[TG3]: Fix missing memory barriers and SD_STATUS_UPDATED bit clearing.

There must be a rmb() between reading the status block tag
and calling tg3_has_work().  This was missing in tg3_mis()
and tg3_interrupt_tagged().  tg3_poll() got it right.

Also, SD_STATUS_UPDATED must be cleared in the status block
right before we call tg3_has_work().  Only tg3_poll() got this
wrong.

Based upon patches and commentary from Grant Grundler and
Michael Chan.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index a0b8848049c9ede346a9160c370d0b1df49c2798..fef1d087107c18a19dc509aaa8f8663e9ca270dd 100644 (file)
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -2929,6 +2929,7 @@ static int tg3_poll(struct net_device *netdev, int *budget)
        if (tp->tg3_flags & TG3_FLAG_TAGGED_STATUS)
                tp->last_tag = sblk->status_tag;
        rmb();
+       sblk->status &= ~SD_STATUS_UPDATED;
 
        /* if no more work, tell net stack and NIC we're done */
        done = !tg3_has_work(tp);
@@ -2964,6 +2965,7 @@ static irqreturn_t tg3_msi(int irq, void *dev_id, struct pt_regs *regs)
         */
        tw32_mailbox(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
        tp->last_tag = sblk->status_tag;
+       rmb();
        sblk->status &= ~SD_STATUS_UPDATED;
        if (likely(tg3_has_work(tp)))
                netif_rx_schedule(dev);         /* schedule NAPI poll */
@@ -3051,6 +3053,7 @@ 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();
                sblk->status &= ~SD_STATUS_UPDATED;
                if (likely(tg3_has_work(tp)))
                        netif_rx_schedule(dev);         /* schedule NAPI poll */