net: Add queue state xoff flag for stack

Create separate queue state flags so that either the stack or drivers
can turn on XOFF.  Added a set of functions used in the stack to determine
if a queue is really stopped (either by stack or driver)

Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 46 insertions, 25 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ac9a4b9344ca..d19f93265cac 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -517,11 +517,23 @@ static inline void napi_synchronize(const struct napi_struct *n)
 #endif
 
 enum netdev_queue_state_t {
-        __QUEUE_STATE_XOFF,
+        __QUEUE_STATE_DRV_XOFF,
+        __QUEUE_STATE_STACK_XOFF,
         __QUEUE_STATE_FROZEN,
-#define QUEUE_STATE_XOFF_OR_FROZEN ((1 << __QUEUE_STATE_XOFF)           | \
-                                    (1 << __QUEUE_STATE_FROZEN))
+#define QUEUE_STATE_ANY_XOFF ((1 << __QUEUE_STATE_DRV_XOFF)             | \
+                              (1 << __QUEUE_STATE_STACK_XOFF))
+#define QUEUE_STATE_ANY_XOFF_OR_FROZEN (QUEUE_STATE_ANY_XOFF            | \
+                                        (1 << __QUEUE_STATE_FROZEN))
 };
+/*
+ * __QUEUE_STATE_DRV_XOFF is used by drivers to stop the transmit queue.  The
+ * netif_tx_* functions below are used to manipulate this flag.  The
+ * __QUEUE_STATE_STACK_XOFF flag is used by the stack to stop the transmit
+ * queue independently.  The netif_xmit_*stopped functions below are called
+ * to check if the queue has been stopped by the driver or stack (either
+ * of the XOFF bits are set in the state).  Drivers should not need to call
+ * netif_xmit*stopped functions, they should only be using netif_tx_*.
+ */
 
 struct netdev_queue {
 /*
@@ -1718,7 +1730,7 @@ 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))
+        if (!(txq->state & QUEUE_STATE_ANY_XOFF))
                 __netif_schedule(txq->qdisc);
 }
 
@@ -1732,7 +1744,7 @@ static inline void netif_tx_schedule_all(struct net_device *dev)
 
 static inline void netif_tx_start_queue(struct netdev_queue *dev_queue)
 {
-        clear_bit(__QUEUE_STATE_XOFF, &dev_queue->state);
+        clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state);
 }
 
 /**
@@ -1764,7 +1776,7 @@ static inline void netif_tx_wake_queue(struct netdev_queue *dev_queue)
                 return;
         }
 #endif
-        if (test_and_clear_bit(__QUEUE_STATE_XOFF, &dev_queue->state))
+        if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state))
                 __netif_schedule(dev_queue->qdisc);
 }
 
@@ -1796,7 +1808,7 @@ static inline void netif_tx_stop_queue(struct netdev_queue *dev_queue)
                 pr_info("netif_stop_queue() cannot be called before register_netdev()\n");
                 return;
         }
-        set_bit(__QUEUE_STATE_XOFF, &dev_queue->state);
+        set_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state);
 }
 
 /**
@@ -1823,7 +1835,7 @@ static inline void netif_tx_stop_all_queues(struct net_device *dev)
 
 static inline int netif_tx_queue_stopped(const struct netdev_queue *dev_queue)
 {
-        return test_bit(__QUEUE_STATE_XOFF, &dev_queue->state);
+        return test_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state);
 }
 
 /**
@@ -1837,9 +1849,16 @@ static inline int netif_queue_stopped(const struct net_device *dev)
         return netif_tx_queue_stopped(netdev_get_tx_queue(dev, 0));
 }
 
-static inline int netif_tx_queue_frozen_or_stopped(const struct netdev_queue *dev_queue)
+static inline int netif_xmit_stopped(const struct netdev_queue *dev_queue)
 {
-        return dev_queue->state & QUEUE_STATE_XOFF_OR_FROZEN;
+        return dev_queue->state & QUEUE_STATE_ANY_XOFF;
+}
+
+static inline int netif_xmit_frozen_or_stopped(const struct netdev_queue *dev_queue)
+{
+        return dev_queue->state & QUEUE_STATE_ANY_XOFF_OR_FROZEN;
+}
+
 }
 
 /**
@@ -1926,7 +1945,7 @@ static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
         if (netpoll_trap())
                 return;
 #endif
-        if (test_and_clear_bit(__QUEUE_STATE_XOFF, &txq->state))
+        if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &txq->state))
                 __netif_schedule(txq->qdisc);
 }
 
diff --git a/net/core/dev.c b/net/core/dev.c
index c7ef6c5d3782..cb8f753b4238 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2270,7 +2270,7 @@ gso:
                         return rc;
                 }
                 txq_trans_update(txq);
-                if (unlikely(netif_tx_queue_stopped(txq) && skb->next))
+                if (unlikely(netif_xmit_stopped(txq) && skb->next))
                         return NETDEV_TX_BUSY;
         } while (skb->next);
 
@@ -2558,7 +2558,7 @@ int dev_queue_xmit(struct sk_buff *skb)
 
                         HARD_TX_LOCK(dev, txq, cpu);
 
