[thirdparty/linux.git] / net / core / skbuff.c

/*
 *	Routines having to do with the 'struct sk_buff' memory handlers.
 *
 *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
 *			Florian La Roche <rzsfl@rz.uni-sb.de>
 *
 *	Fixes:
 *		Alan Cox	:	Fixed the worst of the load
 *					balancer bugs.
 *		Dave Platt	:	Interrupt stacking fix.
 *	Richard Kooijman	:	Timestamp fixes.
 *		Alan Cox	:	Changed buffer format.
 *		Alan Cox	:	destructor hook for AF_UNIX etc.
 *		Linus Torvalds	:	Better skb_clone.
 *		Alan Cox	:	Added skb_copy.
 *		Alan Cox	:	Added all the changed routines Linus
 *					only put in the headers
 *		Ray VanTassle	:	Fixed --skb->lock in free
 *		Alan Cox	:	skb_copy copy arp field
 *		Andi Kleen	:	slabified it.
 *		Robert Olsson	:	Removed skb_head_pool
 *
 *	NOTE:
 *		The __skb_ routines should be called with interrupts
 *	disabled, or you better be *real* sure that the operation is atomic
 *	with respect to whatever list is being frobbed (e.g. via lock_sock()
 *	or via disabling bottom half handlers, etc).
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

/*
 *	The functions in this file will not compile correctly with gcc 2.4.x
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/kmemcheck.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#ifdef CONFIG_NET_CLS_ACT
#include <net/pkt_sched.h>
#endif
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/splice.h>
#include <linux/cache.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/errqueue.h>
#include <linux/prefetch.h>

#include <net/protocol.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <net/xfrm.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <trace/events/skb.h>

#include "kmap_skb.h"

static struct kmem_cache *skbuff_head_cache __read_mostly;
static struct kmem_cache *skbuff_fclone_cache __read_mostly;

static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
				  struct pipe_buffer *buf)
{
	put_page(buf->page);
}

static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
				struct pipe_buffer *buf)
{
	get_page(buf->page);
}

static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
			       struct pipe_buffer *buf)
{
	return 1;
}


/* Pipe buffer operations for a socket. */
static const struct pipe_buf_operations sock_pipe_buf_ops = {
	.can_merge = 0,
	.map = generic_pipe_buf_map,
	.unmap = generic_pipe_buf_unmap,
	.confirm = generic_pipe_buf_confirm,
	.release = sock_pipe_buf_release,
	.steal = sock_pipe_buf_steal,
	.get = sock_pipe_buf_get,
};

/*
 *	Keep out-of-line to prevent kernel bloat.
 *	__builtin_return_address is not used because it is not always
 *	reliable.
 */

/**
 *	skb_over_panic	- 	private function
 *	@skb: buffer
 *	@sz: size
 *	@here: address
 *
 *	Out of line support code for skb_put(). Not user callable.
 */
static void skb_over_panic(struct sk_buff *skb, int sz, void *here)
{
	printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
			  "data:%p tail:%#lx end:%#lx dev:%s\n",
	       here, skb->len, sz, skb->head, skb->data,
	       (unsigned long)skb->tail, (unsigned long)skb->end,
	       skb->dev ? skb->dev->name : "<NULL>");
	BUG();
}

/**
 *	skb_under_panic	- 	private function
 *	@skb: buffer
 *	@sz: size
 *	@here: address
 *
 *	Out of line support code for skb_push(). Not user callable.
 */

static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
{
	printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
			  "data:%p tail:%#lx end:%#lx dev:%s\n",
	       here, skb->len, sz, skb->head, skb->data,
	       (unsigned long)skb->tail, (unsigned long)skb->end,
	       skb->dev ? skb->dev->name : "<NULL>");
	BUG();
}

/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
 *	'private' fields and also do memory statistics to find all the
 *	[BEEP] leaks.
 *
 */

