/*
* Definitions for the 'struct sk_buff' memory handlers.
*
* Authors:
* Alan Cox, <gw4pts@gw4pts.ampr.org>
* Florian La Roche, <rzsfl@rz.uni-sb.de>
*
* 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.
*/
#ifndef _LINUX_SKBUFF_H
#define _LINUX_SKBUFF_H
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/time.h>
#include <linux/cache.h>
#include <asm/atomic.h>
#include <asm/types.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/poll.h>
#include <linux/net.h>
#include <net/checksum.h>
#define HAVE_ALLOC_SKB /* For the drivers to know */
#define HAVE_ALIGNABLE_SKB /* Ditto 8) */
#define SLAB_SKB /* Slabified skbuffs */
#define CHECKSUM_NONE 0
#define CHECKSUM_HW 1
#define CHECKSUM_UNNECESSARY 2
#define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
~(SMP_CACHE_BYTES - 1))
#define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \
sizeof(struct skb_shared_info)) & \
~(SMP_CACHE_BYTES - 1))
#define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
#define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
/* A. Checksumming of received packets by device.
*
* NONE: device failed to checksum this packet.
* skb->csum is undefined.
*
* UNNECESSARY: device parsed packet and wouldbe verified checksum.
* skb->csum is undefined.
* It is bad option, but, unfortunately, many of vendors do this.
* Apparently with secret goal to sell you new device, when you
* will add new protocol to your host. F.e. IPv6. 8)
*
* HW: the most generic way. Device supplied checksum of _all_
* the packet as seen by netif_rx in skb->csum.
* NOTE: Even if device supports only some protocols, but
* is able to produce some skb->csum, it MUST use HW,
* not UNNECESSARY.
*
* B. Checksumming on output.
*
* NONE: skb is checksummed by protocol or csum is not required.
*
* HW: device is required to csum packet as seen by hard_start_xmit
* from skb->h.raw to the end and to record the checksum
* at skb->h.raw+skb->csum.
*
* Device must show its capabilities in dev->features, set
* at device setup time.
* NETIF_F_HW_CSUM - it is clever device, it is able to checksum
* everything.
* NETIF_F_NO_CSUM - loopback or reliable single hop media.
* NETIF_F_IP_CSUM - device is dumb. It is able to csum only
* TCP/UDP over IPv4. Sigh. Vendors like this
* way by an unknown reason. Though, see comment above
* about CHECKSUM_UNNECESSARY. 8)
*
* Any questions? No questions, good. --ANK
*/
#ifdef __i386__
#define NET_CALLER(arg) (*(((void **)&arg) - 1))
#else
#define NET_CALLER(arg) __builtin_return_address(0)
#endif
struct net_device;
#ifdef CONFIG_NETFILTER
struct nf_conntrack {
atomic_t use;
void (*destroy)(struct nf_conntrack *);
};
#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info {
atomic_t use;
struct net_device *physindev;
struct net_device *physoutdev;
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
struct net_device *netoutdev;
#endif
unsigned int mask;
unsigned long data[32 / sizeof(unsigned long)];
};
#endif
#endif
struct sk_buff_head {
/* These two members must be first. */
struct sk_buff *next;
struct sk_buff *prev;
__u32 qlen;
spinlock_t lock;
};
struct sk_buff;
/* To allow 64K frame to be packed as single skb without frag_list */
#define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
typedef struct skb_frag_struct skb_frag_t;
struct skb_frag_struct {
struct page *page;
__u16 page_offset;
__u16 size;
};
/* This data is invariant across clones and lives at
* the end of the header data, ie. at skb->end.
*/
struct skb_shared_info {
atomic_t dataref;
unsigned int nr_frags;
unsigned short tso_size;
unsigned short tso_segs;
struct sk_buff *frag_list;
skb_frag_t frags[MAX_SKB_FRAGS];
};
/* We divide dataref into two halves. The higher 16 bits hold references
* to the payload part of skb->data. The lower 16 bits hold references to
* the entire skb->data. It is up to the users of the skb to agree on
* where the payload starts.
*
* All users must obey the rule that the skb->data reference count must be
* greater than or equal to the payload reference count.
*
* Holding a reference to the payload part means that the user does not
* care about modifications to the header part of skb->data.
