net_sched: plug in qdisc ops change_tx_queue_len

Introduce a new qdisc ops ->change_tx_queue_len() so that
each qdisc could decide how to implement this if it wants.
Previously we simply read dev->tx_queue_len, after pfifo_fast
switches to skb array, we need this API to resize the skb array
when we change dev->tx_queue_len.

To avoid handling race conditions with TX BH, we need to
deactivate all TX queues before change the value and bring them
back after we are done, this also makes implementation easier.

Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index eac43e8ca96da205b95fb903d8c596c2a75000d9..e2ab13687fb9741f3977b5452a958f8e886189f4 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -200,6 +200,7 @@ struct Qdisc_ops {
                                          struct nlattr *arg,
                                          struct netlink_ext_ack *extack);
        void                    (*attach)(struct Qdisc *sch);
+       int                     (*change_tx_queue_len)(struct Qdisc *, unsigned int);
 
        int                     (*dump)(struct Qdisc *, struct sk_buff *);
        int                     (*dump_stats)(struct Qdisc *, struct gnet_dump *);
@@ -489,6 +490,7 @@ void qdisc_class_hash_remove(struct Qdisc_class_hash *,
 void qdisc_class_hash_grow(struct Qdisc *, struct Qdisc_class_hash *);
 void qdisc_class_hash_destroy(struct Qdisc_class_hash *);
 
+int dev_qdisc_change_tx_queue_len(struct net_device *dev);
 void dev_init_scheduler(struct net_device *dev);
 void dev_shutdown(struct net_device *dev);
 void dev_activate(struct net_device *dev);

diff --git a/net/core/dev.c b/net/core/dev.c
index 520c24671bc53e3d13abdd463606a7e15ca177d3..dda9d7b9a840702d13b518507fef7a3723fce017 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7070,6 +7070,7 @@ int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)
                        dev->tx_queue_len = orig_len;
                        return res;
                }
+               return dev_qdisc_change_tx_queue_len(dev);
        }
 
        return 0;

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 1816bde47256083a411a966afa19cf804af1b9fa..08f9fa27e06e13d1ce6977b7cce22e2fd722b695 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1178,6 +1178,39 @@ void dev_deactivate(struct net_device *dev)
 }
 EXPORT_SYMBOL(dev_deactivate);
 
+static int qdisc_change_tx_queue_len(struct net_device *dev,
+                                    struct netdev_queue *dev_queue)
+{
+       struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
+       const struct Qdisc_ops *ops = qdisc->ops;
+
+       if (ops->change_tx_queue_len)
+               return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
+       return 0;
+}
+
+int dev_qdisc_change_tx_queue_len(struct net_device *dev)
+{
+       bool up = dev->flags & IFF_UP;
+       unsigned int i;
+       int ret = 0;
+
+       if (up)
+               dev_deactivate(dev);
+
+       for (i = 0; i < dev->num_tx_queues; i++) {
+               ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
+
+               /* TODO: revert changes on a partial failure */
+               if (ret)
+                       break;
+       }
+
+       if (up)
+               dev_activate(dev);
+       return ret;
+}
+
 static void dev_init_scheduler_queue(struct net_device *dev,
                                     struct netdev_queue *dev_queue,
                                     void *_qdisc)