Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1460 insertions, 0 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
new file mode 100644
index 0000000..bf02ca9
--- /dev/null
+++ b/net/core/skbuff.c
@@ -0,0 +1,1460 @@
+/*
+ *	Routines having to do with the 'struct sk_buff' memory handlers.
+ *
+ *	Authors:	Alan Cox <iiitac@pyr.swan.ac.uk>
+ *			Florian La Roche <rzsfl@rz.uni-sb.de>
+ *
+ *	Version:	$Id: skbuff.c,v 1.90 2001/11/07 05:56:19 davem Exp $
+ *
+ *	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/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.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/cache.h>
+#include <linux/rtnetlink.h>
+#include <linux/init.h>
+#include <linux/highmem.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>
+
+static kmem_cache_t *skbuff_head_cache;
+
+/*
+ *	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.
+ */
+void skb_over_panic(struct sk_buff *skb, int sz, void *here)
+{
+	printk(KERN_INFO "skput:over: %p:%d put:%d dev:%s",
+		here, skb->len, sz, 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.
+ */
+
+void skb_under_panic(struct sk_buff *skb, int sz, void *here)
+{
+	printk(KERN_INFO "skput:under: %p:%d put:%d dev:%s",
+               here, skb->len, sz, 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
+ *
+ *	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, int gfp_mask)
+{
+	struct sk_buff *skb;
+	u8 *data;
+
+	/* Get the HEAD */
+	skb = kmem_cache_alloc(skbuff_head_cache,
+			       gfp_mask & ~__GFP_DMA);
+	if (!skb)
+		goto out;
+
+	/* Get the DATA. Size must match skb_add_mtu(). */
+	size = SKB_DATA_ALIGN(size);
+	data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
+	if (!data)
+		goto nodata;
+
+	memset(skb, 0, offsetof(struct sk_buff, truesize));
+	skb->truesize = size + sizeof(struct sk_buff);
+	atomic_set(&skb->users, 1);
+	skb->head = data;
+	skb->data = data;
+	skb->tail = data;
+	skb->end  = data + size;
+
+	atomic_set(&(skb_shinfo(skb)->dataref), 1);
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb_shinfo(skb)->tso_size = 0;
+	skb_shinfo(skb)->tso_segs = 0;
+	skb_shinfo(skb)->frag_list = NULL;
+out:
+	return skb;
+nodata:
+	kmem_cache_free(skbuff_head_cache, skb);
+	skb = NULL;
+	goto out;
+}
+
+/**
+ *	alloc_skb_from_cache	-	allocate a network buffer
+ *	@cp: kmem_cache from which to allocate the data area
+ *           (object size must be big enough for @size bytes + skb overheads)
+ *	@size: size to allocate
+ *	@gfp_mask: allocation mask
+ *
+ *	Allocate a new &sk_buff. The returned buffer has no headroom and
+ *	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_from_cache(kmem_cache_t *cp,
+				     unsigned int size, int gfp_mask)
+{
+	struct sk_buff *skb;
+	u8 *data;
+
+	/* Get the HEAD */
+	skb = kmem_cache_alloc(skbuff_head_cache,
+			       gfp_mask & ~__GFP_DMA);
+	if (!skb)
+		goto out;
+
+	/* Get the DATA. */
+	size = SKB_DATA_ALIGN(size);
+	data = kmem_cache_alloc(cp, gfp_mask);
+	if (!data)
+		goto nodata;
+
+	memset(skb, 0, offsetof(struct sk_buff, truesize));
+	skb->truesize = size + sizeof(struct sk_buff);
+	atomic_set(&skb->users, 1);
+	skb->head = data;
+	skb->data = data;
+	skb->tail = data;
+	skb->end  = data + size;
+
+	atomic_set(&(skb_shinfo(skb)->dataref), 1);
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb_shinfo(skb)->tso_size = 0;
+	skb_shinfo(skb)->tso_segs = 0;
+	skb_shinfo(skb)->frag_list = NULL;
+out:
+	return skb;
+nodata:
+	kmem_cache_free(skbuff_head_cache, skb);
+	skb = NULL;
+	goto out;
+}
+
+
+static void skb_drop_fraglist(struct sk_buff *skb)
+{
+	struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+	skb_shinfo(skb)->frag_list = NULL;
+
+	do {
+		struct sk_buff *this = list;
+		list = list->next;
+		kfree_skb(this);
+	} while (list);
+}
+
+static void skb_clone_fraglist(struct sk_buff *skb)
+{
+	struct sk_buff *list;
+
+	for (list = skb_shinfo(skb)->frag_list; list; list = list->next)
+		skb_get(list);
+}
+
+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++)
+				put_page(skb_shinfo(skb)->frags[i].page);
+		}
+
+		if (skb_shinfo(skb)->frag_list)
+			skb_drop_fraglist(skb);
+
+		kfree(skb->head);
+	}
+}
+
+/*
+ *	Free an skbuff by memory without cleaning the state.
