netpoll retry cleanup

The netpoll beast was still not happy. If the beast got
clogged pipes, it tended to stare blankly off in space
for a long time.

The problem couldn't be completely fixed because the
beast talked with irq's disabled. But it could be made
less painful and shorter.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>

2 files changed, 33 insertions, 39 deletions

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 93a8b7664423..c65d12ec7bb0 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -28,7 +28,6 @@ struct netpoll_info {
         atomic_t refcnt;
         spinlock_t poll_lock;
         int poll_owner;
-        int tries;
         int rx_flags;
         spinlock_t rx_lock;
         struct netpoll *rx_np; /* netpoll that registered an rx_hook */
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 93cb828f3aaf..6b34c394672f 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -34,12 +34,12 @@
 #define MAX_UDP_CHUNK 1460
 #define MAX_SKBS 32
 #define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
-#define MAX_RETRIES 20000
 
 static struct sk_buff_head skb_pool;
 
 static atomic_t trapped;
 
+#define USEC_PER_POLL   50
 #define NETPOLL_RX_ENABLED  1
 #define NETPOLL_RX_DROP     2
 
@@ -72,6 +72,7 @@ static void queue_process(void *p)
                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
                         return;
                 }
+
                 netif_tx_unlock_bh(dev);
         }
 }
@@ -244,50 +245,44 @@ repeat:
 
 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 {
-        int status;
-        struct netpoll_info *npinfo;
+        int status = NETDEV_TX_BUSY;
+        unsigned long tries;
+        struct net_device *dev = np->dev;
+        struct netpoll_info *npinfo = np->dev->npinfo;
+
+        if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
+                __kfree_skb(skb);
+                return;
+        }
+
+        /* don't get messages out of order, and no recursion */
+        if ( !(np->drop == netpoll_queue && skb_queue_len(&npinfo->txq))
+             && npinfo->poll_owner != smp_processor_id()
+             && netif_tx_trylock(dev)) {
+
+                /* try until next clock tick */
+                for(tries = jiffies_to_usecs(1)/USEC_PER_POLL; tries > 0; --tries) {
+                        if (!netif_queue_stopped(dev))
+                                status = dev->hard_start_xmit(skb, dev);
+
+                        if (status == NETDEV_TX_OK)
+                                break;
 
-        if (!np || !np->dev || !netif_running(np->dev)) {
-                __kfree_skb(skb);
-                return;
-        }
+                        /* tickle device maybe there is some cleanup */
+                        netpoll_poll(np);
 
-        npinfo = np->dev->npinfo;
+                        udelay(USEC_PER_POLL);
+                }
+                netif_tx_unlock(dev);
+        }
 
-        /* avoid recursion */
-        if (npinfo->poll_owner == smp_processor_id() ||
-            np->dev->xmit_lock_owner == smp_processor_id()) {
+        if (status != NETDEV_TX_OK) {
+                /* requeue for later */
                 if (np->drop)
                         np->drop(skb);
                 else
                         __kfree_skb(skb);
-                return;
         }
-
-        do {
-                npinfo->tries--;
-                netif_tx_lock(np->dev);
-
-                /*
-                 * network drivers do not expect to be called if the queue is
-                 * stopped.
-                 */
-                status = NETDEV_TX_BUSY;
-                if (!netif_queue_stopped(np->dev))
-                        status = np->dev->hard_start_xmit(skb, np->dev);
-
-                netif_tx_unlock(np->dev);
-
-                /* success */
-                if(!status) {
-                        npinfo->tries = MAX_RETRIES; /* reset */
-                        return;
-                }
-
-                /* transmit busy */
-                netpoll_poll(np);
-                udelay(50);
-        } while (npinfo->tries > 0);
 }
 
 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
@@ -649,7 +644,7 @@ int netpoll_setup(struct netpoll *np)
                 npinfo->rx_np = NULL;
                 spin_lock_init(&npinfo->poll_lock);
                 npinfo->poll_owner = -1;
-                npinfo->tries = MAX_RETRIES;
+
                 spin_lock_init(&npinfo->rx_lock);
                 skb_queue_head_init(&npinfo->arp_tx);
                 skb_queue_head_init(&npinfo->txq);