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net: change illegal_highdma to use dma_mask

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Robert Hancock pointed out two problems about NETIF_F_HIGHDMA:

-Many drivers only set the flag when they detect they can use 64-bit DMA,
since otherwise they could receive DMA addresses that they can't handle
(which on platforms without IOMMU/SWIOTLB support is fatal). This means that if
64-bit support isn't available, even buffers located below 4GB will get copied
unnecessarily.

-Some drivers set the flag even though they can't actually handle 64-bit DMA,
which would mean that on platforms without IOMMU/SWIOTLB they would get a DMA
mapping error if the memory they received happened to be located above 4GB.

http://lkml.org/lkml/2010/3/3/530

We can use the dma_mask if we need bouncing or not here. Then we can
safely fix drivers that misuse NETIF_F_HIGHDMA.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
FUJITA Tomonori 2010-03-30 22:35:50 +00:00 committed by David S. Miller
parent 4fd89b7af2
commit 5acbbd428d
1 changed files with 14 additions and 6 deletions
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20
net/core/dev.c
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@ -129,6 +129,7 @@
#include <linux/jhash.h>
#include <linux/random.h>
#include <trace/events/napi.h>
#include <linux/pci.h>
#include "net-sysfs.h"
@ -1804,14 +1805,21 @@ static inline int illegal_highdma(struct net_device *dev, struct sk_buff *skb)
{
#ifdef CONFIG_HIGHMEM
int i;
if (!(dev->features & NETIF_F_HIGHDMA)) {
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
if (PageHighMem(skb_shinfo(skb)->frags[i].page))
return 1;
}
if (dev->features & NETIF_F_HIGHDMA)
return 0;
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
if (PageHighMem(skb_shinfo(skb)->frags[i].page))
return 1;
if (PCI_DMA_BUS_IS_PHYS) {
struct device *pdev = dev->dev.parent;
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
dma_addr_t addr = page_to_phys(skb_shinfo(skb)->frags[i].page);
if (!pdev->dma_mask || addr + PAGE_SIZE - 1 > *pdev->dma_mask)
return 1;
}
}
#endif
return 0;
}