+ */
+void kfree_skbmem(struct sk_buff *skb)
+{
+	skb_release_data(skb);
+	kmem_cache_free(skbuff_head_cache, 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)
+{
+	if (skb->list) {
+	 	printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
+		       "on a list (from %p).\n", NET_CALLER(skb));
+		BUG();
+	}
+
+	dst_release(skb->dst);
+#ifdef CONFIG_XFRM
+	secpath_put(skb->sp);
+#endif
+	if(skb->destructor) {
+		if (in_irq())
+			printk(KERN_WARNING "Warning: kfree_skb on "
+					    "hard IRQ %p\n", NET_CALLER(skb));
+		skb->destructor(skb);
+	}
+#ifdef CONFIG_NETFILTER
+	nf_conntrack_put(skb->nfct);
+#ifdef CONFIG_BRIDGE_NETFILTER
+	nf_bridge_put(skb->nf_bridge);
+#endif
+#endif
+/* XXX: IS this still necessary? - JHS */
+#ifdef CONFIG_NET_SCHED
+	skb->tc_index = 0;
+#ifdef CONFIG_NET_CLS_ACT
+	skb->tc_verd = 0;
+	skb->tc_classid = 0;
+#endif
+#endif
+
+	kfree_skbmem(skb);
+}
+
+/**
+ *	skb_clone	-	duplicate an sk_buff
+ *	@skb: buffer to clone
+ *	@gfp_mask: allocation priority
+ *
+ *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
+ *	copies share the same packet data but not structure. The new
+ *	buffer has a reference count of 1. If the allocation fails the
+ *	function returns %NULL otherwise the new buffer is returned.
+ *
+ *	If this function is called from an interrupt gfp_mask() must be
+ *	%GFP_ATOMIC.
+ */
+
+struct sk_buff *skb_clone(struct sk_buff *skb, int gfp_mask)
+{
+	struct sk_buff *n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
+
+	if (!n) 
+		return NULL;
+
+#define C(x) n->x = skb->x
+
+	n->next = n->prev = NULL;
+	n->list = NULL;
+	n->sk = NULL;
+	C(stamp);
+	C(dev);
+	C(real_dev);
+	C(h);
+	C(nh);
+	C(mac);
+	C(dst);
+	dst_clone(skb->dst);
+	C(sp);
+#ifdef CONFIG_INET
+	secpath_get(skb->sp);
+#endif
+	memcpy(n->cb, skb->cb, sizeof(skb->cb));
+	C(len);
+	C(data_len);
+	C(csum);
+	C(local_df);
+	n->cloned = 1;
+	n->nohdr = 0;
+	C(pkt_type);
+	C(ip_summed);
+	C(priority);
+	C(protocol);
+	C(security);
+	n->destructor = NULL;
+#ifdef CONFIG_NETFILTER
+	C(nfmark);
+	C(nfcache);
+	C(nfct);
+	nf_conntrack_get(skb->nfct);
+	C(nfctinfo);
+#ifdef CONFIG_NETFILTER_DEBUG
+	C(nf_debug);
+#endif
+#ifdef CONFIG_BRIDGE_NETFILTER
+	C(nf_bridge);
+	nf_bridge_get(skb->nf_bridge);
+#endif
+#endif /*CONFIG_NETFILTER*/
+#if defined(CONFIG_HIPPI)
+	C(private);
+#endif
+#ifdef CONFIG_NET_SCHED
+	C(tc_index);
+#ifdef CONFIG_NET_CLS_ACT
+	n->tc_verd = SET_TC_VERD(skb->tc_verd,0);
+	n->tc_verd = CLR_TC_OK2MUNGE(skb->tc_verd);
+	n->tc_verd = CLR_TC_MUNGED(skb->tc_verd);
+	C(input_dev);
+	C(tc_classid);
+#endif
+
+#endif
+	C(truesize);
+	atomic_set(&n->users, 1);
+	C(head);
+	C(data);
+	C(tail);
+	C(end);
+
+	atomic_inc(&(skb_shinfo(skb)->dataref));
+	skb->cloned = 1;
+
+	return n;
+}
+
+static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+{
+	/*
+	 *	Shift between the two data areas in bytes
+	 */
+	unsigned long offset = new->data - old->data;
+
+	new->list	= NULL;
+	new->sk		= NULL;
+	new->dev	= old->dev;
+	new->real_dev	= old->real_dev;
+	new->priority	= old->priority;
+	new->protocol	= old->protocol;
+	new->dst	= dst_clone(old->dst);
+#ifdef CONFIG_INET
+	new->sp		= secpath_get(old->sp);
+#endif
+	new->h.raw	= old->h.raw + offset;
+	new->nh.raw	= old->nh.raw + offset;
+	new->mac.raw	= old->mac.raw + offset;
+	memcpy(new->cb, old->cb, sizeof(old->cb));
+	new->local_df	= old->local_df;
+	new->pkt_type	= old->pkt_type;
+	new->stamp	= old->stamp;
+	new->destructor = NULL;
+	new->security	= old->security;
+#ifdef CONFIG_NETFILTER
+	new->nfmark	= old->nfmark;
+	new->nfcache	= old->nfcache;
+	new->nfct	= old->nfct;
+	nf_conntrack_get(old->nfct);
