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netpoll: fix a rtnl lock assertion failure

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v4: hold rtnl lock for the whole netpoll_setup()
v3: remove the comment
v2: use RCU read lock

This patch fixes the following warning:

[   72.013864] RTNL: assertion failed at net/core/dev.c (4955)
[   72.017758] Pid: 668, comm: netpoll-prep-v6 Not tainted 3.8.0-rc1+ #474
[   72.019582] Call Trace:
[   72.020295]  [<ffffffff8176653d>] netdev_master_upper_dev_get+0x35/0x58
[   72.022545]  [<ffffffff81784edd>] netpoll_setup+0x61/0x340
[   72.024846]  [<ffffffff815d837e>] store_enabled+0x82/0xc3
[   72.027466]  [<ffffffff815d7e51>] netconsole_target_attr_store+0x35/0x37
[   72.029348]  [<ffffffff811c3479>] configfs_write_file+0xe2/0x10c
[   72.030959]  [<ffffffff8115d239>] vfs_write+0xaf/0xf6
[   72.032359]  [<ffffffff81978a05>] ? sysret_check+0x22/0x5d
[   72.033824]  [<ffffffff8115d453>] sys_write+0x5c/0x84
[   72.035328]  [<ffffffff819789d9>] system_call_fastpath+0x16/0x1b

In case of other races, hold rtnl lock for the entire netpoll_setup() function.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2013-01-14 23:34:06 +00:00 committed by David S. Miller
parent 7db11f7596
commit f92d318023
1 changed files with 10 additions and 14 deletions
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24
net/core/netpoll.c
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@ -1048,11 +1048,13 @@ int netpoll_setup(struct netpoll *np)
struct in_device *in_dev;
int err;
rtnl_lock();
if (np->dev_name)
ndev = dev_get_by_name(&init_net, np->dev_name);
ndev = __dev_get_by_name(&init_net, np->dev_name);
if (!ndev) {
np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
return -ENODEV;
err = -ENODEV;
goto unlock;
}
if (netdev_master_upper_dev_get(ndev)) {
@ -1066,15 +1068,14 @@ int netpoll_setup(struct netpoll *np)
np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
rtnl_lock();
err = dev_open(ndev);
rtnl_unlock();
if (err) {
np_err(np, "failed to open %s\n", ndev->name);
goto put;
}
rtnl_unlock();
atleast = jiffies + HZ/10;
atmost = jiffies + carrier_timeout * HZ;
while (!netif_carrier_ok(ndev)) {
@ -1094,16 +1095,14 @@ int netpoll_setup(struct netpoll *np)
np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n");
msleep(4000);
}
rtnl_lock();
}
if (!np->local_ip.ip) {
if (!np->ipv6) {
rcu_read_lock();
in_dev = __in_dev_get_rcu(ndev);
in_dev = __in_dev_get_rtnl(ndev);
if (!in_dev || !in_dev->ifa_list) {
rcu_read_unlock();
np_err(np, "no IP address for %s, aborting\n",
np->dev_name);
err = -EDESTADDRREQ;
@ -1111,14 +1110,12 @@ int netpoll_setup(struct netpoll *np)
}
np->local_ip.ip = in_dev->ifa_list->ifa_local;
rcu_read_unlock();
np_info(np, "local IP %pI4\n", &np->local_ip.ip);
} else {
#if IS_ENABLED(CONFIG_IPV6)
struct inet6_dev *idev;
err = -EDESTADDRREQ;
rcu_read_lock();
idev = __in6_dev_get(ndev);
if (idev) {
struct inet6_ifaddr *ifp;
@ -1133,7 +1130,6 @@ int netpoll_setup(struct netpoll *np)
}
read_unlock_bh(&idev->lock);
}
rcu_read_unlock();
if (err) {
np_err(np, "no IPv6 address for %s, aborting\n",
np->dev_name);
@ -1151,17 +1147,17 @@ int netpoll_setup(struct netpoll *np)
/* fill up the skb queue */
refill_skbs();
rtnl_lock();
err = __netpoll_setup(np, ndev, GFP_KERNEL);
rtnl_unlock();
if (err)
goto put;
rtnl_unlock();
return 0;
put:
dev_put(ndev);
unlock:
rtnl_unlock();
return err;
}
EXPORT_SYMBOL(netpoll_setup);