/**
 *	__alloc_skb	-	allocate a network buffer
 *	@size: size to allocate
 *	@gfp_mask: allocation mask
 *	@fclone: allocate from fclone cache instead of head cache
 *		and allocate a cloned (child) skb
 *	@node: numa node to allocate memory on
 *
 *	Allocate a new &sk_buff. The returned buffer has no headroom and a
 *	tail room of size bytes. The object has a reference count of one.
 *	The return is the buffer. On a failure the return is %NULL.
 *
 *	Buffers may only be allocated from interrupts using a @gfp_mask of
 *	%GFP_ATOMIC.
 */
struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
			    int fclone, int node)
{
	struct kmem_cache *cache;
	struct skb_shared_info *shinfo;
	struct sk_buff *skb;
	u8 *data;

	cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;

	/* Get the HEAD */
	skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
	if (!skb)
		goto out;
	prefetchw(skb);

	/* We do our best to align skb_shared_info on a separate cache
	 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
	 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
	 * Both skb->head and skb_shared_info are cache line aligned.
	 */
	size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
	data = kmalloc_node_track_caller(size, gfp_mask, node);
	if (!data)
		goto nodata;
	/* kmalloc(size) might give us more room than requested.
	 * Put skb_shared_info exactly at the end of allocated zone,
	 * to allow max possible filling before reallocation.
	 */
	size = SKB_WITH_OVERHEAD(ksize(data));
	prefetchw(data + size);

	/*
	 * Only clear those fields we need to clear, not those that we will
	 * actually initialise below. Hence, don't put any more fields after
	 * the tail pointer in struct sk_buff!
	 */
	memset(skb, 0, offsetof(struct sk_buff, tail));
	/* Account for allocated memory : skb + skb->head */
	skb->truesize = SKB_TRUESIZE(size);
	atomic_set(&skb->users, 1);
	skb->head = data;
	skb->data = data;
	skb_reset_tail_pointer(skb);
	skb->end = skb->tail + size;
#ifdef NET_SKBUFF_DATA_USES_OFFSET
	skb->mac_header = ~0U;
#endif

	/* make sure we initialize shinfo sequentially */
	shinfo = skb_shinfo(skb);
	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
	atomic_set(&shinfo->dataref, 1);
	kmemcheck_annotate_variable(shinfo->destructor_arg);

	if (fclone) {
		struct sk_buff *child = skb + 1;
		atomic_t *fclone_ref = (atomic_t *) (child + 1);

		kmemcheck_annotate_bitfield(child, flags1);
		kmemcheck_annotate_bitfield(child, flags2);
		skb->fclone = SKB_FCLONE_ORIG;
		atomic_set(fclone_ref, 1);

		child->fclone = SKB_FCLONE_UNAVAILABLE;
	}
out:
	return skb;
nodata:
	kmem_cache_free(cache, skb);
	skb = NULL;
	goto out;
}
EXPORT_SYMBOL(__alloc_skb);

/**
 *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
 *	@dev: network device to receive on
 *	@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.
 */
struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
		unsigned int length, gfp_t gfp_mask)
{
	struct sk_buff *skb;

	skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
	if (likely(skb)) {
		skb_reserve(skb, NET_SKB_PAD);
		skb->dev = dev;
	}
	return skb;
}
EXPORT_SYMBOL(__netdev_alloc_skb);

void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
		int size)
{
	skb_fill_page_desc(skb, i, page, off, size);
	skb->len += size;
	skb->data_len += size;
	skb->truesize += size;
}
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;

	*listp = NULL;

	do {
		struct sk_buff *this = list;
		list = list->next;
		kfree_skb(this);
	} while (list);
}

static inline void skb_drop_fraglist(struct sk_buff *skb)
{
	skb_drop_list(&skb_shinfo(skb)->frag_list);
}

static void skb_clone_fraglist(struct sk_buff *skb)
{
	struct sk_buff *list;

	skb_walk_frags(skb, list)
		skb_get(list);
}

static void skb_release_data(struct sk_buff *skb)
{
	if (!skb->cloned ||
	    !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
			       &skb_shinfo(skb)->dataref)) {
		if (skb_shinfo(skb)->nr_frags) {
			int i;
			for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
				skb_frag_unref(skb, i);
		}

