diff options
| author | Nicolas Schichan <nschichan@freebox.fr> | 2013-06-26 17:23:42 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-06-26 13:42:54 -0700 |
| commit | 5dbe7c178d3f0a4634f088d9e729f1909b9ddcd1 (patch) | |
| tree | 8945b6c5125b57cee5f36e903fc995e58664a639 /include | |
| parent | 6d446ec32f169c6a5d9bc90684a8082a6cbe90f6 (diff) | |
net: fix kernel deadlock with interface rename and netdev name retrieval.
When the kernel (compiled with CONFIG_PREEMPT=n) is performing the
rename of a network interface, it can end up waiting for a workqueue
to complete. If userland is able to invoke a SIOCGIFNAME ioctl or a
SO_BINDTODEVICE getsockopt in between, the kernel will deadlock due to
the fact that read_secklock_begin() will spin forever waiting for the
writer process (the one doing the interface rename) to update the
devnet_rename_seq sequence.
This patch fixes the problem by adding a helper (netdev_get_name())
and using it in the code handling the SIOCGIFNAME ioctl and
SO_BINDTODEVICE setsockopt.
The netdev_get_name() helper uses raw_seqcount_begin() to avoid
spinning forever, waiting for devnet_rename_seq->sequence to become
even. cond_resched() is used in the contended case, before retrying
the access to give the writer process a chance to finish.
The use of raw_seqcount_begin() will incur some unneeded work in the
reader process in the contended case, but this is better than
deadlocking the system.
Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/netdevice.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 60584b185a0..96e4c21e15e 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1695,6 +1695,7 @@ extern int init_dummy_netdev(struct net_device *dev); extern struct net_device *dev_get_by_index(struct net *net, int ifindex); extern struct net_device *__dev_get_by_index(struct net *net, int ifindex); extern struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex); +extern int netdev_get_name(struct net *net, char *name, int ifindex); extern int dev_restart(struct net_device *dev); #ifdef CONFIG_NETPOLL_TRAP extern int netpoll_trap(void); |