e1000e: fix dma error handling issues

There were a few issues I noticed in e1000e. These include a double free
of the skb if mapping fails, and the fact that context descriptors appear
to be left in the descriptor ring after the failure.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 44 deletions

diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index 402d2dd7d68f..da876d59a9ca 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -574,6 +574,7 @@ static void e1000_put_txbuf(struct e1000_adapter *adapter,
                 dev_kfree_skb_any(buffer_info->skb);
                 buffer_info->skb = NULL;
         }
+        buffer_info->time_stamp = 0;
 }
 
 static void e1000_print_tx_hang(struct e1000_adapter *adapter)
@@ -678,17 +679,10 @@ static bool e1000_clean_tx_irq(struct e1000_adapter *adapter)
         }
 
         if (adapter->detect_tx_hung) {
-                /*
-                 * Detect a transmit hang in hardware, this serializes the
-                 * check with the clearing of time_stamp and movement of i
-                 */
+                /* Detect a transmit hang in hardware, this serializes the
+                 * check with the clearing of time_stamp and movement of i */
                 adapter->detect_tx_hung = 0;
-                /*
-                 * read barrier to make sure that the ->dma member and time
-                 * stamp are updated fully
-                 */
-                smp_rmb();
-                if (tx_ring->buffer_info[eop].dma &&
+                if (tx_ring->buffer_info[eop].time_stamp &&
                     time_after(jiffies, tx_ring->buffer_info[eop].time_stamp
                                + (adapter->tx_timeout_factor * HZ))
                     && !(er32(STATUS) & E1000_STATUS_TXOFF)) {
@@ -3824,39 +3818,41 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
                         unsigned int mss)
 {
         struct e1000_ring *tx_ring = adapter->tx_ring;
+        struct e1000_buffer *buffer_info;
         unsigned int len = skb_headlen(skb);
         unsigned int offset, size, count = 0, i;
         unsigned int f;
-        dma_addr_t map;
+        dma_addr_t *map;
 
         i = tx_ring->next_to_use;
 
         if (skb_dma_map(&adapter->pdev->dev, skb, DMA_TO_DEVICE)) {
                 dev_err(&adapter->pdev->dev, "TX DMA map failed\n");
                 adapter->tx_dma_failed++;
-                dev_kfree_skb(skb);
-                return -2;
+                return 0;
         }
 
-        map = skb_shinfo(skb)->dma_maps[0];
+        map = skb_shinfo(skb)->dma_maps;
         offset = 0;
 
         while (len) {
-                struct e1000_buffer *buffer_info = &tx_ring->buffer_info[i];
+                buffer_info = &tx_ring->buffer_info[i];
                 size = min(len, max_per_txd);
 
                 buffer_info->length = size;
-                /* set time_stamp *before* dma to help avoid a possible race */
                 buffer_info->time_stamp = jiffies;
-                buffer_info->dma = map + offset;
                 buffer_info->next_to_watch = i;
+                buffer_info->dma = map[0] + offset;
+                count++;
 
                 len -= size;
                 offset += size;
-                count++;
-                i++;
-                if (i == tx_ring->count)
-                        i = 0;
+
+                if (len) {
+                        i++;
+                        if (i == tx_ring->count)
+                                i = 0;
+                }
         }
 
         for (f = 0; f < nr_frags; f++) {
@@ -3864,37 +3860,29 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
 
                 frag = &skb_shinfo(skb)->frags[f];
                 len = frag->size;
-                map = skb_shinfo(skb)->dma_maps[f + 1];
                 offset = 0;
 
                 while (len) {
-                        struct e1000_buffer *buffer_info;
+                        i++;
+                        if (i == tx_ring->count)
+                                i = 0;
+
                         buffer_info = &tx_ring->buffer_info[i];
                         size = min(len, max_per_txd);
 
                         buffer_info->length = size;
                         buffer_info->time_stamp = jiffies;
-                        buffer_info->dma = map + offset;
                         buffer_info->next_to_watch = i;
+                        buffer_info->dma = map[f + 1] + offset;
 
                         len -= size;
                         offset += size;
                         count++;
-
-                        i++;
-                        if (i == tx_ring->count)
-                                i = 0;
                 }
         }
 
-        if (i == 0)
-                i = tx_ring->count - 1;
-        else
-                i--;
-
         tx_ring->buffer_info[i].skb = skb;
         tx_ring->buffer_info[first].next_to_watch = i;
-        smp_wmb();
 
         return count;
 }
@@ -4145,20 +4133,20 @@ static int e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
         if (skb->protocol == htons(ETH_P_IP))
                 tx_flags |= E1000_TX_FLAGS_IPV4;
 
+        /* if count is 0 then mapping error has occured */
         count = e1000_tx_map(adapter, skb, first, max_per_txd, nr_frags, mss);
-        if (count < 0) {
-                /* handle pci_map_single() error in e1000_tx_map */
+        if (count) {
+                e1000_tx_queue(adapter, tx_flags, count);
+                netdev->trans_start = jiffies;
+                /* Make sure there is space in the ring for the next send. */
+                e1000_maybe_stop_tx(netdev, MAX_SKB_FRAGS + 2);
+
+        } else {
                 dev_kfree_skb_any(skb);
-                return NETDEV_TX_OK;
+                tx_ring->buffer_info[first].time_stamp = 0;
+                tx_ring->next_to_use = first;
         }
 
-        e1000_tx_queue(adapter, tx_flags, count);
-
-        netdev->trans_start = jiffies;
-
-        /* Make sure there is space in the ring for the next send. */
-        e1000_maybe_stop_tx(netdev, MAX_SKB_FRAGS + 2);
-
         return NETDEV_TX_OK;
 }