+	new->nfctinfo	= old->nfctinfo;
+#ifdef CONFIG_NETFILTER_DEBUG
+	new->nf_debug	= old->nf_debug;
+#endif
+#ifdef CONFIG_BRIDGE_NETFILTER
+	new->nf_bridge	= old->nf_bridge;
+	nf_bridge_get(old->nf_bridge);
+#endif
+#endif
+#ifdef CONFIG_NET_SCHED
+#ifdef CONFIG_NET_CLS_ACT
+	new->tc_verd = old->tc_verd;
+#endif
+	new->tc_index	= old->tc_index;
+#endif
+	atomic_set(&new->users, 1);
+	skb_shinfo(new)->tso_size = skb_shinfo(old)->tso_size;
+	skb_shinfo(new)->tso_segs = skb_shinfo(old)->tso_segs;
+}
+
+/**
+ *	skb_copy	-	create private copy of an sk_buff
+ *	@skb: buffer to copy
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and its data. This is used when the
+ *	caller wishes to modify the data and needs a private copy of the
+ *	data to alter. Returns %NULL on failure or the pointer to the buffer
+ *	on success. The returned buffer has a reference count of 1.
+ *
+ *	As by-product this function converts non-linear &sk_buff to linear
+ *	one, so that &sk_buff becomes completely private and caller is allowed
+ *	to modify all the data of returned buffer. This means that this
+ *	function is not recommended for use in circumstances when only
+ *	header is going to be modified. Use pskb_copy() instead.
+ */
+
+struct sk_buff *skb_copy(const struct sk_buff *skb, int gfp_mask)
+{
+	int headerlen = skb->data - skb->head;
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len,
+				      gfp_mask);
+	if (!n)
+		return NULL;
+
+	/* Set the data pointer */
+	skb_reserve(n, headerlen);
+	/* Set the tail pointer and length */
+	skb_put(n, skb->len);
+	n->csum	     = skb->csum;
+	n->ip_summed = skb->ip_summed;
+
+	if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
+		BUG();
+
+	copy_skb_header(n, skb);
+	return n;
+}
+
+
+/**
+ *	pskb_copy	-	create copy of an sk_buff with private head.
+ *	@skb: buffer to copy
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and part of its data, located
+ *	in header. Fragmented data remain shared. This is used when
+ *	the caller wishes to modify only header of &sk_buff and needs
+ *	private copy of the header to alter. Returns %NULL on failure
+ *	or the pointer to the buffer on success.
+ *	The returned buffer has a reference count of 1.
+ */
+
+struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask)
+{
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask);
+
+	if (!n)
+		goto out;
+
+	/* Set the data pointer */
+	skb_reserve(n, skb->data - skb->head);
+	/* Set the tail pointer and length */
+	skb_put(n, skb_headlen(skb));
+	/* Copy the bytes */
+	memcpy(n->data, skb->data, n->len);
+	n->csum	     = skb->csum;
+	n->ip_summed = skb->ip_summed;
+
+	n->data_len  = skb->data_len;
+	n->len	     = skb->len;
+
+	if (skb_shinfo(skb)->nr_frags) {
+		int i;
+
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
+			get_page(skb_shinfo(n)->frags[i].page);
+		}
+		skb_shinfo(n)->nr_frags = i;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
+		skb_clone_fraglist(n);
+	}
+
+	copy_skb_header(n, skb);
+out:
+	return n;
+}
+
+/**
+ *	pskb_expand_head - reallocate header of &sk_buff
+ *	@skb: buffer to reallocate
+ *	@nhead: room to add at head
+ *	@ntail: room to add at tail
+ *	@gfp_mask: allocation priority
+ *
+ *	Expands (or creates identical copy, if &nhead and &ntail are zero)
+ *	header of skb. &sk_buff itself is not changed. &sk_buff MUST have
+ *	reference count of 1. Returns zero in the case of success or error,
+ *	if expansion failed. In the last case, &sk_buff is not changed.
+ *
+ *	All the pointers pointing into skb header may change and must be
+ *	reloaded after call to this function.