-                        if (!netif_tx_queue_stopped(txq)) {
+                        if (!netif_xmit_stopped(txq)) {
                                 __this_cpu_inc(xmit_recursion);
                                 rc = dev_hard_start_xmit(skb, dev, txq);
                                 __this_cpu_dec(xmit_recursion);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 1a7d8e2c9768..0d38808a2305 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -76,7 +76,7 @@ static void queue_process(struct work_struct *work)
 
                 local_irq_save(flags);
                 __netif_tx_lock(txq, smp_processor_id());
-                if (netif_tx_queue_frozen_or_stopped(txq) ||
+                if (netif_xmit_frozen_or_stopped(txq) ||
                     ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
                         skb_queue_head(&npinfo->txq, skb);
                         __netif_tx_unlock(txq);
@@ -317,7 +317,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
                      tries > 0; --tries) {
                         if (__netif_tx_trylock(txq)) {
-                                if (!netif_tx_queue_stopped(txq)) {
+                                if (!netif_xmit_stopped(txq)) {
                                         status = ops->ndo_start_xmit(skb, dev);
                                         if (status == NETDEV_TX_OK)
                                                 txq_trans_update(txq);
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index aa53a35a631b..449fe0f068f8 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3342,7 +3342,7 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
 
         __netif_tx_lock_bh(txq);
 
-        if (unlikely(netif_tx_queue_frozen_or_stopped(txq))) {
+        if (unlikely(netif_xmit_frozen_or_stopped(txq))) {
                 ret = NETDEV_TX_BUSY;
                 pkt_dev->last_ok = 0;
                 goto unlock;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 79ac1458c2ba..67fc573e013a 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -60,7 +60,7 @@ static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
 
                 /* check the reason of requeuing without tx lock first */
                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
-                if (!netif_tx_queue_frozen_or_stopped(txq)) {
+                if (!netif_xmit_frozen_or_stopped(txq)) {
                         q->gso_skb = NULL;
                         q->q.qlen--;
                 } else
@@ -121,7 +121,7 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
         spin_unlock(root_lock);
 
         HARD_TX_LOCK(dev, txq, smp_processor_id());
-        if (!netif_tx_queue_frozen_or_stopped(txq))
+        if (!netif_xmit_frozen_or_stopped(txq))
                 ret = dev_hard_start_xmit(skb, dev, txq);
 
         HARD_TX_UNLOCK(dev, txq);
@@ -143,7 +143,7 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
                 ret = dev_requeue_skb(skb, q);
         }
 
-        if (ret && netif_tx_queue_frozen_or_stopped(txq))
+        if (ret && netif_xmit_frozen_or_stopped(txq))
                 ret = 0;
 
         return ret;
@@ -242,7 +242,7 @@ static void dev_watchdog(unsigned long arg)
                                  * old device drivers set dev->trans_start
                                  */
                                 trans_start = txq->trans_start ? : dev->trans_start;
-                                if (netif_tx_queue_stopped(txq) &&
+                                if (netif_xmit_stopped(txq) &&
                                     time_after(jiffies, (trans_start +
                                                          dev->watchdog_timeo))) {
                                         some_queue_timedout = 1;
diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c
index edc1950e0e77..49131d7a7446 100644
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -107,7 +107,8 @@ static struct sk_buff *multiq_dequeue(struct Qdisc *sch)
                 /* Check that target subqueue is available before
                  * pulling an skb to avoid head-of-line blocking.
                  */
-                if (!__netif_subqueue_stopped(qdisc_dev(sch), q->curband)) {
+                if (!netif_xmit_stopped(
+                    netdev_get_tx_queue(qdisc_dev(sch), q->curband))) {
                         qdisc = q->queues[q->curband];
                         skb = qdisc->dequeue(qdisc);
                         if (skb) {
@@ -138,7 +139,8 @@ static struct sk_buff *multiq_peek(struct Qdisc *sch)
                 /* Check that target subqueue is available before
                  * pulling an skb to avoid head-of-line blocking.
                  */
-                if (!__netif_subqueue_stopped(qdisc_dev(sch), curband)) {
+                if (!netif_xmit_stopped(
+                    netdev_get_tx_queue(qdisc_dev(sch), curband))) {
                         qdisc = q->queues[curband];
                         skb = qdisc->ops->peek(qdisc);
                         if (skb)
diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index a3b7120fcc74..283bfe3de59d 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -301,7 +301,7 @@ restart:
 
                 if (slave_txq->qdisc_sleeping != q)
                         continue;
-                if (__netif_subqueue_stopped(slave, subq) ||
+                if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) ||
                     !netif_running(slave)) {
                         busy = 1;
                         continue;
@@ -312,7 +312,7 @@ restart:
                         if (__netif_tx_trylock(slave_txq)) {
                                 unsigned int length = qdisc_pkt_len(skb);
 
-                                if (!netif_tx_queue_frozen_or_stopped(slave_txq) &&
+                                if (!netif_xmit_frozen_or_stopped(slave_txq) &&
                                     slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) {
                                         txq_trans_update(slave_txq);
                                         __netif_tx_unlock(slave_txq);
@@ -324,7 +324,7 @@ restart:
                                 }
                                 __netif_tx_unlock(slave_txq);
                         }
-                        if (netif_queue_stopped(dev))
+                        if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0)))
                                 busy = 1;
                         break;
                 case 1: