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authorEric Dumazet <edumazet@google.com>2012-05-18 05:12:12 +0000
committerDavid S. Miller <davem@davemloft.net>2012-05-18 13:31:25 -0400
commit6f532612cc2410a5079ea0f83e7a5011adfbf70d (patch)
tree0459fada6287120f5c47ed56c440c4d1c3e3eaa2 /net
parent56138f50d1900b0c3d8647376e37b488b23ba53d (diff)
downloadlinux-6f532612cc2410a5079ea0f83e7a5011adfbf70d.tar.gz
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>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c82
1 files changed, 41 insertions, 41 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7645df1bada..7ceb673d622 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -300,6 +300,40 @@ struct netdev_alloc_cache {
static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
/**
+ * netdev_alloc_frag - allocate a page fragment
+ * @fragsz: fragment size
+ *
+ * Allocates a frag from a page for receive buffer.
+ * Uses GFP_ATOMIC allocations.
+ */
+void *netdev_alloc_frag(unsigned int fragsz)
+{
+ struct netdev_alloc_cache *nc;
+ void *data = NULL;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ nc = &__get_cpu_var(netdev_alloc_cache);
+ if (unlikely(!nc->page)) {
+refill:
+ nc->page = alloc_page(GFP_ATOMIC | __GFP_COLD);
+ nc->offset = 0;
+ }
+ if (likely(nc->page)) {
+ if (nc->offset + fragsz > PAGE_SIZE) {
+ put_page(nc->page);
+ goto refill;
+ }
+ data = page_address(nc->page) + nc->offset;
+ nc->offset += fragsz;
+ get_page(nc->page);
+ }
+ local_irq_restore(flags);
+ return data;
+}
+EXPORT_SYMBOL(netdev_alloc_frag);
+
+/**
* __netdev_alloc_skb - allocate an skbuff for rx on a specific device
* @dev: network device to receive on
* @length: length to allocate
@@ -313,32 +347,20 @@ static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
* %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)
+ unsigned int length, gfp_t gfp_mask)
{
- struct sk_buff *skb;
+ struct sk_buff *skb = NULL;
unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
if (fragsz <= PAGE_SIZE && !(gfp_mask & __GFP_WAIT)) {
- struct netdev_alloc_cache *nc;
- void *data = NULL;
+ void *data = netdev_alloc_frag(fragsz);
- nc = &get_cpu_var(netdev_alloc_cache);
- if (!nc->page) {
-refill: nc->page = alloc_page(gfp_mask);
- nc->offset = 0;
- }
- if (likely(nc->page)) {
- if (nc->offset + fragsz > PAGE_SIZE) {
- put_page(nc->page);
- goto refill;
- }
- data = page_address(nc->page) + nc->offset;
- nc->offset += fragsz;
- get_page(nc->page);
+ if (likely(data)) {
+ skb = build_skb(data, fragsz);
+ if (unlikely(!skb))
+ put_page(virt_to_head_page(data));
}
- put_cpu_var(netdev_alloc_cache);
- skb = data ? build_skb(data, fragsz) : NULL;
} else {
skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
}
@@ -360,28 +382,6 @@ void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
}
EXPORT_SYMBOL(skb_add_rx_frag);
-/**
- * dev_alloc_skb - allocate an skbuff for receiving
- * @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.
- */
-struct sk_buff *dev_alloc_skb(unsigned int length)
-{
- /*
- * There is more code here than it seems:
- * __dev_alloc_skb is an inline
- */
- return __dev_alloc_skb(length, GFP_ATOMIC);
-}
-EXPORT_SYMBOL(dev_alloc_skb);
-
static void skb_drop_list(struct sk_buff **listp)
{
struct sk_buff *list = *listp;