net: introduce netdev_alloc_frag()
Fix two issues introduced in commit a1c7fff7e1
( 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>
This commit is contained in:
parent
56138f50d1
commit
6f532612cc
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@ -1680,31 +1680,11 @@ static inline void __skb_queue_purge(struct sk_buff_head *list)
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kfree_skb(skb);
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}
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/**
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* __dev_alloc_skb - allocate an skbuff for receiving
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* @length: length to allocate
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* @gfp_mask: get_free_pages mask, passed to alloc_skb
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*
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* Allocate a new &sk_buff and assign it a usage count of one. The
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* buffer has unspecified headroom built in. Users should allocate
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* the headroom they think they need without accounting for the
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* built in space. The built in space is used for optimisations.
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*
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* %NULL is returned if there is no free memory.
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*/
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static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
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gfp_t gfp_mask)
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{
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struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
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if (likely(skb))
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skb_reserve(skb, NET_SKB_PAD);
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return skb;
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}
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extern struct sk_buff *dev_alloc_skb(unsigned int length);
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extern void *netdev_alloc_frag(unsigned int fragsz);
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extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
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unsigned int length, gfp_t gfp_mask);
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unsigned int length,
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gfp_t gfp_mask);
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/**
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* netdev_alloc_skb - allocate an skbuff for rx on a specific device
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@ -1720,11 +1700,25 @@ extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
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* allocates memory it can be called from an interrupt.
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*/
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static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
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unsigned int length)
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unsigned int length)
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{
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return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
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}
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/* legacy helper around __netdev_alloc_skb() */
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static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
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gfp_t gfp_mask)
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{
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return __netdev_alloc_skb(NULL, length, gfp_mask);
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}
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/* legacy helper around netdev_alloc_skb() */
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static inline struct sk_buff *dev_alloc_skb(unsigned int length)
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{
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return netdev_alloc_skb(NULL, length);
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}
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static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
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unsigned int length, gfp_t gfp)
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{
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@ -299,6 +299,40 @@ struct netdev_alloc_cache {
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};
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static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
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/**
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* netdev_alloc_frag - allocate a page fragment
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* @fragsz: fragment size
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*
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* Allocates a frag from a page for receive buffer.
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* Uses GFP_ATOMIC allocations.
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*/
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void *netdev_alloc_frag(unsigned int fragsz)
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{
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struct netdev_alloc_cache *nc;
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void *data = NULL;
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unsigned long flags;
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local_irq_save(flags);
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nc = &__get_cpu_var(netdev_alloc_cache);
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if (unlikely(!nc->page)) {
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refill:
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nc->page = alloc_page(GFP_ATOMIC | __GFP_COLD);
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nc->offset = 0;
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}
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if (likely(nc->page)) {
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if (nc->offset + fragsz > PAGE_SIZE) {
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put_page(nc->page);
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goto refill;
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}
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data = page_address(nc->page) + nc->offset;
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nc->offset += fragsz;
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get_page(nc->page);
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}
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local_irq_restore(flags);
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return data;
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}
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EXPORT_SYMBOL(netdev_alloc_frag);
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/**
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* __netdev_alloc_skb - allocate an skbuff for rx on a specific device
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* @dev: network device to receive on
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@ -313,32 +347,20 @@ static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
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* %NULL is returned if there is no free memory.
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*/
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struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
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unsigned int length, gfp_t gfp_mask)
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unsigned int length, gfp_t gfp_mask)
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{
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struct sk_buff *skb;
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struct sk_buff *skb = NULL;
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unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) +
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SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
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if (fragsz <= PAGE_SIZE && !(gfp_mask & __GFP_WAIT)) {
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struct netdev_alloc_cache *nc;
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void *data = NULL;
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void *data = netdev_alloc_frag(fragsz);
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nc = &get_cpu_var(netdev_alloc_cache);
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if (!nc->page) {
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refill: nc->page = alloc_page(gfp_mask);
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nc->offset = 0;
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if (likely(data)) {
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skb = build_skb(data, fragsz);
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if (unlikely(!skb))
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put_page(virt_to_head_page(data));
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}
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if (likely(nc->page)) {
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if (nc->offset + fragsz > PAGE_SIZE) {
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put_page(nc->page);
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goto refill;
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}
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data = page_address(nc->page) + nc->offset;
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nc->offset += fragsz;
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get_page(nc->page);
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}
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put_cpu_var(netdev_alloc_cache);
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skb = data ? build_skb(data, fragsz) : NULL;
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} else {
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skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
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}
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@ -360,28 +382,6 @@ void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
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}
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EXPORT_SYMBOL(skb_add_rx_frag);
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/**
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* dev_alloc_skb - allocate an skbuff for receiving
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* @length: length to allocate
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*
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* Allocate a new &sk_buff and assign it a usage count of one. The
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* buffer has unspecified headroom built in. Users should allocate
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* the headroom they think they need without accounting for the
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* built in space. The built in space is used for optimisations.
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*
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* %NULL is returned if there is no free memory. Although this function
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* allocates memory it can be called from an interrupt.
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*/
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struct sk_buff *dev_alloc_skb(unsigned int length)
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{
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/*
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* There is more code here than it seems:
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* __dev_alloc_skb is an inline
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*/
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return __dev_alloc_skb(length, GFP_ATOMIC);
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}
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EXPORT_SYMBOL(dev_alloc_skb);
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static void skb_drop_list(struct sk_buff **listp)
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{
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struct sk_buff *list = *listp;
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