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>

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 93a8b76..c65d12e 100644 (file)
--- 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 93cb828..6b34c39 100644 (file)
--- 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);