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Message-ID: <1337353932.7029.34.camel@edumazet-glaptop>
Date: Fri, 18 May 2012 17:12:12 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] net: introduce netdev_alloc_frag()
From: Eric Dumazet <edumazet@...gle.com>
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@...gle.com>
---
include/linux/skbuff.h | 42 ++++++++-----------
net/core/skbuff.c | 82 +++++++++++++++++++--------------------
2 files changed, 59 insertions(+), 65 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb47314..fe37c21 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)
{
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7645df1..f0bcbe6 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;
--
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