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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-01-26 18:08:02 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-01-27 15:02:56 -0800 |
| commit | ccf434380d1a67df2dcb9113206b77d0cb0a1cef (patch) | |
| tree | 1e1a36691f42ed7448f27f71a9ca9445e88ab5f1 | |
| parent | 065825402c058f4a123ddc53dbbe864cc5caaf64 (diff) | |
| download | linux-ccf434380d1a67df2dcb9113206b77d0cb0a1cef.tar.gz linux-ccf434380d1a67df2dcb9113206b77d0cb0a1cef.tar.bz2 linux-ccf434380d1a67df2dcb9113206b77d0cb0a1cef.zip | |
net: fix dev_seq_next()
Commit c6d14c84566d (net: Introduce for_each_netdev_rcu() iterator)
added a race in dev_seq_next().
The rcu_dereference() call should be done _before_ testing the end of
list, or we might return a wrong net_device if a concurrent thread
changes net_device list under us.
Note : discovered thanks to a sparse warning :
net/core/dev.c:3919:9: error: incompatible types in comparison expression
(different address spaces)
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/netdevice.h | 9 | ||||
| -rw-r--r-- | net/core/dev.c | 11 |
2 files changed, 15 insertions, 5 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 8858422c5c5d..c7d707452228 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1447,7 +1447,7 @@ static inline struct net_device *next_net_device_rcu(struct net_device *dev) struct net *net; net = dev_net(dev); - lh = rcu_dereference(dev->dev_list.next); + lh = rcu_dereference(list_next_rcu(&dev->dev_list)); return lh == &net->dev_base_head ? NULL : net_device_entry(lh); } @@ -1457,6 +1457,13 @@ static inline struct net_device *first_net_device(struct net *net) net_device_entry(net->dev_base_head.next); } +static inline struct net_device *first_net_device_rcu(struct net *net) +{ + struct list_head *lh = rcu_dereference(list_next_rcu(&net->dev_base_head)); + + return lh == &net->dev_base_head ? NULL : net_device_entry(lh); +} + extern int netdev_boot_setup_check(struct net_device *dev); extern unsigned long netdev_boot_base(const char *prefix, int unit); extern struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type, diff --git a/net/core/dev.c b/net/core/dev.c index 1b4c07fe295f..ddd5df2b61d4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4051,12 +4051,15 @@ void *dev_seq_start(struct seq_file *seq, loff_t *pos) void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos) { - struct net_device *dev = (v == SEQ_START_TOKEN) ? - first_net_device(seq_file_net(seq)) : - next_net_device((struct net_device *)v); + struct net_device *dev = v; + + if (v == SEQ_START_TOKEN) + dev = first_net_device_rcu(seq_file_net(seq)); + else + dev = next_net_device_rcu(dev); ++*pos; - return rcu_dereference(dev); + return dev; } void dev_seq_stop(struct seq_file *seq, void *v) |