		/*
		 * If skb buf is from userspace, we need to notify the caller
		 * the lower device DMA has done;
		 */
		if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
			struct ubuf_info *uarg;

			uarg = skb_shinfo(skb)->destructor_arg;
			if (uarg->callback)
				uarg->callback(uarg);
		}

		if (skb_has_frag_list(skb))
			skb_drop_fraglist(skb);

		kfree(skb->head);
	}
}

/*
 *	Free an skbuff by memory without cleaning the state.
 */
static void kfree_skbmem(struct sk_buff *skb)
{
	struct sk_buff *other;
	atomic_t *fclone_ref;

	switch (skb->fclone) {
	case SKB_FCLONE_UNAVAILABLE:
		kmem_cache_free(skbuff_head_cache, skb);
		break;

	case SKB_FCLONE_ORIG:
		fclone_ref = (atomic_t *) (skb + 2);
		if (atomic_dec_and_test(fclone_ref))
			kmem_cache_free(skbuff_fclone_cache, skb);
		break;

	case SKB_FCLONE_CLONE:
		fclone_ref = (atomic_t *) (skb + 1);
		other = skb - 1;

		/* The clone portion is available for
		 * fast-cloning again.
		 */
		skb->fclone = SKB_FCLONE_UNAVAILABLE;

		if (atomic_dec_and_test(fclone_ref))
			kmem_cache_free(skbuff_fclone_cache, other);
		break;
	}
}

static void skb_release_head_state(struct sk_buff *skb)
{
	skb_dst_drop(skb);
#ifdef CONFIG_XFRM
	secpath_put(skb->sp);
#endif
	if (skb->destructor) {
		WARN_ON(in_irq());
		skb->destructor(skb);
	}
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
	nf_conntrack_put(skb->nfct);
#endif
#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
	nf_conntrack_put_reasm(skb->nfct_reasm);
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
	nf_bridge_put(skb->nf_bridge);
#endif
/* XXX: IS this still necessary? - JHS */
#ifdef CONFIG_NET_SCHED
	skb->tc_index = 0;
#ifdef CONFIG_NET_CLS_ACT
	skb->tc_verd = 0;
#endif
#endif
}

/* Free everything but the sk_buff shell. */
static void skb_release_all(struct sk_buff *skb)
{
	skb_release_head_state(skb);
	skb_release_data(skb);
}

/**
 *	__kfree_skb - private function
 *	@skb: buffer
 *
 *	Free an sk_buff. Release anything attached to the buffer.
 *	Clean the state. This is an internal helper function. Users should
 *	always call kfree_skb
 */

