net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()

Le dimanche 05 décembre 2010 à 09:19 +0100, Eric Dumazet a écrit :

> Hmm..
>
> If somebody can explain why RTNL is held in arp_ioctl() (and therefore
> in arp_req_delete()), we might first remove RTNL use in arp_ioctl() so
> that your patch can be applied.
>
> Right now it is not good, because RTNL wont be necessarly held when you
> are going to call arp_invalidate() ?

While doing this analysis, I found a refcount bug in llc, I'll send a
patch for net-2.6

Meanwhile, here is the patch for net-next-2.6

Your patch then can be applied after mine.

Thanks

[PATCH] net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()

dev_getbyhwaddr() was called under RTNL.

Rename it to dev_getbyhwaddr_rcu() and change all its caller to now use
RCU locking instead of RTNL.

Change arp_ioctl() to use RCU instead of RTNL locking.

Note: this fix a dev refcount bug in llc

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a9ac5dc26e3c..d31bc3c94717 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1360,7 +1360,8 @@ static inline struct net_device *first_net_device(struct net *net)
 
 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(struct net *net, unsigned short type, char *hwaddr);
+extern struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
+                                              const char *hwaddr);
 extern struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type);
 extern struct net_device *__dev_getfirstbyhwtype(struct net *net, unsigned short type);
 extern void             dev_add_pack(struct packet_type *pt);