lkml.org 
[lkml]   [2010]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [v3 PATCH 1/2] bonding: sync netpoll code with bridge
    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!


    \
     
     \ /
      Last update: 2010-12-09 08:37    [W:0.025 / U:0.172 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site