void __kfree_skb(struct sk_buff *skb)
{
	skb_release_all(skb);
	kfree_skbmem(skb);
}
EXPORT_SYMBOL(__kfree_skb);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Routines having to do with the 'struct sk_buff' memory handlers.
	3	*
113aa838	4	* Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
1da177e4 LT	5	* Florian La Roche <rzsfl@rz.uni-sb.de>
1da177e4 LT	6	*
1da177e4 LT	7	* Fixes:
	8	* Alan Cox : Fixed the worst of the load
	9	* balancer bugs.
	10	* Dave Platt : Interrupt stacking fix.
	11	* Richard Kooijman : Timestamp fixes.
	12	* Alan Cox : Changed buffer format.
	13	* Alan Cox : destructor hook for AF_UNIX etc.
	14	* Linus Torvalds : Better skb_clone.
	15	* Alan Cox : Added skb_copy.
	16	* Alan Cox : Added all the changed routines Linus
	17	* only put in the headers
	18	* Ray VanTassle : Fixed --skb->lock in free
	19	* Alan Cox : skb_copy copy arp field
	20	* Andi Kleen : slabified it.
	21	* Robert Olsson : Removed skb_head_pool
	22	*
	23	* NOTE:
	24	* The __skb_ routines should be called with interrupts
	25	* disabled, or you better be real sure that the operation is atomic
	26	* with respect to whatever list is being frobbed (e.g. via lock_sock()
	27	* or via disabling bottom half handlers, etc).
	28	*
	29	* This program is free software; you can redistribute it and/or
	30	* modify it under the terms of the GNU General Public License
	31	* as published by the Free Software Foundation; either version
	32	* 2 of the License, or (at your option) any later version.
	33	*/
	34
	35	/*
	36	* The functions in this file will not compile correctly with gcc 2.4.x
	37	*/
	38
1da177e4 LT	39	#include <linux/module.h>
	40	#include <linux/types.h>
	41	#include <linux/kernel.h>
fe55f6d5	42	#include <linux/kmemcheck.h>
1da177e4 LT	43	#include <linux/mm.h>
	44	#include <linux/interrupt.h>
	45	#include <linux/in.h>
	46	#include <linux/inet.h>
	47	#include <linux/slab.h>
	48	#include <linux/netdevice.h>
	49	#ifdef CONFIG_NET_CLS_ACT
	50	#include <net/pkt_sched.h>
	51	#endif
	52	#include <linux/string.h>
	53	#include <linux/skbuff.h>
9c55e01c	54	#include <linux/splice.h>
1da177e4 LT	55	#include <linux/cache.h>
	56	#include <linux/rtnetlink.h>
	57	#include <linux/init.h>
716ea3a7	58	#include <linux/scatterlist.h>
ac45f602	59	#include <linux/errqueue.h>
268bb0ce	60	#include <linux/prefetch.h>
1da177e4 LT	61
	62	#include <net/protocol.h>
	63	#include <net/dst.h>
	64	#include <net/sock.h>
	65	#include <net/checksum.h>
	66	#include <net/xfrm.h>
	67
	68	#include <asm/uaccess.h>
	69	#include <asm/system.h>
ad8d75ff	70	#include <trace/events/skb.h>
1da177e4	71
a1f8e7f7 AV	72	#include "kmap_skb.h"
a1f8e7f7 AV	73
e18b890b CL	74	static struct kmem_cache *skbuff_head_cache __read_mostly;
e18b890b CL	75	static struct kmem_cache *skbuff_fclone_cache __read_mostly;
1da177e4	76
9c55e01c JA	77	static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
	78	struct pipe_buffer *buf)
	79	{
8b9d3728	80	put_page(buf->page);
9c55e01c JA	81	}
	82
	83	static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
	84	struct pipe_buffer *buf)
	85	{
8b9d3728	86	get_page(buf->page);
9c55e01c JA	87	}
	88
	89	static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
	90	struct pipe_buffer *buf)
	91	{
	92	return 1;
	93	}
	94
	95
	96	/* Pipe buffer operations for a socket. */
28dfef8f	97	static const struct pipe_buf_operations sock_pipe_buf_ops = {
9c55e01c JA	98	.can_merge = 0,
	99	.map = generic_pipe_buf_map,
	100	.unmap = generic_pipe_buf_unmap,
	101	.confirm = generic_pipe_buf_confirm,
	102	.release = sock_pipe_buf_release,
	103	.steal = sock_pipe_buf_steal,
	104	.get = sock_pipe_buf_get,
	105	};
	106
1da177e4 LT	107	/*
	108	* Keep out-of-line to prevent kernel bloat.
	109	* __builtin_return_address is not used because it is not always
