netxen: napi and irq cleanup

o separate and simpler irq handler for msi interrupts, avoids few checks
  than legacy mode.
o avoid redudant tx_has_work() and rx_has_work() checks in interrupt
  and napi, which can uncork irq based on racy (lockless) access to tx
  and rx ring indices. If we get interrupt, there's sufficient reason to
  schedule napi.
o replenish rx ring more often, remove self-imposed threshold rcv_free
  that prevents posting rx desc to card. This improves performance in
  low memory.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Tested-by: Vernon Mauery <mauery@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 39 insertions, 74 deletions

diff --git a/drivers/net/netxen/netxen_nic_main.c b/drivers/net/netxen/netxen_nic_main.c
index cd665da85c7..95955204ef5 100644
--- a/drivers/net/netxen/netxen_nic_main.c
+++ b/drivers/net/netxen/netxen_nic_main.c
@@ -63,12 +63,12 @@ static int netxen_nic_xmit_frame(struct sk_buff *, struct net_device *);
 static void netxen_tx_timeout(struct net_device *netdev);
 static void netxen_tx_timeout_task(struct work_struct *work);
 static void netxen_watchdog(unsigned long);
-static int netxen_handle_int(struct netxen_adapter *, struct net_device *);
 static int netxen_nic_poll(struct napi_struct *napi, int budget);
 #ifdef CONFIG_NET_POLL_CONTROLLER
 static void netxen_nic_poll_controller(struct net_device *netdev);
 #endif
 static irqreturn_t netxen_intr(int irq, void *data);
+static irqreturn_t netxen_msi_intr(int irq, void *data);
 
 int physical_port[] = {0, 1, 2, 3};
 
@@ -405,7 +405,7 @@ netxen_nic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
         netdev->set_mac_address    = netxen_nic_set_mac;
         netdev->change_mtu         = netxen_nic_change_mtu;
         netdev->tx_timeout         = netxen_tx_timeout;
-        netdev->watchdog_timeo     = HZ;
+        netdev->watchdog_timeo     = 2*HZ;
 
         netxen_nic_change_mtu(netdev, netdev->mtu);
 
@@ -823,6 +823,8 @@ static int netxen_nic_open(struct net_device *netdev)
         struct netxen_adapter *adapter = (struct netxen_adapter *)netdev->priv;
         int err = 0;
         int ctx, ring;
+        irq_handler_t handler;
+        unsigned long flags = IRQF_SAMPLE_RANDOM;
 
         if (adapter->is_up != NETXEN_ADAPTER_UP_MAGIC) {
                 err = netxen_init_firmware(adapter);
@@ -846,9 +848,14 @@ static int netxen_nic_open(struct net_device *netdev)
                                 netxen_post_rx_buffers(adapter, ctx, ring);
                 }
                 adapter->irq = adapter->ahw.pdev->irq;
-                err = request_irq(adapter->ahw.pdev->irq, netxen_intr,
-                                  IRQF_SHARED|IRQF_SAMPLE_RANDOM, netdev->name,
-                                  adapter);
+                if (adapter->flags & NETXEN_NIC_MSI_ENABLED)
+                        handler = netxen_msi_intr;
+                else {
+                        flags |= IRQF_SHARED;
+                        handler = netxen_intr;
+                }
+                err = request_irq(adapter->irq, handler,
+                                  flags, netdev->name, adapter);
                 if (err) {
                         printk(KERN_ERR "request_irq failed with: %d\n", err);
                         netxen_free_hw_resources(adapter);
@@ -857,21 +864,12 @@ static int netxen_nic_open(struct net_device *netdev)
 
                 adapter->is_up = NETXEN_ADAPTER_UP_MAGIC;
         }
-        if (!adapter->driver_mismatch)
-                mod_timer(&adapter->watchdog_timer, jiffies);
-
-        napi_enable(&adapter->napi);
-
-        netxen_nic_enable_int(adapter);
-
         /* Done here again so that even if phantom sw overwrote it,
          * we set it */
         if (adapter->init_port
             && adapter->init_port(adapter, adapter->portnum) != 0) {
-            del_timer_sync(&adapter->watchdog_timer);
                 printk(KERN_ERR "%s: Failed to initialize port %d\n",
                                 netxen_nic_driver_name, adapter->portnum);
-                napi_disable(&adapter->napi);
                 return -EIO;
         }
         if (adapter->macaddr_set)
@@ -884,6 +882,12 @@ static int netxen_nic_open(struct net_device *netdev)
                 adapter->set_mtu(adapter, netdev->mtu);
 
         if (!adapter->driver_mismatch)
+                mod_timer(&adapter->watchdog_timer, jiffies);
+
+        napi_enable(&adapter->napi);
+        netxen_nic_enable_int(adapter);
+
+        if (!adapter->driver_mismatch)
                 netif_start_queue(netdev);
 
         return 0;
@@ -1196,81 +1200,50 @@ static void netxen_tx_timeout_task(struct work_struct *work)
         netif_wake_queue(adapter->netdev);
 }
 
