ravb: fix ring memory allocation

The driver is written as if it can adapt to a low memory situation  allocating
less RX  skbs and TX aligned buffers than the respective RX/TX ring sizes.  In
reality  though  the driver  would malfunction in this case. Stop being overly
smart and just fail in such situation -- this is achieved by moving the memory
allocation from ravb_ring_format() to ravb_ring_init().

We leave dma_map_single() calls in place but make their failure non-fatal
by marking the corresponding RX descriptors  with zero data size which should
prevent DMA to an invalid addresses.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 25 deletions

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index d08c250e843e..78849dd4ef8e 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -228,9 +228,7 @@ static void ravb_ring_format(struct net_device *ndev, int q)
         struct ravb_desc *desc = NULL;
         int rx_ring_size = sizeof(*rx_desc) * priv->num_rx_ring[q];
         int tx_ring_size = sizeof(*tx_desc) * priv->num_tx_ring[q];
-        struct sk_buff *skb;
         dma_addr_t dma_addr;
-        void *buffer;
         int i;
 
         priv->cur_rx[q] = 0;
@@ -241,41 +239,28 @@ static void ravb_ring_format(struct net_device *ndev, int q)
         memset(priv->rx_ring[q], 0, rx_ring_size);
         /* Build RX ring buffer */
         for (i = 0; i < priv->num_rx_ring[q]; i++) {
-                priv->rx_skb[q][i] = NULL;
-                skb = netdev_alloc_skb(ndev, PKT_BUF_SZ + RAVB_ALIGN - 1);
-                if (!skb)
-                        break;
-                ravb_set_buffer_align(skb);
                 /* RX descriptor */
                 rx_desc = &priv->rx_ring[q][i];
                 /* The size of the buffer should be on 16-byte boundary. */
                 rx_desc->ds_cc = cpu_to_le16(ALIGN(PKT_BUF_SZ, 16));
-                dma_addr = dma_map_single(&ndev->dev, skb->data,
+                dma_addr = dma_map_single(&ndev->dev, priv->rx_skb[q][i]->data,
                                           ALIGN(PKT_BUF_SZ, 16),
                                           DMA_FROM_DEVICE);
-                if (dma_mapping_error(&ndev->dev, dma_addr)) {
-                        dev_kfree_skb(skb);
-                        break;
-                }
-                priv->rx_skb[q][i] = skb;
+                /* We just set the data size to 0 for a failed mapping which
+                 * should prevent DMA from happening...
+                 */
+                if (dma_mapping_error(&ndev->dev, dma_addr))
+                        rx_desc->ds_cc = cpu_to_le16(0);
                 rx_desc->dptr = cpu_to_le32(dma_addr);
                 rx_desc->die_dt = DT_FEMPTY;
         }
         rx_desc = &priv->rx_ring[q][i];
         rx_desc->dptr = cpu_to_le32((u32)priv->rx_desc_dma[q]);
         rx_desc->die_dt = DT_LINKFIX; /* type */
-        priv->dirty_rx[q] = (u32)(i - priv->num_rx_ring[q]);
 
         memset(priv->tx_ring[q], 0, tx_ring_size);
         /* Build TX ring buffer */
         for (i = 0; i < priv->num_tx_ring[q]; i++) {
-                priv->tx_skb[q][i] = NULL;
-                priv->tx_buffers[q][i] = NULL;
-                buffer = kmalloc(PKT_BUF_SZ + RAVB_ALIGN - 1, GFP_KERNEL);
-                if (!buffer)
-                        break;
-                /* Aligned TX buffer */
-                priv->tx_buffers[q][i] = buffer;
                 tx_desc = &priv->tx_ring[q][i];
                 tx_desc->die_dt = DT_EEMPTY;
         }
@@ -298,7 +283,10 @@ static void ravb_ring_format(struct net_device *ndev, int q)
 static int ravb_ring_init(struct net_device *ndev, int q)
 {
         struct ravb_private *priv = netdev_priv(ndev);
+        struct sk_buff *skb;
         int ring_size;
+        void *buffer;
+        int i;
 
         /* Allocate RX and TX skb rings */
         priv->rx_skb[q] = kcalloc(priv->num_rx_ring[q],
@@ -308,12 +296,28 @@ static int ravb_ring_init(struct net_device *ndev, int q)
         if (!priv->rx_skb[q] || !priv->tx_skb[q])
                 goto error;
 
+        for (i = 0; i < priv->num_rx_ring[q]; i++) {
+                skb = netdev_alloc_skb(ndev, PKT_BUF_SZ + RAVB_ALIGN - 1);
+                if (!skb)
+                        goto error;
+                ravb_set_buffer_align(skb);
+                priv->rx_skb[q][i] = skb;
+        }
+
         /* Allocate rings for the aligned buffers */
         priv->tx_buffers[q] = kcalloc(priv->num_tx_ring[q],
                                       sizeof(*priv->tx_buffers[q]), GFP_KERNEL);
         if (!priv->tx_buffers[q])
                 goto error;
 
+        for (i = 0; i < priv->num_tx_ring[q]; i++) {
+                buffer = kmalloc(PKT_BUF_SZ + RAVB_ALIGN - 1, GFP_KERNEL);
+                if (!buffer)
+                        goto error;
+                /* Aligned TX buffer */
+                priv->tx_buffers[q][i] = buffer;
+        }
+
         /* Allocate all RX descriptors. */
         ring_size = sizeof(struct ravb_ex_rx_desc) * (priv->num_rx_ring[q] + 1);
         priv->rx_ring[q] = dma_alloc_coherent(NULL, ring_size,
@@ -524,6 +528,10 @@ static bool ravb_rx(struct net_device *ndev, int *quota, int q)
                 if (--boguscnt < 0)
                         break;
 
+                /* We use 0-byte descriptors to mark the DMA mapping errors */
+                if (!pkt_len)
+                        continue;
+
                 if (desc_status & MSC_MC)
                         stats->multicast++;
 
@@ -587,10 +595,11 @@ static bool ravb_rx(struct net_device *ndev, int *quota, int q)
                                                   le16_to_cpu(desc->ds_cc),
                                                   DMA_FROM_DEVICE);
                         skb_checksum_none_assert(skb);
-                        if (dma_mapping_error(&ndev->dev, dma_addr)) {
-                                dev_kfree_skb_any(skb);
-                                break;
-                        }
+                        /* We just set the data size to 0 for a failed mapping
+                         * which should prevent DMA  from happening...
+                         */
+                        if (dma_mapping_error(&ndev->dev, dma_addr))
+                                desc->ds_cc = cpu_to_le16(0);
                         desc->dptr = cpu_to_le32(dma_addr);
                         priv->rx_skb[q][entry] = skb;
                 }