Documentation/DMA-API-HOWTO.txt states:
"DMA transfers need to be synced properly in order for
the cpu and device to see the most uptodate and correct
copy of the DMA buffer."
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx>
---
Embarrassingly, this bug is unique to p54 and has been around
since 2.6.25. This tells us something interesting about our
userbase.
---
diff --git a/drivers/net/wireless/p54/p54pci.c b/drivers/net/wireless/p54/p54pci.c
index 1eacba4..0494d7b 100644
--- a/drivers/net/wireless/p54/p54pci.c
+++ b/drivers/net/wireless/p54/p54pci.c
@@ -199,6 +199,7 @@ static void p54p_check_rx_ring(struct ieee80211_hw *dev, u32 *index,
while (i != idx) {
u16 len;
struct sk_buff *skb;
+ dma_addr_t dma_addr;
desc = &ring[i];
len = le16_to_cpu(desc->len);
skb = rx_buf[i];
@@ -216,17 +217,20 @@ static void p54p_check_rx_ring(struct ieee80211_hw *dev, u32 *index,
len = priv->common.rx_mtu;
}
+ dma_addr = le32_to_cpu(desc->host_addr);
+ pci_dma_sync_single_for_cpu(priv->pdev, dma_addr,
+ priv->common.rx_mtu + 32, PCI_DMA_FROMDEVICE);
skb_put(skb, len);
if (p54_rx(dev, skb)) {
- pci_unmap_single(priv->pdev,
- le32_to_cpu(desc->host_addr),
- priv->common.rx_mtu + 32,
- PCI_DMA_FROMDEVICE);
+ pci_unmap_single(priv->pdev, dma_addr,
+ priv->common.rx_mtu + 32, PCI_DMA_FROMDEVICE);
rx_buf[i] = NULL;
- desc->host_addr = 0;
+ desc->host_addr = cpu_to_le32(0);
} else {
skb_trim(skb, 0);
+ pci_dma_sync_single_for_device(priv->pdev, dma_addr,
+ priv->common.rx_mtu + 32, PCI_DMA_FROMDEVICE);
desc->len = cpu_to_le16(priv->common.rx_mtu + 32);
}
--
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