-static int
-netxen_handle_int(struct netxen_adapter *adapter, struct net_device *netdev)
+static inline void
+netxen_handle_int(struct netxen_adapter *adapter)
 {
-        u32 ret = 0;
-
-        DPRINTK(INFO, "Entered handle ISR\n");
-        adapter->stats.ints++;
-
         netxen_nic_disable_int(adapter);
-
-        if (netxen_nic_rx_has_work(adapter) || netxen_nic_tx_has_work(adapter)) {
-                if (netif_rx_schedule_prep(netdev, &adapter->napi)) {
-                        /*
-                         * Interrupts are already disabled.
-                         */
-                        __netif_rx_schedule(netdev, &adapter->napi);
-                } else {
-                        static unsigned int intcount = 0;
-                        if ((++intcount & 0xfff) == 0xfff)
-                                DPRINTK(KERN_ERR
-                                       "%s: %s interrupt %d while in poll\n",
-                                       netxen_nic_driver_name, netdev->name,
-                                       intcount);
-                }
-                ret = 1;
-        }
-
-        if (ret == 0) {
-                netxen_nic_enable_int(adapter);
-        }
-
-        return ret;
+        napi_schedule(&adapter->napi);
 }
 
-/*
- * netxen_intr - Interrupt Handler
- * @irq: interrupt number
- * data points to adapter stucture (which may be handling more than 1 port
- */
 irqreturn_t netxen_intr(int irq, void *data)
 {
         struct netxen_adapter *adapter = data;
-        struct net_device *netdev = adapter->netdev;
         u32 our_int = 0;
 
-        if (!(adapter->flags & NETXEN_NIC_MSI_ENABLED)) {
-                our_int = readl(NETXEN_CRB_NORMALIZE(adapter, CRB_INT_VECTOR));
-                /* not our interrupt */
-                if ((our_int & (0x80 << adapter->portnum)) == 0)
-                        return IRQ_NONE;
-        }
+        our_int = readl(NETXEN_CRB_NORMALIZE(adapter, CRB_INT_VECTOR));
+        /* not our interrupt */
+        if ((our_int & (0x80 << adapter->portnum)) == 0)
+                return IRQ_NONE;
 
         if (adapter->intr_scheme == INTR_SCHEME_PERPORT) {
                 /* claim interrupt */
-                if (!(adapter->flags & NETXEN_NIC_MSI_ENABLED)) {
-                        writel(our_int & ~((u32)(0x80 << adapter->portnum)),
+                writel(our_int & ~((u32)(0x80 << adapter->portnum)),
                         NETXEN_CRB_NORMALIZE(adapter, CRB_INT_VECTOR));
-                }
         }
 
-        if (netif_running(netdev))
-                netxen_handle_int(adapter, netdev);
+        netxen_handle_int(adapter);
 
         return IRQ_HANDLED;
 }
 
+irqreturn_t netxen_msi_intr(int irq, void *data)
+{
+        struct netxen_adapter *adapter = data;
+
+        netxen_handle_int(adapter);
+        return IRQ_HANDLED;
+}
+
 static int netxen_nic_poll(struct napi_struct *napi, int budget)
 {
         struct netxen_adapter *adapter = container_of(napi, struct netxen_adapter, napi);
-        struct net_device *netdev = adapter->netdev;
-        int done = 1;
+        int tx_complete;
         int ctx;
         int work_done;
 
-        DPRINTK(INFO, "polling for %d descriptors\n", *budget);
+        tx_complete = netxen_process_cmd_ring(adapter);
 
         work_done = 0;
         for (ctx = 0; ctx < MAX_RCV_CTX; ++ctx) {
@@ -1290,16 +1263,8 @@ static int netxen_nic_poll(struct napi_struct *napi, int budget)
                                                      budget / MAX_RCV_CTX);
         }
 
-        if (work_done >= budget)
-                done = 0;
-
-        if (netxen_process_cmd_ring((unsigned long)adapter) == 0)
-                done = 0;
-
-        DPRINTK(INFO, "new work_done: %d work_to_do: %d\n",
-                work_done, work_to_do);
-        if (done) {
-                netif_rx_complete(netdev, napi);
+        if ((work_done < budget) && tx_complete) {
+                netif_rx_complete(adapter->netdev, &adapter->napi);
                 netxen_nic_enable_int(adapter);
         }