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, 3 insertions, 3 deletions

diff --git a/net/ieee802154/af_ieee802154.c b/net/ieee802154/af_ieee802154.c
index 93c91b633a56..6df6ecf49708 100644
--- a/net/ieee802154/af_ieee802154.c
+++ b/net/ieee802154/af_ieee802154.c
@@ -52,11 +52,11 @@ struct net_device *ieee802154_get_dev(struct net *net,
 
         switch (addr->addr_type) {
         case IEEE802154_ADDR_LONG:
-                rtnl_lock();
-                dev = dev_getbyhwaddr(net, ARPHRD_IEEE802154, addr->hwaddr);
+                rcu_read_lock();
+                dev = dev_getbyhwaddr_rcu(net, ARPHRD_IEEE802154, addr->hwaddr);
                 if (dev)
                         dev_hold(dev);
-                rtnl_unlock();
+                rcu_read_unlock();
                 break;
         case IEEE802154_ADDR_SHORT:
                 if (addr->pan_id == 0xffff ||