*/
#define SKB_DATAREF_SHIFT 16
#define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
/**
* struct sk_buff - socket buffer
* @next: Next buffer in list
* @prev: Previous buffer in list
* @list: List we are on
* @sk: Socket we are owned by
* @stamp: Time we arrived
* @dev: Device we arrived on/are leaving by
* @input_dev: Device we arrived on
* @real_dev: The real device we are using
* @h: Transport layer header
* @nh: Network layer header
* @mac: Link layer header
* @dst: FIXME: Describe this field
* @cb: Control buffer. Free for use by every layer. Put private vars here
* @len: Length of actual data
* @data_len: Data length
* @mac_len: Length of link layer header
* @csum: Checksum
* @__unused: Dead field, may be reused
* @cloned: Head may be cloned (check refcnt to be sure)
* @nohdr: Payload reference only, must not modify header
* @pkt_type: Packet class
* @ip_summed: Driver fed us an IP checksum
* @priority: Packet queueing priority
* @users: User count - see {datagram,tcp}.c
* @protocol: Packet protocol from driver
* @security: Security level of packet
* @truesize: Buffer size
* @head: Head of buffer
* @data: Data head pointer
* @tail: Tail pointer
* @end: End pointer
* @destructor: Destruct function
* @nfmark: Can be used for communication between hooks
* @nfcache: Cache info
* @nfct: Associated connection, if any
* @nfctinfo: Relationship of this skb to the connection
* @nf_debug: Netfilter debugging
* @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
* @private: Data which is private to the HIPPI implementation
* @tc_index: Traffic control index
* @tc_verd: traffic control verdict
* @tc_classid: traffic control classid
*/
struct sk_buff {
/* These two members must be first. */
struct sk_buff *next;
struct sk_buff *prev;
struct sk_buff_head *list;
struct sock *sk;
struct timeval stamp;
struct net_device *dev;
struct net_device *input_dev;
struct net_device *real_dev;
union {
struct tcphdr *th;
struct udphdr *uh;
struct icmphdr *icmph;
struct igmphdr *igmph;
struct iphdr *ipiph;
struct ipv6hdr *ipv6h;
unsigned char *raw;
} h;
union {
struct iphdr *iph;
struct ipv6hdr *ipv6h;
struct arphdr *arph;
unsigned char *raw;
} nh;
union {
unsigned char *raw;
} mac;
struct dst_entry *dst;
struct sec_path *sp;
/*
* This is the control buffer. It is free to use for every
* layer. Please put your private variables there. If you
* want to keep them across layers you have to do a skb_clone()
* first. This is owned by whoever has the skb queued ATM.
*/
char cb[40];
unsigned int len,
data_len,
mac_len,
csum;
unsigned char local_df,
cloned:1,
nohdr:1,
pkt_type,
ip_summed;
__u32 priority;
unsigned short protocol,
security;
void (*destructor)(struct sk_buff *skb);
#ifdef CONFIG_NETFILTER
unsigned long nfmark;
__u32 nfcache;
__u32 nfctinfo;
struct nf_conntrack *nfct;
#ifdef CONFIG_NETFILTER_DEBUG
unsigned int nf_debug;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info *nf_bridge;
#endif
#endif /* CONFIG_NETFILTER */
#if defined(CONFIG_HIPPI)
union {
__u32 ifield;
} private;
#endif
#ifdef CONFIG_NET_SCHED
__u32 tc_index; /* traffic control index */
#ifdef CONFIG_NET_CLS_ACT
__u32 tc_verd; /* traffic control verdict */
__u32 tc_classid; /* traffic control classid */
#endif
#endif
/* These elements must be at the end, see alloc_skb() for details. */
unsigned int truesize;
atomic_t users;
unsigned char *head,
*data,
*tail,
*end;
};
#ifdef __KERNEL__
/*
* Handling routines are only of interest to the kernel
*/
#include <linux/slab.h>
#include <asm/system.h>
extern void __kfree_skb(struct sk_buff *skb);
extern struct sk_buff *alloc_skb(unsigned int size, int priority);
extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
unsigned int size, int priority);
extern void kfree_skbmem(struct sk_buff *skb);
extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
extern int pskb_expand_head(struct sk_buff *skb,
int nhead, int ntail, int gfp_mask);
extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
unsigned int headroom);
extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
int newheadroom, int newtailroom,
int priority);
extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
#define dev_kfree_skb(a) kfree_skb(a)
extern void skb_over_panic(struct sk_buff *skb, int len,
void *here);
extern void skb_under_panic(struct sk_buff *skb, int len,
void *here);
/* Internal */
#define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
/**
* skb_queue_empty - check if a queue is empty
* @list: queue head
*
* Returns true if the queue is empty, false otherwise.
*/
static inline int skb_queue_empty(const struct sk_buff_head *list)
{
return list->next == (struct sk_buff *)list;
}
/**
* skb_get - reference buffer
* @skb: buffer to reference
*
* Makes another reference to a socket buffer and returns a pointer
* to the buffer.
