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

Jason Wang
2016-06-30T06:51:50Z

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 <jasowang@redhat.com>
>>>> ---
>>>> 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@intel.com>
>>>
>>> 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