Messages in this thread | | | Date | Thu, 09 Dec 2010 15:33:23 +0800 | From | Cong Wang <> | Subject | Re: [v3 PATCH 1/2] bonding: sync netpoll code with bridge |
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On 12/08/10 21:57, Neil Horman wrote: > On Wed, Dec 08, 2010 at 02:52:08AM -0500, Amerigo Wang wrote: >> - bond_for_each_slave(bond, slave, i) { >> - if ((slave->dev->priv_flags& IFF_DISABLE_NETPOLL) || >> - !slave->dev->netdev_ops->ndo_poll_controller) >> - ret = false; >> + np = kmalloc(sizeof(*np), GFP_KERNEL); >> + err = -ENOMEM; >> + if (!np) >> + goto out; >> + >> + np->dev = slave->dev; >> + err = __netpoll_setup(np); > Setting up our own netpoll instance on each slave worries me a bit. The > implication here is that, by doing so, some frames will get entirely processed > by the slave. Most notably arp frames. That means anything that gets queued up > to the arp_tx queue in __netpoll_rx will get processed during that poll event, > and responded to with the mac of the slave device, rather than with the mac of > the bond device, which isn't always what you want. I think if you go with this > route, you'll need to add code to netpoll_poll_dev, right before the call to > service_arp_queue, to check if IFF_SLAVE is set in priv_flags, and move the list > to the master device, or some such.
Good point! Will fix it.
> > It also seems like you'll want to zero out the other fields in the netpoll > structure. Leaving garbage in them will be bad. Most notably here I'm looking > at the rx_hook field. If its non-null we're going to add a bogus pointer to the > rx_np list and call off into space at some point. >
Ouch! I remember I really used kzalloc() here, don't know why kmalloc() gets into the final patch. Odd, I need to double check the patch. :-/
<...> >> +static void __bond_netpoll_cleanup(struct bonding *bond) >> +{ >> struct slave *slave; >> int i; >> >> - bond_for_each_slave(bond, slave, i) { >> - if (slave->dev&& IS_UP(slave->dev)) >> - netpoll_poll_dev(slave->dev); >> - } >> + bond_for_each_slave(bond, slave, i) >> + if (slave->dev) > Why are you checking slave->dev here? If the dev pointer has been set to NULL > here it would seem we're not holding on to dev long enough. If we enabled > netpoll with a dev pointer and lost it somewhere along the way, we're going to > leak that struct netpoll memory that we allocated. >
Hmm, seems you are right, read_lock should guarantee every slave on the list has the right ->dev... But I think I should keep that IS_UP() checking...
<...> >> >> /* close slave before restoring its mac address */ >> dev_close(slave_dev); >> @@ -2061,6 +2098,7 @@ static int bond_release_and_destroy(struct net_device *bond_dev, >> >> ret = bond_release(bond_dev, slave_dev); >> if ((ret == 0)&& (bond->slave_cnt == 0)) { >> + bond_dev->priv_flags |= IFF_DISABLE_NETPOLL; > Why are you setting IFF_DISABLE_NETPOLL here? That seems unnecessecary >
It gets removed in patch 2/2. :)
Thanks for review!
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