	110	* reliable.
	111	*/
	112
	113	/**
	114	* skb_over_panic - private function
	115	* @skb: buffer
	116	* @sz: size
	117	* @here: address
	118	*
	119	* Out of line support code for skb_put(). Not user callable.
	120	*/
ccb7c773	121	static void skb_over_panic(struct sk_buff skb, int sz, void here)
1da177e4	122	{
26095455	123	printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
4305b541	124	"data:%p tail:%#lx end:%#lx dev:%s\n",
27a884dc	125	here, skb->len, sz, skb->head, skb->data,
4305b541	126	(unsigned long)skb->tail, (unsigned long)skb->end,
26095455	127	skb->dev ? skb->dev->name : "<NULL>");
1da177e4 LT	128	BUG();
	129	}
	130
	131	/**
	132	* skb_under_panic - private function
	133	* @skb: buffer
	134	* @sz: size
	135	* @here: address
	136	*
	137	* Out of line support code for skb_push(). Not user callable.
	138	*/
	139
ccb7c773	140	static void skb_under_panic(struct sk_buff skb, int sz, void here)
1da177e4	141	{
26095455	142	printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
4305b541	143	"data:%p tail:%#lx end:%#lx dev:%s\n",
27a884dc	144	here, skb->len, sz, skb->head, skb->data,
4305b541	145	(unsigned long)skb->tail, (unsigned long)skb->end,
26095455	146	skb->dev ? skb->dev->name : "<NULL>");
1da177e4 LT	147	BUG();
	148	}
	149
	150	/* Allocate a new skbuff. We do this ourselves so we can fill in a few
	151	* 'private' fields and also do memory statistics to find all the
	152	* [BEEP] leaks.
	153	*
	154	*/
	155
	156	/**
d179cd12	157	* __alloc_skb - allocate a network buffer
1da177e4 LT	158	* @size: size to allocate
1da177e4 LT	159	* @gfp_mask: allocation mask
c83c2486 RD	160	* @fclone: allocate from fclone cache instead of head cache
c83c2486 RD	161	* and allocate a cloned (child) skb
b30973f8	162	* @node: numa node to allocate memory on
1da177e4 LT	163	*
	164	* Allocate a new &sk_buff. The returned buffer has no headroom and a
	165	* tail room of size bytes. The object has a reference count of one.
	166	* The return is the buffer. On a failure the return is %NULL.
	167	*
	168	* Buffers may only be allocated from interrupts using a @gfp_mask of
	169	* %GFP_ATOMIC.
	170	*/
dd0fc66f	171	struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
b30973f8	172	int fclone, int node)
1da177e4	173	{
e18b890b	174	struct kmem_cache *cache;
4947d3ef	175	struct skb_shared_info *shinfo;
1da177e4 LT	176	struct sk_buff *skb;
	177	u8 *data;
	178
8798b3fb HX	179	cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
8798b3fb HX	180
1da177e4	181	/* Get the HEAD */
b30973f8	182	skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
1da177e4 LT	183	if (!skb)
1da177e4 LT	184	goto out;
ec7d2f2c	185	prefetchw(skb);
1da177e4	186
87fb4b7b ED	187	/* We do our best to align skb_shared_info on a separate cache
	188	* line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
	189	* aligned memory blocks, unless SLUB/SLAB debug is enabled.
	190	* Both skb->head and skb_shared_info are cache line aligned.
	191	*/
	192	size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
	193	data = kmalloc_node_track_caller(size, gfp_mask, node);
1da177e4 LT	194	if (!data)
1da177e4 LT	195	goto nodata;
87fb4b7b ED	196	/* kmalloc(size) might give us more room than requested.
	197	* Put skb_shared_info exactly at the end of allocated zone,
	198	* to allow max possible filling before reallocation.
	199	*/
	200	size = SKB_WITH_OVERHEAD(ksize(data));
ec7d2f2c	201	prefetchw(data + size);
1da177e4	202
ca0605a7	203	/*
c8005785 JB	204	* Only clear those fields we need to clear, not those that we will
	205	* actually initialise below. Hence, don't put any more fields after
	206	* the tail pointer in struct sk_buff!
ca0605a7 ACM	207	*/
ca0605a7 ACM	208	memset(skb, 0, offsetof(struct sk_buff, tail));
