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

Jason Wang
2016-06-30T04:01:25Z

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;
}

--
2.7.4