+ */
+
+int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, int gfp_mask)
+{
+	int i;
+	u8 *data;
+	int size = nhead + (skb->end - skb->head) + ntail;
+	long off;
+
+	if (skb_shared(skb))
+		BUG();
+
+	size = SKB_DATA_ALIGN(size);
+
+	data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
+	if (!data)
+		goto nodata;
+
+	/* Copy only real data... and, alas, header. This should be
+	 * optimized for the cases when header is void. */
+	memcpy(data + nhead, skb->head, skb->tail - skb->head);
+	memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+		get_page(skb_shinfo(skb)->frags[i].page);
+
+	if (skb_shinfo(skb)->frag_list)
+		skb_clone_fraglist(skb);
+
+	skb_release_data(skb);
+
+	off = (data + nhead) - skb->head;
+
+	skb->head     = data;
+	skb->end      = data + size;
+	skb->data    += off;
+	skb->tail    += off;
+	skb->mac.raw += off;
+	skb->h.raw   += off;
+	skb->nh.raw  += off;
+	skb->cloned   = 0;
+	skb->nohdr    = 0;
+	atomic_set(&skb_shinfo(skb)->dataref, 1);
+	return 0;
+
+nodata:
+	return -ENOMEM;
+}
+
+/* Make private copy of skb with writable head and some headroom */
+
+struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
+{
+	struct sk_buff *skb2;
+	int delta = headroom - skb_headroom(skb);
+
+	if (delta <= 0)
+		skb2 = pskb_copy(skb, GFP_ATOMIC);
+	else {
+		skb2 = skb_clone(skb, GFP_ATOMIC);
+		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
+					     GFP_ATOMIC)) {
+			kfree_skb(skb2);
+			skb2 = NULL;
+		}
+	}
+	return skb2;
+}
+
+
+/**
+ *	skb_copy_expand	-	copy and expand sk_buff
+ *	@skb: buffer to copy
+ *	@newheadroom: new free bytes at head
+ *	@newtailroom: new free bytes at tail
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and its data and while doing so
+ *	allocate additional space.
+ *
+ *	This is used when the caller wishes to modify the data and needs a
+ *	private copy of the data to alter as well as more space for new fields.
+ *	Returns %NULL on failure or the pointer to the buffer
+ *	on success. The returned buffer has a reference count of 1.
+ *
+ *	You must pass %GFP_ATOMIC as the allocation priority if this function
+ *	is called from an interrupt.
+ *
+ *	BUG ALERT: ip_summed is not copied. Why does this work? Is it used
+ *	only by netfilter in the cases when checksum is recalculated? --ANK
+ */
+struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
+				int newheadroom, int newtailroom, int gfp_mask)
+{
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
+				      gfp_mask);
+	int head_copy_len, head_copy_off;
+
+	if (!n)
+		return NULL;
+
+	skb_reserve(n, newheadroom);
+
+	/* Set the tail pointer and length */
+	skb_put(n, skb->len);
+
+	head_copy_len = skb_headroom(skb);
+	head_copy_off = 0;
+	if (newheadroom <= head_copy_len)
+		head_copy_len = newheadroom;
+	else
+		head_copy_off = newheadroom - head_copy_len;
+
+	/* Copy the linear header and data. */
+	if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
+			  skb->len + head_copy_len))
+		BUG();
+
+	copy_skb_header(n, skb);
+
+	return n;
+}
+
+/**
+ *	skb_pad			-	zero pad the tail of an skb
+ *	@skb: buffer to pad
+ *	@pad: space to pad
+ *
+ *	Ensure that a buffer is followed by a padding area that is zero
+ *	filled. Used by network drivers which may DMA or transfer data
+ *	beyond the buffer end onto the wire.
+ *
+ *	May return NULL in out of memory cases.
+ */
+ 
+struct sk_buff *skb_pad(struct sk_buff *skb, int pad)
+{
+	struct sk_buff *nskb;
+	
+	/* If the skbuff is non linear tailroom is always zero.. */
+	if (skb_tailroom(skb) >= pad) {
+		memset(skb->data+skb->len, 0, pad);
+		return skb;
+	}
+	
+	nskb = skb_copy_expand(skb, skb_headroom(skb), skb_tailroom(skb) + pad, GFP_ATOMIC);
+	kfree_skb(skb);
+	if (nskb)
+		memset(nskb->data+nskb->len, 0, pad);
+	return nskb;
+}	
+ 
+/* Trims skb to length len. It can change skb pointers, if "realloc" is 1.
+ * If realloc==0 and trimming is impossible without change of data,
+ * it is BUG().
+ */
+
+int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc)
+{
+	int offset = skb_headlen(skb);
+	int nfrags = skb_shinfo(skb)->nr_frags;
+	int i;
+
+	for (i = 0; i < nfrags; i++) {
+		int end = offset + skb_shinfo(skb)->frags[i].size;
+		if (end > len) {
+			if (skb_cloned(skb)) {
+				if (!realloc)
+					BUG();
+				if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+					return -ENOMEM;
+			}
+			if (len <= offset) {
+				put_page(skb_shinfo(skb)->frags[i].page);
+				skb_shinfo(skb)->nr_frags--;
+			} else {
+				skb_shinfo(skb)->frags[i].size = len - offset;
+			}
+		}
+		offset = end;
+	}
+
+	if (offset < len) {
+		skb->data_len -= skb->len - len;
+		skb->len       = len;
+	} else {
+		if (len <= skb_headlen(skb)) {
+			skb->len      = len;
+			skb->data_len = 0;
+			skb->tail     = skb->data + len;
+			if (skb_shinfo(skb)->frag_list && !skb_cloned(skb))
+				skb_drop_fraglist(skb);
+		} else {
+			skb->data_len -= skb->len - len;
+			skb->len       = len;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ *	__pskb_pull_tail - advance tail of skb header
+ *	@skb: buffer to reallocate
+ *	@delta: number of bytes to advance tail
+ *
+ *	The function makes a sense only on a fragmented &sk_buff,
+ *	it expands header moving its tail forward and copying necessary
+ *	data from fragmented part.
