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

From: Jason Wang <[email-masked]>
Date: Thu, 30 Jun 2016 14:43:00 +0800

On 2016年06月30日 13:59, Jason Wang wrote:
>
>
> On 2016年06月30日 13:12, Jason Wang wrote:
>>
>>
>> On 2016年06月30日 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 <[email-masked]>
>>>> ---
>>>>   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 <[email-masked]>
>>>
>>> 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 

Since kbuild test robot has found a minor issue on this series, I will 
post v4 with this fixed.

Thanks
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