Ok, here is the patch I came up with as a result of this thread.
Michael stated he would investigate using a pure tag comparison in
place of tg3_has_work() when the chip is using tagged interrupts.
Thanks.
[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@xxxxxxxxxxxxx>
--- 1/drivers/net/tg3.c.~1~ 2005-06-21 16:39:19.000000000 -0700
+++ 2/drivers/net/tg3.c 2005-06-21 16:47:55.000000000 -0700
@@ -2929,6 +2929,7 @@
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 @@
*/
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 @@
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 */
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