z extended stable ] Patch "ipv6, mcast: always hold idev->lock before mca_lock" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Fri Jul 26 00:24:07 UTC 2013
This is a note to let you know that I have just added a patch titled
ipv6,mcast: always hold idev->lock before mca_lock
to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue
This patch is scheduled to be released in version 3.8.13.6.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From c6ec836c2e35f8ef44640021b13d937238f195e3 Mon Sep 17 00:00:00 2001
From: Amerigo Wang <amwang at redhat.com>
Date: Sat, 29 Jun 2013 21:30:49 +0800
Subject: ipv6,mcast: always hold idev->lock before mca_lock
commit 8965779d2c0e6ab246c82a405236b1fb2adae6b2 upstream.
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: [<ffffffff8147f804>] ipv6_get_lladdr+0x74/0x120
but task is already holding lock:
(&mc->mca_lock){+.+...}, at: [<ffffffff8149d130>] 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){+.+...}:
[<ffffffff810a8027>] validate_chain+0x637/0x730
[<ffffffff810a8417>] __lock_acquire+0x2f7/0x500
[<ffffffff810a8734>] lock_acquire+0x114/0x150
[<ffffffff814f691a>] rt_spin_lock+0x4a/0x60
[<ffffffff8149e4bb>] igmp6_group_added+0x3b/0x120
[<ffffffff8149e5d8>] ipv6_mc_up+0x38/0x60
[<ffffffff81480a4d>] ipv6_find_idev+0x3d/0x80
[<ffffffff81483175>] addrconf_notify+0x3d5/0x4b0
[<ffffffff814fae3f>] notifier_call_chain+0x3f/0x80
[<ffffffff81073471>] raw_notifier_call_chain+0x11/0x20
[<ffffffff813d8722>] call_netdevice_notifiers+0x32/0x60
[<ffffffff813d92d4>] __dev_notify_flags+0x34/0x80
[<ffffffff813d9360>] dev_change_flags+0x40/0x70
[<ffffffff813ea627>] do_setlink+0x237/0x8a0
[<ffffffff813ebb6c>] rtnl_newlink+0x3ec/0x600
[<ffffffff813eb4d0>] rtnetlink_rcv_msg+0x160/0x310
[<ffffffff814040b9>] netlink_rcv_skb+0x89/0xb0
[<ffffffff813eb357>] rtnetlink_rcv+0x27/0x40
[<ffffffff81403e20>] netlink_unicast+0x140/0x180
[<ffffffff81404a9e>] netlink_sendmsg+0x33e/0x380
[<ffffffff813c4252>] sock_sendmsg+0x112/0x130
[<ffffffff813c537e>] __sys_sendmsg+0x44e/0x460
[<ffffffff813c5544>] sys_sendmsg+0x44/0x70
[<ffffffff814feab9>] system_call_fastpath+0x16/0x1b
-> #0 (&ndev->lock){+.+...}:
[<ffffffff810a798e>] check_prev_add+0x3de/0x440
[<ffffffff810a8027>] validate_chain+0x637/0x730
[<ffffffff810a8417>] __lock_acquire+0x2f7/0x500
[<ffffffff810a8734>] lock_acquire+0x114/0x150
[<ffffffff814f6c82>] rt_read_lock+0x42/0x60
[<ffffffff8147f804>] ipv6_get_lladdr+0x74/0x120
[<ffffffff8149b036>] mld_newpack+0xb6/0x160
[<ffffffff8149b18b>] add_grhead+0xab/0xc0
[<ffffffff8149d03b>] add_grec+0x3ab/0x460
[<ffffffff8149d14a>] mld_send_report+0x5a/0x150
[<ffffffff8149f99e>] igmp6_timer_handler+0x4e/0xb0
[<ffffffff8105705a>] call_timer_fn+0xca/0x1d0
[<ffffffff81057b9f>] run_timer_softirq+0x1df/0x2e0
[<ffffffff8104e8c7>] handle_pending_softirqs+0xf7/0x1f0
[<ffffffff8104ea3b>] __do_softirq_common+0x7b/0xf0
[<ffffffff8104f07f>] __thread_do_softirq+0x1af/0x210
[<ffffffff8104f1c1>] run_ksoftirqd+0xe1/0x1f0
[<ffffffff8106c7de>] kthread+0xae/0xc0
[<ffffffff814fff74>] 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 <dingtianhong at huawei.com>
Cc: dingtianhong <dingtianhong at huawei.com>
Cc: Hideaki YOSHIFUJI <yoshfuji at linux-ipv6.org>
Cc: David S. Miller <davem at davemloft.net>
Cc: Hannes Frederic Sowa <hannes at stressinduktion.org>
Tested-by: Ding Tianhong <dingtianhong at huawei.com>
Tested-by: Chen Weilong <chenweilong at huawei.com>
Signed-off-by: Cong Wang <amwang at redhat.com>
Acked-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.5, based on the davem's backport to 3.4:
- get __ipv6_get_lladdr() from commit b7b1bfce0bb68bd8f6e62a28295922785cc63781
("ipv6: split duplicate address detection and router solicitation timer") ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
include/net/addrconf.h | 3 +++
net/ipv6/addrconf.c | 28 ++++++++++++++++++----------
net/ipv6/mcast.c | 18 ++++++++++--------
3 files changed, 31 insertions(+), 18 deletions(-)
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 594abec..697d911 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -82,6 +82,9 @@ extern int ipv6_dev_get_saddr(struct net *net,
const struct in6_addr *daddr,
unsigned int srcprefs,
struct in6_addr *saddr);
+extern int __ipv6_get_lladdr(struct inet6_dev *idev,
+ struct in6_addr *addr,
+ unsigned char banned_flags);
extern int ipv6_get_lladdr(struct net_device *dev,
struct in6_addr *addr,
unsigned char banned_flags);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index c6987a9..7b54fff 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1370,6 +1370,23 @@ 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)
{
@@ -1379,17 +1396,8 @@ 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 28dfa5f..79fa628 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1340,8 +1340,9 @@ 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;
@@ -1366,7 +1367,7 @@ 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)) {
/* <draft-ietf-magma-mld-source-05.txt>:
* use unspecified address as the source address
* when a valid link-local address is not available.
@@ -1462,7 +1463,7 @@ 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));
@@ -1482,7 +1483,8 @@ 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;
@@ -1511,7 +1513,7 @@ 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;
@@ -1538,7 +1540,7 @@ 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;
}
@@ -1593,8 +1595,8 @@ 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;
@@ -1606,7 +1608,6 @@ 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])
@@ -1616,6 +1617,7 @@ 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);
}
--
1.8.1.2
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