*/
static inline struct sk_buff *skb_get(struct sk_buff *skb)
{
atomic_inc(&skb->users);
return skb;
}
/*
* If users == 1, we are the only owner and are can avoid redundant
* atomic change.
*/
/**
* kfree_skb - free an sk_buff
* @skb: buffer to free
*
* Drop a reference to the buffer and free it if the usage count has
* hit zero.
*/
static inline void kfree_skb(struct sk_buff *skb)
{
if (likely(atomic_read(&skb->users) == 1))
smp_rmb();
else if (likely(!atomic_dec_and_test(&skb->users)))
return;
__kfree_skb(skb);
}
/**
* skb_cloned - is the buffer a clone
* @skb: buffer to check
*
* Returns true if the buffer was generated with skb_clone() and is
* one of multiple shared copies of the buffer. Cloned buffers are
* shared data so must not be written to under normal circumstances.
*/
static inline int skb_cloned(const struct sk_buff *skb)
{
return skb->cloned &&
(atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
}
/**
* skb_header_cloned - is the header a clone
* @skb: buffer to check
*
* Returns true if modifying the header part of the buffer requires
* the data to be copied.
*/
static inline int skb_header_cloned(const struct sk_buff *skb)
{
int dataref;
if (!skb->cloned)
return 0;
dataref = atomic_read(&skb_shinfo(skb)->dataref);
dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
return dataref != 1;
}
/**
* skb_header_release - release reference to header
* @skb: buffer to operate on
*
* Drop a reference to the header part of the buffer. This is done
* by acquiring a payload reference. You must not read from the header
* part of skb->data after this.
*/
static inline void skb_header_release(struct sk_buff *skb)
{
BUG_ON(skb->nohdr);
skb->nohdr = 1;
atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
}
/**
* skb_shared - is the buffer shared
* @skb: buffer to check
*
* Returns true if more than one person has a reference to this
* buffer.
*/
static inline int skb_shared(const struct sk_buff *skb)
{
return atomic_read(&skb->users) != 1;
}
/**
* skb_share_check - check if buffer is shared and if so clone it
* @skb: buffer to check
* @pri: priority for memory allocation
*
* If the buffer is shared the buffer is cloned and the old copy
* drops a reference. A new clone with a single reference is returned.
* If the buffer is not shared the original buffer is returned. When
* being called from interrupt status or with spinlocks held pri must
* be GFP_ATOMIC.
*
* NULL is returned on a memory allocation failure.
*/
static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri)
{
might_sleep_if(pri & __GFP_WAIT);
if (skb_shared(skb)) {
struct sk_buff *nskb = skb_clone(skb, pri);
kfree_skb(skb);
skb = nskb;
}
return skb;
}
/*
* Copy shared buffers into a new sk_buff. We effectively do COW on
* packets to handle cases where we have a local reader and forward
* and a couple of other messy ones. The normal one is tcpdumping
* a packet thats being forwarded.
*/
/**
* skb_unshare - make a copy of a shared buffer
* @skb: buffer to check
* @pri: priority for memory allocation
*
* If the socket buffer is a clone then this function creates a new
* copy of the data, drops a reference count on the old copy and returns
* the new copy with the reference count at 1. If the buffer is not a clone
* the original buffer is returned. When called with a spinlock held or
* from interrupt state @pri must be %GFP_ATOMIC
*
* %NULL is returned on a memory allocation failure.
*/
static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri)
{
might_sleep_if(pri & __GFP_WAIT);
if (skb_cloned(skb)) {
struct sk_buff *nskb = skb_copy(skb, pri);
kfree_skb(skb); /* Free our shared copy */
skb = nskb;
}
return skb;
}
/**
* skb_peek
* @list_: list to peek at
*
* Peek an &sk_buff. Unlike most other operations you _MUST_
* be careful with this one. A peek leaves the buffer on the
* list and someone else may run off with it. You must hold
* the appropriate locks or have a private queue to do this.
*
* Returns %NULL for an empty list or a pointer to the head element.
* The reference count is not incremented and the reference is therefore
* volatile. Use with caution.
*/
static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
{
struct sk_buff *list = ((struct sk_buff *)list_)->next;
if (list == (struct sk_buff *)list_)
list = NULL;
return list;
}
/**
* skb_peek_tail
* @list_: list to peek at
*
* Peek an &sk_buff. Unlike most other operations you _MUST_
* be careful with this one. A peek leaves the buffer on the
* list and someone else may run off with it. You must hold
* the appropriate locks or have a private queue to do this.
*
* Returns %NULL for an empty list or a pointer to the tail element.
* The reference count is not incremented and the reference is therefore
* volatile. Use with caution.
