net: ep93xx_eth: fix DMA API violations
Russell King said: > > So, to summarize what its doing: > > 1. It allocates buffers for rx and tx. > 2. It maps them with dma_map_single(). > This transfers ownership of the buffer to the DMA device. > 3. In ep93xx_xmit, > 3a. It copies the data into the buffer with skb_copy_and_csum_dev() > This violates the DMA buffer ownership rules - the CPU should > not be writing to this buffer while it is (in principle) owned > by the DMA device. > 3b. It then calls dma_sync_single_for_cpu() for the buffer. > This transfers ownership of the buffer to the CPU, which surely > is the wrong direction. > 4. In ep93xx_rx, > 4a. It calls dma_sync_single_for_cpu() for the buffer. > This at least transfers the DMA buffer ownership to the CPU > before the CPU reads the buffer > 4b. It then uses skb_copy_to_linear_data() to copy the data out. > At no point does it transfer ownership back to the DMA device. > 5. When the driver is removed, it dma_unmap_single()'s the buffer. > This transfers ownership of the buffer to the CPU. > 6. It frees the buffer. > > While it may work on ep93xx, it's not respecting the DMA API rules, > and with DMA debugging enabled it will probably encounter quite a few > warnings. This patch fixes these violations. Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com> Tested-by: Petr Stetiar <ynezz@true.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
1f758a4341
commit
f1c089e319
|
@ -283,10 +283,14 @@ static int ep93xx_rx(struct net_device *dev, int processed, int budget)
|
|||
|
||||
skb = dev_alloc_skb(length + 2);
|
||||
if (likely(skb != NULL)) {
|
||||
struct ep93xx_rdesc *rxd = &ep->descs->rdesc[entry];
|
||||
skb_reserve(skb, 2);
|
||||
dma_sync_single_for_cpu(dev->dev.parent, ep->descs->rdesc[entry].buf_addr,
|
||||
dma_sync_single_for_cpu(dev->dev.parent, rxd->buf_addr,
|
||||
length, DMA_FROM_DEVICE);
|
||||
skb_copy_to_linear_data(skb, ep->rx_buf[entry], length);
|
||||
dma_sync_single_for_device(dev->dev.parent,
|
||||
rxd->buf_addr, length,
|
||||
DMA_FROM_DEVICE);
|
||||
skb_put(skb, length);
|
||||
skb->protocol = eth_type_trans(skb, dev);
|
||||
|
||||
|
@ -348,6 +352,7 @@ poll_some_more:
|
|||
static int ep93xx_xmit(struct sk_buff *skb, struct net_device *dev)
|
||||
{
|
||||
struct ep93xx_priv *ep = netdev_priv(dev);
|
||||
struct ep93xx_tdesc *txd;
|
||||
int entry;
|
||||
|
||||
if (unlikely(skb->len > MAX_PKT_SIZE)) {
|
||||
|
@ -359,11 +364,14 @@ static int ep93xx_xmit(struct sk_buff *skb, struct net_device *dev)
|
|||
entry = ep->tx_pointer;
|
||||
ep->tx_pointer = (ep->tx_pointer + 1) & (TX_QUEUE_ENTRIES - 1);
|
||||
|
||||
ep->descs->tdesc[entry].tdesc1 =
|
||||
TDESC1_EOF | (entry << 16) | (skb->len & 0xfff);
|
||||
txd = &ep->descs->tdesc[entry];
|
||||
|
||||
txd->tdesc1 = TDESC1_EOF | (entry << 16) | (skb->len & 0xfff);
|
||||
dma_sync_single_for_cpu(dev->dev.parent, txd->buf_addr, skb->len,
|
||||
DMA_TO_DEVICE);
|
||||
skb_copy_and_csum_dev(skb, ep->tx_buf[entry]);
|
||||
dma_sync_single_for_cpu(dev->dev.parent, ep->descs->tdesc[entry].buf_addr,
|
||||
skb->len, DMA_TO_DEVICE);
|
||||
dma_sync_single_for_device(dev->dev.parent, txd->buf_addr, skb->len,
|
||||
DMA_TO_DEVICE);
|
||||
dev_kfree_skb(skb);
|
||||
|
||||
spin_lock_irq(&ep->tx_pending_lock);
|
||||
|
|
Loading…
Reference in New Issue