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>

1 files changed, 30 insertions, 11 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);
 }