87fb4b7b ED	209	/* Account for allocated memory : skb + skb->head */
87fb4b7b ED	210	skb->truesize = SKB_TRUESIZE(size);
1da177e4 LT	211	atomic_set(&skb->users, 1);
	212	skb->head = data;
	213	skb->data = data;
27a884dc	214	skb_reset_tail_pointer(skb);
4305b541	215	skb->end = skb->tail + size;
19633e12 SH	216	#ifdef NET_SKBUFF_DATA_USES_OFFSET
	217	skb->mac_header = ~0U;
	218	#endif
	219
4947d3ef BL	220	/* make sure we initialize shinfo sequentially */
4947d3ef BL	221	shinfo = skb_shinfo(skb);
ec7d2f2c	222	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
4947d3ef	223	atomic_set(&shinfo->dataref, 1);
c2aa3665	224	kmemcheck_annotate_variable(shinfo->destructor_arg);
4947d3ef	225
d179cd12 DM	226	if (fclone) {
	227	struct sk_buff *child = skb + 1;
	228	atomic_t fclone_ref = (atomic_t ) (child + 1);
1da177e4	229
fe55f6d5 VN	230	kmemcheck_annotate_bitfield(child, flags1);
fe55f6d5 VN	231	kmemcheck_annotate_bitfield(child, flags2);
d179cd12 DM	232	skb->fclone = SKB_FCLONE_ORIG;
	233	atomic_set(fclone_ref, 1);
	234
	235	child->fclone = SKB_FCLONE_UNAVAILABLE;
	236	}
1da177e4 LT	237	out:
	238	return skb;
	239	nodata:
8798b3fb	240	kmem_cache_free(cache, skb);
1da177e4 LT	241	skb = NULL;
1da177e4 LT	242	goto out;
1da177e4	243	}
b4ac530f	244	EXPORT_SYMBOL(__alloc_skb);
1da177e4	245
8af27456 CH	246	/**
	247	* __netdev_alloc_skb - allocate an skbuff for rx on a specific device
	248	* @dev: network device to receive on
	249	* @length: length to allocate
	250	* @gfp_mask: get_free_pages mask, passed to alloc_skb
	251	*
	252	* Allocate a new &sk_buff and assign it a usage count of one. The
	253	* buffer has unspecified headroom built in. Users should allocate
	254	* the headroom they think they need without accounting for the
	255	* built in space. The built in space is used for optimisations.
	256	*
	257	* %NULL is returned if there is no free memory.
	258	*/
	259	struct sk_buff __netdev_alloc_skb(struct net_device dev,
	260	unsigned int length, gfp_t gfp_mask)
	261	{
	262	struct sk_buff *skb;
	263
564824b0	264	skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
7b2e497a	265	if (likely(skb)) {
8af27456	266	skb_reserve(skb, NET_SKB_PAD);
7b2e497a CH	267	skb->dev = dev;
7b2e497a CH	268	}
8af27456 CH	269	return skb;
8af27456 CH	270	}
b4ac530f	271	EXPORT_SYMBOL(__netdev_alloc_skb);
1da177e4	272
654bed16 PZ	273	void skb_add_rx_frag(struct sk_buff skb, int i, struct page page, int off,
	274	int size)
	275	{
	276	skb_fill_page_desc(skb, i, page, off, size);
	277	skb->len += size;
	278	skb->data_len += size;
	279	skb->truesize += size;
	280	}
	281	EXPORT_SYMBOL(skb_add_rx_frag);
	282
f58518e6 IJ	283	/**
	284	* dev_alloc_skb - allocate an skbuff for receiving
	285	* @length: length to allocate
	286	*
	287	* Allocate a new &sk_buff and assign it a usage count of one. The
	288	* buffer has unspecified headroom built in. Users should allocate
	289	* the headroom they think they need without accounting for the
	290	* built in space. The built in space is used for optimisations.
	291	*
	292	* %NULL is returned if there is no free memory. Although this function
	293	* allocates memory it can be called from an interrupt.
	294	*/
	295	struct sk_buff *dev_alloc_skb(unsigned int length)
	296	{
1483b874 DV	297	/*
1483b874 DV	298	* There is more code here than it seems:
a0f55e0e	299	* __dev_alloc_skb is an inline
1483b874	300	*/
f58518e6 IJ	301	return __dev_alloc_skb(length, GFP_ATOMIC);
	302	}
	303	EXPORT_SYMBOL(dev_alloc_skb);
	304
27b437c8	305	static void skb_drop_list(struct sk_buff **listp)
1da177e4	306	{
27b437c8	307	struct sk_buff list = listp;
1da177e4	308
27b437c8	309	*listp = NULL;
1da177e4 LT	310
	311	do {
	312	struct sk_buff *this = list;
	313	list = list->next;
