From 6f532612cc2410a5079ea0f83e7a5011adfbf70d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 18 May 2012 05:12:12 +0000 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- 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 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) { diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 7645df1bada0..7ceb673d622f 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -299,6 +299,40 @@ 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 @@ -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; -- 2.20.1