+ *
+ *	&sk_buff MUST have reference count of 1.
+ *
+ *	Returns %NULL (and &sk_buff does not change) if pull failed
+ *	or value of new tail of skb in the case of success.
+ *
+ *	All the pointers pointing into skb header may change and must be
+ *	reloaded after call to this function.
+ */
+
+/* Moves tail of skb head forward, copying data from fragmented part,
+ * when it is necessary.
+ * 1. It may fail due to malloc failure.
+ * 2. It may change skb pointers.
+ *
+ * It is pretty complicated. Luckily, it is called only in exceptional cases.
+ */
+unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
+{
+	/* If skb has not enough free space at tail, get new one
+	 * plus 128 bytes for future expansions. If we have enough
+	 * room at tail, reallocate without expansion only if skb is cloned.
+	 */
+	int i, k, eat = (skb->tail + delta) - skb->end;
+
+	if (eat > 0 || skb_cloned(skb)) {
+		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
+				     GFP_ATOMIC))
+			return NULL;
+	}
+
+	if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
+		BUG();
+
+	/* Optimization: no fragments, no reasons to preestimate
+	 * size of pulled pages. Superb.
+	 */
+	if (!skb_shinfo(skb)->frag_list)
+		goto pull_pages;
+
+	/* Estimate size of pulled pages. */
+	eat = delta;
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		if (skb_shinfo(skb)->frags[i].size >= eat)
+			goto pull_pages;
+		eat -= skb_shinfo(skb)->frags[i].size;
+	}
+
+	/* If we need update frag list, we are in troubles.
+	 * Certainly, it possible to add an offset to skb data,
+	 * but taking into account that pulling is expected to
+	 * be very rare operation, it is worth to fight against
+	 * further bloating skb head and crucify ourselves here instead.
+	 * Pure masohism, indeed. 8)8)
+	 */
+	if (eat) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+		struct sk_buff *clone = NULL;
+		struct sk_buff *insp = NULL;
+
+		do {
+			if (!list)
+				BUG();
+
+			if (list->len <= eat) {
+				/* Eaten as whole. */
+				eat -= list->len;
+				list = list->next;
+				insp = list;
+			} else {
+				/* Eaten partially. */
+
+				if (skb_shared(list)) {
+					/* Sucks! We need to fork list. :-( */
+					clone = skb_clone(list, GFP_ATOMIC);
+					if (!clone)
+						return NULL;
+					insp = list->next;
+					list = clone;
+				} else {
+					/* This may be pulled without
+					 * problems. */
+					insp = list;
+				}
+				if (!pskb_pull(list, eat)) {
+					if (clone)
+						kfree_skb(clone);
+					return NULL;
+				}
+				break;
+			}
+		} while (eat);
+
+		/* Free pulled out fragments. */
+		while ((list = skb_shinfo(skb)->frag_list) != insp) {
+			skb_shinfo(skb)->frag_list = list->next;
+			kfree_skb(list);
+		}
+		/* And insert new clone at head. */
+		if (clone) {
+			clone->next = list;
+			skb_shinfo(skb)->frag_list = clone;
+		}
+	}
+	/* Success! Now we may commit changes to skb data. */
+
+pull_pages:
+	eat = delta;
+	k = 0;
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		if (skb_shinfo(skb)->frags[i].size <= eat) {
+			put_page(skb_shinfo(skb)->frags[i].page);
+			eat -= skb_shinfo(skb)->frags[i].size;
+		} else {
+			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
+			if (eat) {
+				skb_shinfo(skb)->frags[k].page_offset += eat;
+				skb_shinfo(skb)->frags[k].size -= eat;
+				eat = 0;
+			}
+			k++;
+		}
+	}
+	skb_shinfo(skb)->nr_frags = k;
+
+	skb->tail     += delta;
+	skb->data_len -= delta;
+
+	return skb->tail;
+}
+
+/* Copy some data bits from skb to kernel buffer. */
+
+int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
+{
+	int i, copy;
+	int start = skb_headlen(skb);
+
+	if (offset > (int)skb->len - len)
+		goto fault;
+
+	/* Copy header. */
+	if ((copy = start - offset) > 0) {
+		if (copy > len)
+			copy = len;
+		memcpy(to, skb->data + offset, copy);
+		if ((len -= copy) == 0)
+			return 0;
+		offset += copy;
+		to     += copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+
+		BUG_TRAP(start <= offset + len);
+
+		end = start + skb_shinfo(skb)->frags[i].size;
+		if ((copy = end - offset) > 0) {
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+
+			vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
+			memcpy(to,
+			       vaddr + skb_shinfo(skb)->frags[i].page_offset+
+			       offset - start, copy);
+			kunmap_skb_frag(vaddr);
+
+			if ((len -= copy) == 0)
+				return 0;
+			offset += copy;
+			to     += copy;
+		}
+		start = end;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+		for (; list; list = list->next) {
+			int end;
+
+			BUG_TRAP(start <= offset + len);
