[NET]: Fix NAPI completion handling in some drivers.

In order for the list handling in net_rx_action() to be
correct, drivers must follow certain rules as stated by
this comment in net_rx_action():

		/* Drivers must not modify the NAPI state if they
		 * consume the entire weight.  In such cases this code
		 * still "owns" the NAPI instance and therefore can
		 * move the instance around on the list at-will.
		 */

A few drivers do not do this because they mix the budget checks
with reading hardware state, resulting in crashes like the one
reported by takano@axe-inc.co.jp.

BNX2 and TG3 are taken care of here, SKY2 fix is from Stephen
Hemminger.
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bnx2.c

@@ -2633,15 +2633,11 @@ bnx2_has_work(struct bnx2 *bp)
 	return 0;
 }
 
-static int
-bnx2_poll(struct napi_struct *napi, int budget)
+static int bnx2_poll_work(struct bnx2 *bp, int work_done, int budget)
 {
-	struct bnx2 *bp = container_of(napi, struct bnx2, napi);
-	struct net_device *dev = bp->dev;
 	struct status_block *sblk = bp->status_blk;
 	u32 status_attn_bits = sblk->status_attn_bits;
 	u32 status_attn_bits_ack = sblk->status_attn_bits_ack;
-	int work_done = 0;
 
 	if ((status_attn_bits & STATUS_ATTN_EVENTS) !=
 	    (status_attn_bits_ack & STATUS_ATTN_EVENTS)) {
@@ -2660,13 +2656,27 @@ bnx2_poll(struct napi_struct *napi, int budget)
 		bnx2_tx_int(bp);
 
 	if (bp->status_blk->status_rx_quick_consumer_index0 != bp->hw_rx_cons)
-		work_done = bnx2_rx_int(bp, budget);
+		work_done += bnx2_rx_int(bp, budget - work_done);
+
+	return work_done;
+}
+
+static int bnx2_poll(struct napi_struct *napi, int budget)
+{
+	struct bnx2 *bp = container_of(napi, struct bnx2, napi);
+	int work_done = 0;
+
+	while (1) {
+		work_done = bnx2_poll_work(bp, work_done, budget);
 
+		if (unlikely(work_done >= budget))
+			break;
+
+		if (likely(!bnx2_has_work(bp))) {
 			bp->last_status_idx = bp->status_blk->status_idx;
 			rmb();
 
-	if (!bnx2_has_work(bp)) {
-		netif_rx_complete(dev, napi);
+			netif_rx_complete(bp->dev, napi);
 			if (likely(bp->flags & USING_MSI_FLAG)) {
 				REG_WR(bp, BNX2_PCICFG_INT_ACK_CMD,
 				       BNX2_PCICFG_INT_ACK_CMD_INDEX_VALID |
@@ -2681,6 +2691,8 @@ bnx2_poll(struct napi_struct *napi, int budget)
 			REG_WR(bp, BNX2_PCICFG_INT_ACK_CMD,
 			       BNX2_PCICFG_INT_ACK_CMD_INDEX_VALID |
 			       bp->last_status_idx);
+			break;
+		}
 	}
 
 	return work_done;

drivers/net/sky2.c

@@ -2606,7 +2606,7 @@ static int sky2_poll(struct napi_struct *napi, int work_limit)
 {
 	struct sky2_hw *hw = container_of(napi, struct sky2_hw, napi);
 	u32 status = sky2_read32(hw, B0_Y2_SP_EISR);
-	int work_done;
+	int work_done = 0;
 
 	if (unlikely(status & Y2_IS_ERROR))
 		sky2_err_intr(hw, status);
@@ -2617,10 +2617,16 @@ static int sky2_poll(struct napi_struct *napi, int work_limit)
 	if (status & Y2_IS_IRQ_PHY2)
 		sky2_phy_intr(hw, 1);
 
