pkt_sched: Schedule qdiscs instead of netdev_queue.

When we have shared qdiscs, packets come out of the qdiscs
for multiple transmit queues.

Therefore it doesn't make any sense to schedule the transmit
queue when logically we cannot know ahead of time the TX
queue of the SKB that the qdisc->dequeue() will give us.

Just for sanity I added a BUG check to make sure we never
get into a state where the noop_qdisc is scheduled.

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 11 insertions, 14 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9240a95793be..1e839fa01434 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -275,7 +275,6 @@ enum netdev_state_t
 {
         __LINK_STATE_START,
         __LINK_STATE_PRESENT,
-        __LINK_STATE_SCHED,
         __LINK_STATE_NOCARRIER,
         __LINK_STATE_LINKWATCH_PENDING,
         __LINK_STATE_DORMANT,
@@ -452,7 +451,6 @@ struct netdev_queue {
         int                     xmit_lock_owner;
         struct Qdisc            *qdisc_sleeping;
         struct list_head        qdisc_list;
-        struct netdev_queue     *next_sched;
 } ____cacheline_aligned_in_smp;
 
 /*
@@ -969,7 +967,7 @@ static inline int unregister_gifconf(unsigned int family)
  */
 struct softnet_data
 {
-        struct netdev_queue     *output_queue;
+        struct Qdisc            *output_queue;
         struct sk_buff_head     input_pkt_queue;
         struct list_head        poll_list;
         struct sk_buff          *completion_queue;
@@ -984,12 +982,12 @@ DECLARE_PER_CPU(struct softnet_data,softnet_data);
 
 #define HAVE_NETIF_QUEUE
 
-extern void __netif_schedule(struct netdev_queue *txq);
+extern void __netif_schedule(struct Qdisc *q);
 
 static inline void netif_schedule_queue(struct netdev_queue *txq)
 {
         if (!test_bit(__QUEUE_STATE_XOFF, &txq->state))
-                __netif_schedule(txq);
+                __netif_schedule(txq->qdisc);
 }
 
 static inline void netif_tx_schedule_all(struct net_device *dev)
@@ -1042,7 +1040,7 @@ static inline void netif_tx_wake_queue(struct netdev_queue *dev_queue)
         }
 #endif
         if (test_and_clear_bit(__QUEUE_STATE_XOFF, &dev_queue->state))
-                __netif_schedule(dev_queue);
+                __netif_schedule(dev_queue->qdisc);
 }
 
 static inline void netif_wake_queue(struct net_device *dev)
@@ -1186,7 +1184,7 @@ static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
                 return;
 #endif
         if (test_and_clear_bit(__QUEUE_STATE_XOFF, &txq->state))
-                __netif_schedule(txq);
+                __netif_schedule(txq->qdisc);
 }
 
 /**
diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index 06a442d85186..e4e30052e4e2 100644
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -84,15 +84,12 @@ extern struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,
                 struct nlattr *tab);
 extern void qdisc_put_rtab(struct qdisc_rate_table *tab);
 
-extern void __qdisc_run(struct netdev_queue *txq);
+extern void __qdisc_run(struct Qdisc *q);
 
-static inline void qdisc_run(struct netdev_queue *txq)
+static inline void qdisc_run(struct Qdisc *q)
 {
-        struct Qdisc *q = txq->qdisc;
-
-        if (!netif_tx_queue_stopped(txq) &&
-            !test_and_set_bit(__QDISC_STATE_RUNNING, &q->state))
-                __qdisc_run(txq);
+        if (!test_and_set_bit(__QDISC_STATE_RUNNING, &q->state))
+                __qdisc_run(q);
 }
 
 extern int tc_classify_compat(struct sk_buff *skb, struct tcf_proto *tp,
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 92417825d387..3cc4b5cd8c6a 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -26,6 +26,7 @@ struct qdisc_rate_table
 enum qdisc_state_t
 {
         __QDISC_STATE_RUNNING,
+        __QDISC_STATE_SCHED,
 };
 
 struct Qdisc
@@ -45,6 +46,7 @@ struct Qdisc
         struct sk_buff          *gso_skb;
         struct sk_buff_head     q;
         struct netdev_queue     *dev_queue;
+        struct Qdisc            *next_sched;
         struct list_head        list;
 
         struct gnet_stats_basic bstats;