+
+			end = start + list->len;
+			if ((copy = end - offset) > 0) {
+				if (copy > len)
+					copy = len;
+				if (skb_copy_bits(list, offset - start,
+						  to, copy))
+					goto fault;
+				if ((len -= copy) == 0)
+					return 0;
+				offset += copy;
+				to     += copy;
+			}
+			start = end;
+		}
+	}
+	if (!len)
+		return 0;
+
+fault:
+	return -EFAULT;
+}
+
+/* Checksum skb data. */
+
+unsigned int skb_checksum(const struct sk_buff *skb, int offset,
+			  int len, unsigned int csum)
+{
+	int start = skb_headlen(skb);
+	int i, copy = start - offset;
+	int pos = 0;
+
+	/* Checksum header. */
+	if (copy > 0) {
+		if (copy > len)
+			copy = len;
+		csum = csum_partial(skb->data + offset, copy, csum);
+		if ((len -= copy) == 0)
+			return csum;
+		offset += copy;
+		pos	= copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+
+		BUG_TRAP(start <= offset + len);
+
+		end = start + skb_shinfo(skb)->frags[i].size;
+		if ((copy = end - offset) > 0) {
+			unsigned int csum2;
+			u8 *vaddr;
+			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+			if (copy > len)
+				copy = len;
+			vaddr = kmap_skb_frag(frag);
+			csum2 = csum_partial(vaddr + frag->page_offset +
+					     offset - start, copy, 0);
+			kunmap_skb_frag(vaddr);
+			csum = csum_block_add(csum, csum2, pos);
+			if (!(len -= copy))
+				return csum;
+			offset += copy;
+			pos    += copy;
+		}
+		start = end;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+		for (; list; list = list->next) {
+			int end;
+
+			BUG_TRAP(start <= offset + len);
+
+			end = start + list->len;
+			if ((copy = end - offset) > 0) {
+				unsigned int csum2;
+				if (copy > len)
+					copy = len;
+				csum2 = skb_checksum(list, offset - start,
+						     copy, 0);
+				csum = csum_block_add(csum, csum2, pos);
+				if ((len -= copy) == 0)
+					return csum;
+				offset += copy;
+				pos    += copy;
+			}
+			start = end;
+		}
+	}
+	if (len)
+		BUG();
+
+	return csum;
+}
+
+/* Both of above in one bottle. */
+
+unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
+				    u8 *to, int len, unsigned int csum)
+{
+	int start = skb_headlen(skb);
+	int i, copy = start - offset;
+	int pos = 0;
+
+	/* Copy header. */
+	if (copy > 0) {
+		if (copy > len)
+			copy = len;
+		csum = csum_partial_copy_nocheck(skb->data + offset, to,
+						 copy, csum);
+		if ((len -= copy) == 0)
+			return csum;
+		offset += copy;
+		to     += copy;
+		pos	= copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+
+		BUG_TRAP(start <= offset + len);
+
+		end = start + skb_shinfo(skb)->frags[i].size;
+		if ((copy = end - offset) > 0) {
+			unsigned int csum2;
+			u8 *vaddr;
+			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+			if (copy > len)
+				copy = len;
+			vaddr = kmap_skb_frag(frag);
+			csum2 = csum_partial_copy_nocheck(vaddr +
+							  frag->page_offset +
+							  offset - start, to,
+							  copy, 0);
+			kunmap_skb_frag(vaddr);
+			csum = csum_block_add(csum, csum2, pos);
+			if (!(len -= copy))
+				return csum;
+			offset += copy;
+			to     += copy;
+			pos    += copy;
+		}
+		start = end;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+		for (; list; list = list->next) {
+			unsigned int csum2;
+			int end;
+
+			BUG_TRAP(start <= offset + len);
+
+			end = start + list->len;
+			if ((copy = end - offset) > 0) {
+				if (copy > len)
+					copy = len;
+				csum2 = skb_copy_and_csum_bits(list,
+							       offset - start,
+							       to, copy, 0);
+				csum = csum_block_add(csum, csum2, pos);
+				if ((len -= copy) == 0)
+					return csum;
+				offset += copy;
+				to     += copy;
+				pos    += copy;
+			}
+			start = end;
+		}
+	}
+	if (len)
+		BUG();
+	return csum;
+}
+
+void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
+{
+	unsigned int csum;
+	long csstart;
+
+	if (skb->ip_summed == CHECKSUM_HW)
+		csstart = skb->h.raw - skb->data;
+	else
+		csstart = skb_headlen(skb);
+
+	if (csstart > skb_headlen(skb))
+		BUG();
+
+	memcpy(to, skb->data, csstart);
+
+	csum = 0;
+	if (csstart != skb->len)
+		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
+					      skb->len - csstart, 0);
+
+	if (skb->ip_summed == CHECKSUM_HW) {
+		long csstuff = csstart + skb->csum;
+
+		*((unsigned short *)(to + csstuff)) = csum_fold(csum);
+	}
+}
+
+/**
+ *	skb_dequeue - remove from the head of the queue
+ *	@list: list to dequeue from
+ *
+ *	Remove the head of the list. The list lock is taken so the function
+ *	may be used safely with other locking list functions. The head item is
+ *	returned or %NULL if the list is empty.
