Re: [PATCH net-next V3 5/6] net: introduce NETDEV_CHANGE_TX_QUEUE_LEN

[Jason Wang]

On 2016å06æ30æ 13:12, Jason Wang wrote:
> On 2016å06æ30æ 12:56, John Fastabend wrote:
> > On 16-06-29 08:52 PM, Jason Wang wrote:
> > > This patch introduces a new event - NETDEV_CHANGE_TX_QUEUE_LEN, this
> > > will be triggered when tx_queue_len. It could be used by net device
> > > who want to do some processing at that time. An example is tun who may
> > > want to resize tx array when tx_queue_len is changed.
> > >
> > > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > > ---
> > >   include/linux/netdevice.h |  1 +
> > >   net/core/net-sysfs.c      | 15 ++++++++++++++-
> > >   2 files changed, 15 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > > index e84d9d2..7dc2ec7 100644
> > > --- a/include/linux/netdevice.h
> > > +++ b/include/linux/netdevice.h
> > > @@ -2237,6 +2237,7 @@ struct netdev_lag_lower_state_info {
> > >   #define NETDEV_PRECHANGEUPPER    0x001A
> > >   #define NETDEV_CHANGELOWERSTATE    0x001B
> > >   #define NETDEV_UDP_TUNNEL_PUSH_INFO    0x001C
> > > +#define NETDEV_CHANGE_TX_QUEUE_LEN    0x001E
> > >     int register_netdevice_notifier(struct notifier_block *nb);
> > >   int unregister_netdevice_notifier(struct notifier_block *nb);
> > > diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> > > index 7a0b616..6e4f347 100644
> > > --- a/net/core/net-sysfs.c
> > > +++ b/net/core/net-sysfs.c
> > > @@ -322,7 +322,20 @@ NETDEVICE_SHOW_RW(flags, fmt_hex);
> > >     static int change_tx_queue_len(struct net_device *dev, unsigned 
> > > long new_len)
> > >   {
> > > -    dev->tx_queue_len = new_len;
> > > +    int res, orig_len = dev->tx_queue_len;
> > > +
> > > +    if (new_len != orig_len) {
> > > +        dev->tx_queue_len = new_len;
> > > +        res = call_netdevice_notifiers(NETDEV_CHANGE_TX_QUEUE_LEN, 
> > > dev);
> > > +        res = notifier_to_errno(res);
> > > +        if (res) {
> > > +            netdev_err(dev,
> > > +                   "refused to change device tx_queue_len\n");
> > > +            dev->tx_queue_len = orig_len;
> > > +            return -EFAULT;
> > > +        }
> > > +    }
> > > +
> > >       return 0;
> > >   }
> > Acked-by: John Fastabend <john.r.fastabend@xxxxxxxxx>
> >
> > Great timing I was just looking into this because I need it for the
> > qdisc side.
> >
> > It looks like this covers the sysfs change but the tx_queue_len can
> > also be changed via rtnetlink as well. So we need another patch for
> > that path right?
> >
> >          if (tb[IFLA_TXQLEN]) {
> >                  unsigned long value = nla_get_u32(tb[IFLA_TXQLEN]);
> >
> >                  if (dev->tx_queue_len ^ value)
> >                          status |= DO_SETLINK_NOTIFY;
> >
> >                  dev->tx_queue_len = value;
> >          }
> >
> > Thanks,
> > John
>
> Right, will do this in next version.
>
> Thanks

Ok, since Michael has acked on the series, will prepare a patch on top.

Thanks