[TG3]: Use status tag to check for new events

Use the status tag to determine if there are new events in
tg3_interrupt_tagged(). We discussed about this a while ago with Grant
Grundler and DaveM. This scheme makes it unnecessary to clear the
updated bit in the status block when using tagged mode, and only
a simple comparison is needed to determine if there are new events.

The tp->lock around netif_rx_complete() and tg3_restart_ints() is also
removed. It is unnecessary with DaveM's new locking scheme.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 17 deletions

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index eea418124be1..a629706e2b37 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -488,7 +488,8 @@ static void tg3_disable_ints(struct tg3 *tp)
 
 static inline void tg3_cond_int(struct tg3 *tp)
 {
-        if (tp->hw_status->status & SD_STATUS_UPDATED)
+        if (!(tp->tg3_flags & TG3_FLAG_TAGGED_STATUS) &&
+            (tp->hw_status->status & SD_STATUS_UPDATED))
                 tw32(GRC_LOCAL_CTRL, tp->grc_local_ctrl | GRC_LCLCTRL_SETINT);
 }
 
@@ -3220,18 +3221,17 @@ static int tg3_poll(struct net_device *netdev, int *budget)
                 netdev->quota -= work_done;
         }
 
-        if (tp->tg3_flags & TG3_FLAG_TAGGED_STATUS)
+        if (tp->tg3_flags & TG3_FLAG_TAGGED_STATUS) {
                 tp->last_tag = sblk->status_tag;
-        rmb();
-        sblk->status &= ~SD_STATUS_UPDATED;
+                rmb();
+        } else
+                sblk->status &= ~SD_STATUS_UPDATED;
 
         /* if no more work, tell net stack and NIC we're done */
         done = !tg3_has_work(tp);
         if (done) {
-                spin_lock(&tp->lock);
                 netif_rx_complete(netdev);
                 tg3_restart_ints(tp);
-                spin_unlock(&tp->lock);
         }
 
         return (done ? 0 : 1);
@@ -3351,7 +3351,7 @@ static irqreturn_t tg3_interrupt_tagged(int irq, void *dev_id, struct pt_regs *r
          * Reading the PCI State register will confirm whether the
          * interrupt is ours and will flush the status block.
          */
-        if ((sblk->status & SD_STATUS_UPDATED) ||
+        if ((sblk->status_tag != tp->last_tag) ||
             !(tr32(TG3PCI_PCISTATE) & PCISTATE_INT_NOT_ACTIVE)) {
                 /*
                  * writing any value to intr-mbox-0 clears PCI INTA# and
@@ -3362,20 +3362,17 @@ static irqreturn_t tg3_interrupt_tagged(int irq, void *dev_id, struct pt_regs *r
                  */
                 tw32_mailbox(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW,
                              0x00000001);
-                tp->last_tag = sblk->status_tag;
-                rmb();
                 if (tg3_irq_sync(tp))
                         goto out;
-                sblk->status &= ~SD_STATUS_UPDATED;
-                if (likely(tg3_has_work(tp))) {
+                if (netif_rx_schedule_prep(dev)) {
                         prefetch(&tp->rx_rcb[tp->rx_rcb_ptr]);
-                        netif_rx_schedule(dev);         /* schedule NAPI poll */
-                } else {
-                        /* no work, shared interrupt perhaps?  re-enable
-                         * interrupts, and flush that PCI write
+                        /* Update last_tag to mark that this status has been
+                         * seen. Because interrupt may be shared, we may be
+                         * racing with tg3_poll(), so only update last_tag
+                         * if tg3_poll() is not scheduled.
                          */
-                        tw32_mailbox_f(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW,
-                                       tp->last_tag << 24);
+                        tp->last_tag = sblk->status_tag;
+                        __netif_rx_schedule(dev);
                 }
         } else {        /* shared interrupt */
                 handled = 0;
@@ -6238,6 +6235,7 @@ static int tg3_test_interrupt(struct tg3 *tp)
         if (err)
                 return err;
 
+        tp->hw_status->status &= ~SD_STATUS_UPDATED;
         tg3_enable_ints(tp);
 
         tw32_f(HOSTCC_MODE, tp->coalesce_mode | HOSTCC_MODE_ENABLE |