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Message-ID: <1836998.fscmK2EJWV@wasted.cogentembedded.com>
Date: Wed, 22 Jul 2015 01:31:59 +0300
From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To: netdev@...r.kernel.org
Cc: linux-sh@...r.kernel.org
Subject: [PATCH] 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@...entembedded.com>
---
The patch is against Dave Miller's 'net.git' repo.
drivers/net/ethernet/renesas/ravb_main.c | 59 +++++++++++++++++--------------
1 file changed, 34 insertions(+), 25 deletions(-)
Index: net/drivers/net/ethernet/renesas/ravb_main.c
===================================================================
--- net.orig/drivers/net/ethernet/renesas/ravb_main.c
+++ net/drivers/net/ethernet/renesas/ravb_main.c
@@ -228,9 +228,7 @@ static void ravb_ring_format(struct net_
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_
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_
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_dev
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 *n
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 *n
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;
}
--
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