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

Jason Wang
2016-06-30T05:13:14Z

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