+ */
+
+struct sk_buff *skb_dequeue(struct sk_buff_head *list)
+{
+	unsigned long flags;
+	struct sk_buff *result;
+
+	spin_lock_irqsave(&list->lock, flags);
+	result = __skb_dequeue(list);
+	spin_unlock_irqrestore(&list->lock, flags);
+	return result;
+}
+
+/**
+ *	skb_dequeue_tail - remove from the tail of the queue
+ *	@list: list to dequeue from
+ *
+ *	Remove the tail of the list. The list lock is taken so the function
+ *	may be used safely with other locking list functions. The tail item is
+ *	returned or %NULL if the list is empty.
+ */
+struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
+{
+	unsigned long flags;
+	struct sk_buff *result;
+
+	spin_lock_irqsave(&list->lock, flags);
+	result = __skb_dequeue_tail(list);
+	spin_unlock_irqrestore(&list->lock, flags);
+	return result;
+}
+
+/**
+ *	skb_queue_purge - empty a list
+ *	@list: list to empty
+ *
+ *	Delete all buffers on an &sk_buff list. Each buffer is removed from
+ *	the list and one reference dropped. This function takes the list
+ *	lock and is atomic with respect to other list locking functions.
+ */
+void skb_queue_purge(struct sk_buff_head *list)
+{
+	struct sk_buff *skb;
+	while ((skb = skb_dequeue(list)) != NULL)
+		kfree_skb(skb);
+}
+
+/**
+ *	skb_queue_head - queue a buffer at the list head
+ *	@list: list to use
+ *	@newsk: buffer to queue
+ *
+ *	Queue a buffer at the start of the list. This function takes the
+ *	list lock and can be used safely with other locking &sk_buff functions
+ *	safely.
+ *
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&list->lock, flags);
+	__skb_queue_head(list, newsk);
+	spin_unlock_irqrestore(&list->lock, flags);
+}
+
+/**
+ *	skb_queue_tail - queue a buffer at the list tail
+ *	@list: list to use
+ *	@newsk: buffer to queue
+ *
+ *	Queue a buffer at the tail of the list. This function takes the
+ *	list lock and can be used safely with other locking &sk_buff functions
+ *	safely.
+ *
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&list->lock, flags);
+	__skb_queue_tail(list, newsk);
+	spin_unlock_irqrestore(&list->lock, flags);
+}
+/**
+ *	skb_unlink	-	remove a buffer from a list
+ *	@skb: buffer to remove
+ *
+ *	Place a packet after a given packet in a list. The list locks are taken
+ *	and this function is atomic with respect to other list locked calls
+ *
+ *	Works even without knowing the list it is sitting on, which can be
+ *	handy at times. It also means that THE LIST MUST EXIST when you
+ *	unlink. Thus a list must have its contents unlinked before it is
+ *	destroyed.
+ */
+void skb_unlink(struct sk_buff *skb)
+{
+	struct sk_buff_head *list = skb->list;
+
+	if (list) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&list->lock, flags);
+		if (skb->list == list)
+			__skb_unlink(skb, skb->list);
+		spin_unlock_irqrestore(&list->lock, flags);
+	}
+}
+
+
+/**
+ *	skb_append	-	append a buffer
+ *	@old: buffer to insert after
+ *	@newsk: buffer to insert
+ *
+ *	Place a packet after a given packet in a list. The list locks are taken
+ *	and this function is atomic with respect to other list locked calls.
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+
+void skb_append(struct sk_buff *old, struct sk_buff *newsk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&old->list->lock, flags);
+	__skb_append(old, newsk);
+	spin_unlock_irqrestore(&old->list->lock, flags);
+}
+
+
+/**
+ *	skb_insert	-	insert a buffer
+ *	@old: buffer to insert before
+ *	@newsk: buffer to insert
+ *
+ *	Place a packet before a given packet in a list. The list locks are taken
+ *	and this function is atomic with respect to other list locked calls
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+
+void skb_insert(struct sk_buff *old, struct sk_buff *newsk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&old->list->lock, flags);
+	__skb_insert(newsk, old->prev, old, old->list);
+	spin_unlock_irqrestore(&old->list->lock, flags);
+}
+
+#if 0
+/*
+ * 	Tune the memory allocator for a new MTU size.
