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Subject[PATCH 57/75] ipv6,mcast: always hold idev->lock before mca_lock
Date
3.8.13.6 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Amerigo Wang <amwang@redhat.com>

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@huawei.com>
Cc: dingtianhong <dingtianhong@huawei.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Tested-by: Ding Tianhong <dingtianhong@huawei.com>
Tested-by: Chen Weilong <chenweilong@huawei.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@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@canonical.com>

Signed-off-by: Kamal Mostafa <kamal@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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