[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>

3 files changed, 82 insertions, 42 deletions

diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
index bbfbdafb4ae5..d68accea380b 100644
--- a/drivers/net/bnx2.c
+++ b/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)) {
@@ -2660,27 +2656,43 @@ 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);
 
-        bp->last_status_idx = bp->status_blk->status_idx;
-        rmb();
+        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 (!bnx2_has_work(bp)) {
-                netif_rx_complete(dev, napi);
-                if (likely(bp->flags & USING_MSI_FLAG)) {
+                if (unlikely(work_done >= budget))
+                        break;
+
+                if (likely(!bnx2_has_work(bp))) {
+                        bp->last_status_idx = bp->status_blk->status_idx;
+                        rmb();
+
+                        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 |
+                                       bp->last_status_idx);
+                                return 0;
+                        }
                         REG_WR(bp, BNX2_PCICFG_INT_ACK_CMD,
                                BNX2_PCICFG_INT_ACK_CMD_INDEX_VALID |
+                               BNX2_PCICFG_INT_ACK_CMD_MASK_INT |
                                bp->last_status_idx);
-                        return 0;
-                }
-                REG_WR(bp, BNX2_PCICFG_INT_ACK_CMD,
-                       BNX2_PCICFG_INT_ACK_CMD_INDEX_VALID |
-                       BNX2_PCICFG_INT_ACK_CMD_MASK_INT |
-                       bp->last_status_idx);
 
-                REG_WR(bp, BNX2_PCICFG_INT_ACK_CMD,
-                       BNX2_PCICFG_INT_ACK_CMD_INDEX_VALID |
-                       bp->last_status_idx);
+                        REG_WR(bp, BNX2_PCICFG_INT_ACK_CMD,
+                               BNX2_PCICFG_INT_ACK_CMD_INDEX_VALID |
+                               bp->last_status_idx);
+                        break;
+                }
         }
 
         return work_done;
diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index fe0e7560d236..4e569fa0f96c 100644
--- a/drivers/net/sky2.c
+++ b/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))
+                        continue;
 
-        /* More work? */
-        if (hw->st_idx == sky2_read16(hw, STAT_PUT_IDX)) {
                 /* 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;
 }
 
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index d2b30fb0b318..a402b5c01896 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -3555,12 +3555,9 @@ next_pkt_nopost:
         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 &
@@ -3578,11 +3575,8 @@ 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.
@@ -3590,21 +3584,46 @@ static int tg3_poll(struct napi_struct *napi, int budget)
          * 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);
 
-        if (tp->tg3_flags & TG3_FLAG_TAGGED_STATUS) {
-                tp->last_tag = sblk->status_tag;
-                rmb();
-        } else
-                sblk->status &= ~SD_STATUS_UPDATED;
+        return work_done;
+}
 
-        /* if no more work, tell net stack and NIC we're done */
-        if (!tg3_has_work(tp)) {
-                netif_rx_complete(netdev, napi);
-                tg3_restart_ints(tp);
+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;
+                                rmb();
+                        } else
+                                sblk->status &= ~SD_STATUS_UPDATED;
+
+                        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)