sunvnet - add missing rmb() for sunvnet driver

[pandora-kernel.git] / drivers / net / ethernet / sun / sunvnet.c

diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index d813bfb..f675396 100644 (file)
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c
@@ -32,6 +32,11 @@ MODULE_DESCRIPTION("Sun LDOM virtual network driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_MODULE_VERSION);
 
+/* Heuristic for the number of times to exponentially backoff and
+ * retry sending an LDC trigger when EAGAIN is encountered
+ */
+#define        VNET_MAX_RETRIES        10
+
 /* Ordered from largest major to lowest */
 static struct vio_version vnet_versions[] = {
        { .major = 1, .minor = 0 },
@@ -260,6 +265,7 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr,
                .state                  = vio_dring_state,
        };
        int err, delay;
+       int retries = 0;
 
        hdr.seq = dr->snd_nxt;
        delay = 1;
@@ -272,6 +278,13 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr,
                udelay(delay);
                if ((delay <<= 1) > 128)
                        delay = 128;
+               if (retries++ > VNET_MAX_RETRIES) {
+                       pr_info("ECONNRESET %x:%x:%x:%x:%x:%x\n",
+                               port->raddr[0], port->raddr[1],
+                               port->raddr[2], port->raddr[3],
+                               port->raddr[4], port->raddr[5]);
+                       err = -ECONNRESET;
+               }
        } while (err == -EAGAIN);
 
        return err;
@@ -337,14 +350,17 @@ static int vnet_walk_rx_one(struct vnet_port *port,
        if (IS_ERR(desc))
                return PTR_ERR(desc);
 
+       if (desc->hdr.state != VIO_DESC_READY)
+               return 1;
+
+       rmb();
+
        viodbg(DATA, "vio_walk_rx_one desc[%02x:%02x:%08x:%08x:%llx:%llx]\n",
               desc->hdr.state, desc->hdr.ack,
               desc->size, desc->ncookies,
               desc->cookies[0].cookie_addr,
               desc->cookies[0].cookie_size);
 
-       if (desc->hdr.state != VIO_DESC_READY)
-               return 1;
        err = vnet_rx_one(port, desc->size, desc->cookies, desc->ncookies);
        if (err == -ECONNRESET)
                return err;
@@ -475,8 +491,9 @@ static int handle_mcast(struct vnet_port *port, void *msgbuf)
        return 0;
 }
 
-static void maybe_tx_wakeup(struct vnet *vp)
+static void maybe_tx_wakeup(unsigned long param)
 {
+       struct vnet *vp = (struct vnet *)param;
        struct net_device *dev = vp->dev;
 
        netif_tx_lock(dev);
@@ -573,8 +590,13 @@ static void vnet_event(void *arg, int event)
                        break;
        }
        spin_unlock(&vio->lock);
+       /* Kick off a tasklet to wake the queue.  We cannot call
+        * maybe_tx_wakeup directly here because we could deadlock on
+        * netif_tx_lock() with dev_watchdog()
+        */
        if (unlikely(tx_wakeup && err != -ECONNRESET))
-               maybe_tx_wakeup(port->vp);
+               tasklet_schedule(&port->vp->vnet_tx_wakeup);
+
        local_irq_restore(flags);
 }
 
@@ -593,6 +615,7 @@ static int __vnet_tx_trigger(struct vnet_port *port)
                .end_idx                = (u32) -1,
        };
        int err, delay;
+       int retries = 0;
 
        hdr.seq = dr->snd_nxt;
        delay = 1;
@@ -605,6 +628,8 @@ static int __vnet_tx_trigger(struct vnet_port *port)
                udelay(delay);
                if ((delay <<= 1) > 128)
                        delay = 128;
+               if (retries++ > VNET_MAX_RETRIES)
+                       break;
        } while (err == -EAGAIN);
 
        return err;
@@ -691,7 +716,15 @@ static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
                memset(tx_buf+VNET_PACKET_SKIP+skb->len, 0, len - skb->len);
        }
 
-       d->hdr.ack = VIO_ACK_ENABLE;
+       /* We don't rely on the ACKs to free the skb in vnet_start_xmit(),
+        * thus it is safe to not set VIO_ACK_ENABLE for each transmission:
+        * the protocol itself does not require it as long as the peer
+        * sends a VIO_SUBTYPE_ACK for VIO_DRING_STOPPED.
+        *
+        * An ACK for every packet in the ring is expensive as the
+        * sending of LDC messages is slow and affects performance.
+        */
+       d->hdr.ack = VIO_ACK_DISABLE;
        d->size = len;
        d->ncookies = port->tx_bufs[dr->prod].ncookies;
        for (i = 0; i < d->ncookies; i++)
@@ -1046,6 +1079,7 @@ static struct vnet *vnet_new(const u64 *local_mac)
        vp = netdev_priv(dev);
 
        spin_lock_init(&vp->lock);
+       tasklet_init(&vp->vnet_tx_wakeup, maybe_tx_wakeup, (unsigned long)vp);
        vp->dev = dev;
 
        INIT_LIST_HEAD(&vp->port_list);
@@ -1105,6 +1139,7 @@ static void vnet_cleanup(void)
                vp = list_first_entry(&vnet_list, struct vnet, list);
                list_del(&vp->list);
                dev = vp->dev;
+               tasklet_kill(&vp->vnet_tx_wakeup);
                /* vio_unregister_driver() should have cleaned up port_list */
                BUG_ON(!list_empty(&vp->port_list));
                unregister_netdev(dev);