-	work_done = sky2_status_intr(hw, work_limit);
+	for(;;) {
+		work_done += sky2_status_intr(hw, work_limit);
+
+		if (work_done >= work_limit)
+			break;
 
 		/* More work? */
-	if (hw->st_idx == sky2_read16(hw, STAT_PUT_IDX)) {
+		if (hw->st_idx != sky2_read16(hw, STAT_PUT_IDX))
+			continue;
+
 		/* Bug/Errata workaround?
 		 * Need to kick the TX irq moderation timer.
 		 */
@@ -2631,7 +2637,10 @@ static int sky2_poll(struct napi_struct *napi, int work_limit)
 
 		napi_complete(napi);
 		sky2_read32(hw, B0_Y2_SP_LISR);
+		break;
+
 	}
+
 	return work_done;
 }
 

drivers/net/tg3.c

@@ -3555,12 +3555,9 @@ static int tg3_rx(struct tg3 *tp, int budget)
 	return received;
 }
 
-static int tg3_poll(struct napi_struct *napi, int budget)
+static int tg3_poll_work(struct tg3 *tp, int work_done, int budget)
 {
-	struct tg3 *tp = container_of(napi, struct tg3, napi);
-	struct net_device *netdev = tp->dev;
 	struct tg3_hw_status *sblk = tp->hw_status;
-	int work_done = 0;
 
 	/* handle link change and other phy events */
 	if (!(tp->tg3_flags &
@@ -3578,19 +3575,36 @@ static int tg3_poll(struct napi_struct *napi, int budget)
 	/* run TX completion thread */
 	if (sblk->idx[0].tx_consumer != tp->tx_cons) {
 		tg3_tx(tp);
-		if (unlikely(tp->tg3_flags & TG3_FLAG_TX_RECOVERY_PENDING)) {
-			netif_rx_complete(netdev, napi);
-			schedule_work(&tp->reset_task);
+		if (unlikely(tp->tg3_flags & TG3_FLAG_TX_RECOVERY_PENDING))
 			return 0;
 	}
-	}
 
 	/* run RX thread, within the bounds set by NAPI.
 	 * All RX "locking" is done by ensuring outside
 	 * code synchronizes with tg3->napi.poll()
 	 */
 	if (sblk->idx[0].rx_producer != tp->rx_rcb_ptr)
-		work_done = tg3_rx(tp, budget);
+		work_done += tg3_rx(tp, budget - work_done);
+
+	return work_done;
+}
+
+static int tg3_poll(struct napi_struct *napi, int budget)
+{
+	struct tg3 *tp = container_of(napi, struct tg3, napi);
+	int work_done = 0;
+
+	while (1) {
+		work_done = tg3_poll_work(tp, work_done, budget);
+
+		if (unlikely(tp->tg3_flags & TG3_FLAG_TX_RECOVERY_PENDING))
+			goto tx_recovery;
+
+		if (unlikely(work_done >= budget))
+			break;
+
+		if (likely(!tg3_has_work(tp))) {
+			struct tg3_hw_status *sblk = tp->hw_status;
 
 			if (tp->tg3_flags & TG3_FLAG_TAGGED_STATUS) {
 				tp->last_tag = sblk->status_tag;
@@ -3598,13 +3612,18 @@ static int tg3_poll(struct napi_struct *napi, int budget)
 			} else
 				sblk->status &= ~SD_STATUS_UPDATED;
 
-	/* if no more work, tell net stack and NIC we're done */
-	if (!tg3_has_work(tp)) {
-		netif_rx_complete(netdev, napi);
+			netif_rx_complete(tp->dev, napi);
 			tg3_restart_ints(tp);
+			break;
+		}
 	}
 
 	return work_done;
+
+tx_recovery:
+	netif_rx_complete(tp->dev, napi);
+	schedule_work(&tp->reset_task);
+	return 0;
 }
 
 static void tg3_irq_quiesce(struct tg3 *tp)