net: introduce netdev_alloc_frag()

Fix two issues introduced in commit a1c7fff7e18f5
( net: netdev_alloc_skb() use build_skb() )

- Must be IRQ safe (non NAPI drivers can use it)
- Must not leak the frag if build_skb() fails to allocate sk_buff

This patch introduces netdev_alloc_frag() for drivers willing to
use build_skb() instead of __netdev_alloc_skb() variants.

Factorize code so that :
__dev_alloc_skb() is a wrapper around __netdev_alloc_skb(), and
dev_alloc_skb() a wrapper around netdev_alloc_skb()

Use __GFP_COLD flag.

Almost all network drivers now benefit from skb->head_frag
infrastructure.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 24 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb47314c7179..fe37c21d3a60 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1680,31 +1680,11 @@ static inline void __skb_queue_purge(struct sk_buff_head *list)
                 kfree_skb(skb);
 }
 
-/**
- *      __dev_alloc_skb - allocate an skbuff for receiving
- *      @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.
- */
-static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
-                                              gfp_t gfp_mask)
-{
-        struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
-        if (likely(skb))
-                skb_reserve(skb, NET_SKB_PAD);
-        return skb;
-}
-
-extern struct sk_buff *dev_alloc_skb(unsigned int length);
+extern void *netdev_alloc_frag(unsigned int fragsz);
 
 extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
-                unsigned int length, gfp_t gfp_mask);
+                                          unsigned int length,
+                                          gfp_t gfp_mask);
 
 /**
  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
@@ -1720,11 +1700,25 @@ extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
  *      allocates memory it can be called from an interrupt.
  */
 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
-                unsigned int length)
+                                               unsigned int length)
 {
         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
 }
 
+/* legacy helper around __netdev_alloc_skb() */
+static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
+                                              gfp_t gfp_mask)
+{
+        return __netdev_alloc_skb(NULL, length, gfp_mask);
+}
+
+/* legacy helper around netdev_alloc_skb() */
+static inline struct sk_buff *dev_alloc_skb(unsigned int length)
+{
+        return netdev_alloc_skb(NULL, length);
+}
+
+
 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
                 unsigned int length, gfp_t gfp)
 {