	314	kfree_skb(this);
	315	} while (list);
	316	}
	317
27b437c8 HX	318	static inline void skb_drop_fraglist(struct sk_buff *skb)
	319	{
	320	skb_drop_list(&skb_shinfo(skb)->frag_list);
	321	}
	322
1da177e4 LT	323	static void skb_clone_fraglist(struct sk_buff *skb)
	324	{
	325	struct sk_buff *list;
	326
fbb398a8	327	skb_walk_frags(skb, list)
1da177e4 LT	328	skb_get(list);
	329	}
	330
5bba1712	331	static void skb_release_data(struct sk_buff *skb)
1da177e4 LT	332	{
	333	if (!skb->cloned \|\|
	334	!atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
	335	&skb_shinfo(skb)->dataref)) {
	336	if (skb_shinfo(skb)->nr_frags) {
	337	int i;
	338	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
ea2ab693	339	skb_frag_unref(skb, i);
1da177e4 LT	340	}
1da177e4 LT	341
a6686f2f SM	342	/*
	343	* If skb buf is from userspace, we need to notify the caller
	344	* the lower device DMA has done;
	345	*/
	346	if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
	347	struct ubuf_info *uarg;
	348
	349	uarg = skb_shinfo(skb)->destructor_arg;
	350	if (uarg->callback)
	351	uarg->callback(uarg);
	352	}
	353
21dc3301	354	if (skb_has_frag_list(skb))
1da177e4 LT	355	skb_drop_fraglist(skb);
	356
	357	kfree(skb->head);
	358	}
	359	}
	360
	361	/*
	362	* Free an skbuff by memory without cleaning the state.
	363	*/
2d4baff8	364	static void kfree_skbmem(struct sk_buff *skb)
1da177e4	365	{
d179cd12 DM	366	struct sk_buff *other;
	367	atomic_t *fclone_ref;
	368
d179cd12 DM	369	switch (skb->fclone) {
	370	case SKB_FCLONE_UNAVAILABLE:
	371	kmem_cache_free(skbuff_head_cache, skb);
	372	break;
	373
	374	case SKB_FCLONE_ORIG:
	375	fclone_ref = (atomic_t *) (skb + 2);
	376	if (atomic_dec_and_test(fclone_ref))
	377	kmem_cache_free(skbuff_fclone_cache, skb);
	378	break;
	379
	380	case SKB_FCLONE_CLONE:
	381	fclone_ref = (atomic_t *) (skb + 1);
	382	other = skb - 1;
	383
	384	/* The clone portion is available for
	385	* fast-cloning again.
	386	*/
	387	skb->fclone = SKB_FCLONE_UNAVAILABLE;
	388
	389	if (atomic_dec_and_test(fclone_ref))
	390	kmem_cache_free(skbuff_fclone_cache, other);
	391	break;
3ff50b79	392	}
1da177e4 LT	393	}
1da177e4 LT	394
04a4bb55	395	static void skb_release_head_state(struct sk_buff *skb)
1da177e4	396	{
adf30907	397	skb_dst_drop(skb);
1da177e4 LT	398	#ifdef CONFIG_XFRM
	399	secpath_put(skb->sp);
	400	#endif
9c2b3328 SH	401	if (skb->destructor) {
9c2b3328 SH	402	WARN_ON(in_irq());
1da177e4 LT	403	skb->destructor(skb);
1da177e4 LT	404	}
9fb9cbb1	405	#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
5f79e0f9	406	nf_conntrack_put(skb->nfct);
2fc72c7b KK	407	#endif
2fc72c7b KK	408	#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
9fb9cbb1 YK	409	nf_conntrack_put_reasm(skb->nfct_reasm);
9fb9cbb1 YK	410	#endif
1da177e4 LT	411	#ifdef CONFIG_BRIDGE_NETFILTER
	412	nf_bridge_put(skb->nf_bridge);
	413	#endif
1da177e4 LT	414	/* XXX: IS this still necessary? - JHS */
	415	#ifdef CONFIG_NET_SCHED
	416	skb->tc_index = 0;
	417	#ifdef CONFIG_NET_CLS_ACT
	418	skb->tc_verd = 0;
1da177e4 LT	419	#endif
1da177e4 LT	420	#endif
04a4bb55 LB	421	}
	422
	423	/* Free everything but the sk_buff shell. */
	424	static void skb_release_all(struct sk_buff *skb)
	425	{
	426	skb_release_head_state(skb);
2d4baff8 HX	427	skb_release_data(skb);
	428	}
	429
	430	/**
	431	* __kfree_skb - private function
	432	* @skb: buffer
	433	*
	434	* Free an sk_buff. Release anything attached to the buffer.
	435	* Clean the state. This is an internal helper function. Users should
	436	* always call kfree_skb
	437	*/
1da177e4	438
2d4baff8 HX	439	void __kfree_skb(struct sk_buff *skb)
	440	{
	441	skb_release_all(skb);
1da177e4 LT	442	kfree_skbmem(skb);
1da177e4 LT	443	}
b4ac530f	444	EXPORT_SYMBOL(__kfree_skb);
1da177e4	445