[NET]: Add netdev_alloc_skb().

Add a dev_alloc_skb variant that takes a struct net_device * paramater.
For now that paramater is unused, but I'll use it to allocate the skb
from node-local memory in a follow-up patch.  Also there have been some
other plans mentioned on the list that can use it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 46 insertions, 0 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4307e764ef0a..b91fbfb7d54c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1104,6 +1104,28 @@ static inline struct sk_buff *dev_alloc_skb(unsigned int length)
         return __dev_alloc_skb(length, GFP_ATOMIC);
 }
 
+extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
+                unsigned int length, gfp_t gfp_mask);
+
+/**
+ *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
+ *      @dev: network device to receive on
+ *      @length: length to allocate
+ *
+ *      Allocate a new &sk_buff and assign it a usage count of one. The
+ *      buffer has unspecified headroom built in. Users should allocate
+ *      the headroom they think they need without accounting for the
+ *      built in space. The built in space is used for optimisations.
+ *
+ *      %NULL is returned if there is no free memory. Although this function
+ *      allocates memory it can be called from an interrupt.
+ */
+static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
+                unsigned int length)
+{
+        return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
+}
+
 /**
  *      skb_cow - copy header of skb when it is required
  *      @skb: buffer to cow
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d236f02c6467..71487b915d67 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -256,6 +256,29 @@ nodata:
         goto out;
 }
 
+/**
+ *      __netdev_alloc_skb - allocate an skbuff for rx on a specific device
+ *      @dev: network device to receive on
+ *      @length: length to allocate
+ *      @gfp_mask: get_free_pages mask, passed to alloc_skb
+ *
+ *      Allocate a new &sk_buff and assign it a usage count of one. The
+ *      buffer has unspecified headroom built in. Users should allocate
+ *      the headroom they think they need without accounting for the
+ *      built in space. The built in space is used for optimisations.
+ *
+ *      %NULL is returned if there is no free memory.
+ */
+struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
+                unsigned int length, gfp_t gfp_mask)
+{
+        struct sk_buff *skb;
+
+        skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
+        if (likely(skb))
+                skb_reserve(skb, NET_SKB_PAD);
+        return skb;
+}
 
 static void skb_drop_list(struct sk_buff **listp)
 {
@@ -2048,6 +2071,7 @@ EXPORT_SYMBOL(__kfree_skb);
 EXPORT_SYMBOL(kfree_skb);
 EXPORT_SYMBOL(__pskb_pull_tail);
 EXPORT_SYMBOL(__alloc_skb);
+EXPORT_SYMBOL(__netdev_alloc_skb);
 EXPORT_SYMBOL(pskb_copy);
 EXPORT_SYMBOL(pskb_expand_head);
 EXPORT_SYMBOL(skb_checksum);