+ */
+void skb_add_mtu(int mtu)
+{
+	/* Must match allocation in alloc_skb */
+	mtu = SKB_DATA_ALIGN(mtu) + sizeof(struct skb_shared_info);
+
+	kmem_add_cache_size(mtu);
+}
+#endif
+
+static inline void skb_split_inside_header(struct sk_buff *skb,
+					   struct sk_buff* skb1,
+					   const u32 len, const int pos)
+{
+	int i;
+
+	memcpy(skb_put(skb1, pos - len), skb->data + len, pos - len);
+
+	/* And move data appendix as is. */
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
+
+	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb1->data_len		   = skb->data_len;
+	skb1->len		   += skb1->data_len;
+	skb->data_len		   = 0;
+	skb->len		   = len;
+	skb->tail		   = skb->data + len;
+}
+
+static inline void skb_split_no_header(struct sk_buff *skb,
+				       struct sk_buff* skb1,
+				       const u32 len, int pos)
+{
+	int i, k = 0;
+	const int nfrags = skb_shinfo(skb)->nr_frags;
+
+	skb_shinfo(skb)->nr_frags = 0;
+	skb1->len		  = skb1->data_len = skb->len - len;
+	skb->len		  = len;
+	skb->data_len		  = len - pos;
+
+	for (i = 0; i < nfrags; i++) {
+		int size = skb_shinfo(skb)->frags[i].size;
+
+		if (pos + size > len) {
+			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
+
+			if (pos < len) {
+				/* Split frag.
+				 * We have two variants in this case:
+				 * 1. Move all the frag to the second
+				 *    part, if it is possible. F.e.
+				 *    this approach is mandatory for TUX,
+				 *    where splitting is expensive.
+				 * 2. Split is accurately. We make this.
+				 */
+				get_page(skb_shinfo(skb)->frags[i].page);
+				skb_shinfo(skb1)->frags[0].page_offset += len - pos;
+				skb_shinfo(skb1)->frags[0].size -= len - pos;
+				skb_shinfo(skb)->frags[i].size	= len - pos;
+				skb_shinfo(skb)->nr_frags++;
+			}
+			k++;
+		} else
+			skb_shinfo(skb)->nr_frags++;
+		pos += size;
+	}
+	skb_shinfo(skb1)->nr_frags = k;
+}
+
+/**
+ * skb_split - Split fragmented skb to two parts at length len.
+ * @skb: the buffer to split
+ * @skb1: the buffer to receive the second part
+ * @len: new length for skb
+ */
+void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
+{
+	int pos = skb_headlen(skb);
+
+	if (len < pos)	/* Split line is inside header. */
+		skb_split_inside_header(skb, skb1, len, pos);
+	else		/* Second chunk has no header, nothing to copy. */
+		skb_split_no_header(skb, skb1, len, pos);
+}
+
+void __init skb_init(void)
+{
+	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
+					      sizeof(struct sk_buff),
+					      0,
+					      SLAB_HWCACHE_ALIGN,
+					      NULL, NULL);
+	if (!skbuff_head_cache)
+		panic("cannot create skbuff cache");
+}
+
+EXPORT_SYMBOL(___pskb_trim);
+EXPORT_SYMBOL(__kfree_skb);
+EXPORT_SYMBOL(__pskb_pull_tail);
+EXPORT_SYMBOL(alloc_skb);
+EXPORT_SYMBOL(pskb_copy);
+EXPORT_SYMBOL(pskb_expand_head);
+EXPORT_SYMBOL(skb_checksum);
+EXPORT_SYMBOL(skb_clone);
+EXPORT_SYMBOL(skb_clone_fraglist);
+EXPORT_SYMBOL(skb_copy);
+EXPORT_SYMBOL(skb_copy_and_csum_bits);
+EXPORT_SYMBOL(skb_copy_and_csum_dev);
+EXPORT_SYMBOL(skb_copy_bits);
+EXPORT_SYMBOL(skb_copy_expand);
+EXPORT_SYMBOL(skb_over_panic);
+EXPORT_SYMBOL(skb_pad);
+EXPORT_SYMBOL(skb_realloc_headroom);
+EXPORT_SYMBOL(skb_under_panic);
+EXPORT_SYMBOL(skb_dequeue);
+EXPORT_SYMBOL(skb_dequeue_tail);
+EXPORT_SYMBOL(skb_insert);
+EXPORT_SYMBOL(skb_queue_purge);
+EXPORT_SYMBOL(skb_queue_head);
+EXPORT_SYMBOL(skb_queue_tail);
+EXPORT_SYMBOL(skb_unlink);
+EXPORT_SYMBOL(skb_append);
+EXPORT_SYMBOL(skb_split);