skbuff: remove skb_dma_map/unmap

The two functions skb_dma_map/unmap are unsafe to use as they cause
problems when packets are cloned and sent to multiple devices while a HW
IOMMU is enabled.  Due to this it is best to remove the code so it is not
used by any other network driver maintainters.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -416,14 +416,6 @@ struct sk_buff {
 
 #include <asm/system.h>
 
-#ifdef CONFIG_HAS_DMA
-#include <linux/dma-mapping.h>
-extern int skb_dma_map(struct device *dev, struct sk_buff *skb,
-		       enum dma_data_direction dir);
-extern void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
-			  enum dma_data_direction dir);
-#endif
-
 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
 {
 	return (struct dst_entry *)skb->_skb_dst;

net/core/Makefile

@@ -6,7 +6,6 @@ obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \
 	 gen_stats.o gen_estimator.o net_namespace.o
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
-obj-$(CONFIG_HAS_DMA) += skb_dma_map.o
 
 obj-y		     += dev.o ethtool.o dev_mcast.o dst.o netevent.o \
 			neighbour.o rtnetlink.o utils.o link_watch.o filter.o