diff options
| author | Ben Hutchings <bhutchings@solarflare.com> | 2012-08-14 08:54:51 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-02 10:29:35 -0700 |
| commit | 84a2d3c44cce71152f3555af83bafea6ec5ef23c (patch) | |
| tree | fb069dbaa2fe6244cf4a4eaa9cbcdfdc57d22771 /net/ipv6 | |
| parent | c8cca9d90b953a0a2b5d0edab789f5c52ae983f5 (diff) | |
ipv6: addrconf: Avoid calling netdevice notifiers with RCU read-side lock
[ Upstream commit 4acd4945cd1e1f92b20d14e349c6c6a52acbd42d ]
Cong Wang reports that lockdep detected suspicious RCU usage while
enabling IPV6 forwarding:
[ 1123.310275] ===============================
[ 1123.442202] [ INFO: suspicious RCU usage. ]
[ 1123.558207] 3.6.0-rc1+ #109 Not tainted
[ 1123.665204] -------------------------------
[ 1123.768254] include/linux/rcupdate.h:430 Illegal context switch in RCU read-side critical section!
[ 1123.992320]
[ 1123.992320] other info that might help us debug this:
[ 1123.992320]
[ 1124.307382]
[ 1124.307382] rcu_scheduler_active = 1, debug_locks = 0
[ 1124.522220] 2 locks held by sysctl/5710:
[ 1124.648364] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff81768498>] rtnl_trylock+0x15/0x17
[ 1124.882211] #1: (rcu_read_lock){.+.+.+}, at: [<ffffffff81871df8>] rcu_lock_acquire+0x0/0x29
[ 1125.085209]
[ 1125.085209] stack backtrace:
[ 1125.332213] Pid: 5710, comm: sysctl Not tainted 3.6.0-rc1+ #109
[ 1125.441291] Call Trace:
[ 1125.545281] [<ffffffff8109d915>] lockdep_rcu_suspicious+0x109/0x112
[ 1125.667212] [<ffffffff8107c240>] rcu_preempt_sleep_check+0x45/0x47
[ 1125.781838] [<ffffffff8107c260>] __might_sleep+0x1e/0x19b
[...]
[ 1127.445223] [<ffffffff81757ac5>] call_netdevice_notifiers+0x4a/0x4f
[...]
[ 1127.772188] [<ffffffff8175e125>] dev_disable_lro+0x32/0x6b
[ 1127.885174] [<ffffffff81872d26>] dev_forward_change+0x30/0xcb
[ 1128.013214] [<ffffffff818738c4>] addrconf_forward_change+0x85/0xc5
[...]
addrconf_forward_change() uses RCU iteration over the netdev list,
which is unnecessary since it already holds the RTNL lock. We also
cannot reasonably require netdevice notifier functions not to sleep.
Reported-by: Cong Wang <amwang@redhat.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/addrconf.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 7d5cb975cc6f..2c69eca4b61a 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -493,8 +493,7 @@ static void addrconf_forward_change(struct net *net, __s32 newf) struct net_device *dev; struct inet6_dev *idev; - rcu_read_lock(); - for_each_netdev_rcu(net, dev) { + for_each_netdev(net, dev) { idev = __in6_dev_get(dev); if (idev) { int changed = (!idev->cnf.forwarding) ^ (!newf); @@ -503,7 +502,6 @@ static void addrconf_forward_change(struct net *net, __s32 newf) dev_forward_change(idev); } } - rcu_read_unlock(); } static int addrconf_fixup_forwarding(struct ctl_table *table, int *p, int newf) |