[PATCH] sky2: fix NAPI and receive handling

Speed up the receive and interrupt processing and eliminate a
couple of race conditions from NAPI code.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 30 insertions, 33 deletions

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 92d69fff8755..a85a8d16908f 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -76,7 +76,7 @@
 
 #define RX_LE_SIZE              256
 #define RX_LE_BYTES             (RX_LE_SIZE*sizeof(struct sky2_rx_le))
-#define RX_MAX_PENDING          (RX_LE_SIZE/2 - 1)
+#define RX_MAX_PENDING          (RX_LE_SIZE/2 - 2)
 #define RX_DEF_PENDING          128
 #define RX_COPY_THRESHOLD       256
 
@@ -690,7 +690,7 @@ static inline void sky2_put_idx(struct sky2_hw *hw, unsigned q,
 setnew:
                 sky2_write16(hw, Y2_QADDR(q, PREF_UNIT_PUT_IDX), idx);
         }
-        *last = sky2_read16(hw, Y2_QADDR(q, PREF_UNIT_PUT_IDX));
+        *last = idx;
 }
 
 
@@ -723,15 +723,6 @@ static inline void sky2_rx_add(struct sky2_port *sky2, struct ring_info *re)
         le->opcode = OP_PACKET | HW_OWNER;
 }
 
-/* Tell receiver about new buffers. */
-static inline void rx_set_put(struct net_device *dev)
-{
-        struct sky2_port *sky2 = netdev_priv(dev);
-
-        if (sky2->rx_last_put != sky2->rx_put)
-                sky2_put_idx(sky2->hw, rxqaddr[sky2->port], sky2->rx_put,
-                             &sky2->rx_last_put, RX_LE_SIZE);
-}
 
 /* Tell chip where to start receive checksum.
  * Actually has two checksums, but set both same to avoid possible byte
@@ -1616,6 +1607,10 @@ resubmit:
         re->skb->ip_summed = CHECKSUM_NONE;
         sky2_rx_add(sky2, re);
 
+        /* Tell receiver about new buffers. */
+        sky2_put_idx(sky2->hw, rxqaddr[sky2->port], sky2->rx_put,
+                     &sky2->rx_last_put, RX_LE_SIZE);
+
         return skb;
 
 error:
@@ -1664,16 +1659,26 @@ static int sky2_poll(struct net_device *dev0, int *budget)
         hwidx = sky2_read16(hw, STAT_PUT_IDX);
         BUG_ON(hwidx >= STATUS_RING_SIZE);
         rmb();
-        while (hw->st_idx != hwidx && work_done < to_do) {
+
+        do {
                 struct sky2_status_le *le = hw->st_le + hw->st_idx;
                 struct sky2_port *sky2;
                 struct sk_buff *skb;
                 u32 status;
                 u16 length;
 
-                BUG_ON(le->link >= hw->ports);
-                if (!hw->dev[le->link])
-                        goto skip;
+                /* Are we done yet? */
+                if (hw->st_idx == hwidx) {
+                        sky2_write32(hw, STAT_CTRL, SC_STAT_CLR_IRQ);
+                        hwidx = sky2_read16(hw, STAT_PUT_IDX);
+                        if (hwidx == hw->st_idx)
+                                break;
+                }
+
+                hw->st_idx = (hw->st_idx + 1) % STATUS_RING_SIZE;
+                prefetch(&hw->st_le[hw->st_idx]);
+
+                BUG_ON(le->link >= hw->ports || !hw->dev[le->link]);
 
                 sky2 = netdev_priv(hw->dev[le->link]);
                 status = le32_to_cpu(le->status);
@@ -1692,6 +1697,7 @@ static int sky2_poll(struct net_device *dev0, int *budget)
                         } else
 #endif
                                 netif_receive_skb(skb);
+                        ++work_done;
                         break;
 
 #ifdef SKY2_VLAN_TAG_USED
@@ -1722,22 +1728,11 @@ static int sky2_poll(struct net_device *dev0, int *budget)
                         break;
                 }
 
-        skip:
-                hw->st_idx = (hw->st_idx + 1) % STATUS_RING_SIZE;
-                if (hw->st_idx == hwidx) {
-                        hwidx = sky2_read16(hw, STAT_PUT_IDX);
-                        rmb();
-                }
-        }
+                le->opcode = 0; /* paranoia */
+        } while (work_done < to_do);
 
         mmiowb();
 
-        if (hw->dev[0])
-                rx_set_put(hw->dev[0]);
-
-        if (hw->dev[1])
-                rx_set_put(hw->dev[1]);
-
         *budget -= work_done;
         dev0->quota -= work_done;
         if (work_done < to_do) {
@@ -1750,10 +1745,10 @@ static int sky2_poll(struct net_device *dev0, int *budget)
                         sky2_write8(hw, STAT_TX_TIMER_CTRL, TIM_START);
                 }
 
+                netif_rx_complete(dev0);
                 hw->intr_mask |= Y2_IS_STAT_BMU;
                 sky2_write32(hw, B0_IMSK, hw->intr_mask);
                 sky2_read32(hw, B0_IMSK);
-                netif_rx_complete(dev0);
         }
 
         return work_done >= to_do;
@@ -1880,6 +1875,7 @@ static void sky2_phy_intr(struct sky2_hw *hw, unsigned port)
 static irqreturn_t sky2_intr(int irq, void *dev_id, struct pt_regs *regs)
 {
         struct sky2_hw *hw = dev_id;
+        struct net_device *dev0 = hw->dev[0];
         u32 status;
 
         status = sky2_read32(hw, B0_Y2_SP_ISRC2);
@@ -1890,12 +1886,13 @@ static irqreturn_t sky2_intr(int irq, void *dev_id, struct pt_regs *regs)
                 sky2_hw_intr(hw);
 
         /* Do NAPI for Rx and Tx status */
-        if ((status & Y2_IS_STAT_BMU) && netif_rx_schedule_test(hw->dev[0])) {
-                sky2_write32(hw, STAT_CTRL, SC_STAT_CLR_IRQ);
-
+        if (status & Y2_IS_STAT_BMU) {
                 hw->intr_mask &= ~Y2_IS_STAT_BMU;
                 sky2_write32(hw, B0_IMSK, hw->intr_mask);
-                __netif_rx_schedule(hw->dev[0]);
+                prefetch(&hw->st_le[hw->st_idx]);
+
+                if (netif_rx_schedule_test(dev0))
+                        __netif_rx_schedule(dev0);
         }
 
         if (status & Y2_IS_IRQ_PHY1)