*/
static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
{
struct sk_buff *list = ((struct sk_buff *)list_)->prev;
if (list == (struct sk_buff *)list_)
list = NULL;
return list;
}
/**
* skb_queue_len - get queue length
* @list_: list to measure
*
* Return the length of an &sk_buff queue.
*/
static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
{
return list_->qlen;
}
static inline void skb_queue_head_init(struct sk_buff_head *list)
{
spin_lock_init(&list->lock);
list->prev = list->next = (struct sk_buff *)list;
list->qlen = 0;
}
/*
* Insert an sk_buff at the start of a list.
*
* The "__skb_xxxx()" functions are the non-atomic ones that
* can only be called with interrupts disabled.
*/
/**
* __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 a list. This function takes no locks
* and you must therefore hold required locks before calling it.
*
* A buffer cannot be placed on two lists at the same time.
*/
extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
static inline void __skb_queue_head(struct sk_buff_head *list,
struct sk_buff *newsk)
{
struct sk_buff *prev, *next;
newsk->list = list;
list->qlen++;
prev = (struct sk_buff *)list;
next = prev->next;
newsk->next = next;
newsk->prev = prev;
next->prev = prev->next = newsk;
}
/**
* __skb_queue_tail - queue a buffer at the list tail
* @list: list to use
* @newsk: buffer to queue
*
* Queue a buffer at the end of a list. This function takes no locks
* and you must therefore hold required locks before calling it.
*
* A buffer cannot be placed on two lists at the same time.
*/
extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
static inline void __skb_queue_tail(struct sk_buff_head *list,
struct sk_buff *newsk)
{
struct sk_buff *prev, *next;
newsk->list = list;
list->qlen++;
next = (struct sk_buff *)list;
prev = next->prev;
newsk->next = next;
newsk->prev = prev;
next->prev = prev->next = newsk;
}
/**
* __skb_dequeue - remove from the head of the queue
* @list: list to dequeue from
*
* Remove the head of the list. This function does not take any locks
* so must be used with appropriate locks held only. The head item is
* returned or %NULL if the list is empty.
*/
extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
{
struct sk_buff *next, *prev, *result;
prev = (struct sk_buff *) list;
next = prev->next;
result = NULL;
if (next != prev) {
result = next;
next = next->next;
list->qlen--;
next->prev = prev;
prev->next = next;
result->next = result->prev = NULL;
result->list = NULL;
}
return result;
}
/*
* Insert a packet on a list.
*/
extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk);
static inline void __skb_insert(struct sk_buff *newsk,
struct sk_buff *prev, struct sk_buff *next,
struct sk_buff_head *list)
{
newsk->next = next;
newsk->prev = prev;
next->prev = prev->next = newsk;
newsk->list = list;
list->qlen++;
}
/*
* Place a packet after a given packet in a list.
*/
extern void skb_append(struct sk_buff *old, struct sk_buff *newsk);
static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk)
{
__skb_insert(newsk, old, old->next, old->list);
}
/*
* remove sk_buff from list. _Must_ be called atomically, and with
* the list known..
*/
extern void skb_unlink(struct sk_buff *skb);
static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
{
struct sk_buff *next, *prev;
list->qlen--;
next = skb->next;
prev = skb->prev;
skb->next = skb->prev = NULL;
skb->list = NULL;
next->prev = prev;
prev->next = next;
}
/* XXX: more streamlined implementation */
/**
* __skb_dequeue_tail - remove from the tail of the queue
* @list: list to dequeue from
*
* Remove the tail of the list. This function does not take any locks
* so must be used with appropriate locks held only. The tail item is
* returned or %NULL if the list is empty.
*/
extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
{
struct sk_buff *skb = skb_peek_tail(list);
if (skb)
__skb_unlink(skb, list);
return skb;
}
static inline int skb_is_nonlinear(const struct sk_buff *skb)
{
return skb->data_len;
}
static inline unsigned int skb_headlen(const struct sk_buff *skb)
{
return skb->len - skb->data_len;
}
static inline int skb_pagelen(const struct sk_buff *skb)
{
int i, len = 0;
for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
len += skb_shinfo(skb)->frags[i].size;
return len + skb_headlen(skb);
}
static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
struct page *page, int off, int size)
{
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
frag->page = page;
frag->page_offset = off;
frag->size = size;
skb_shinfo(skb)->nr_frags = i + 1;
}
#define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
#define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
#define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
/*
* Add data to an sk_buff
*/
static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
{
unsigned char *tmp = skb->tail;
SKB_LINEAR_ASSERT(skb);
skb->tail += len;
skb->len += len;
return tmp;
}
/**
* skb_put - add data to a buffer
* @skb: buffer to use
* @len: amount of data to add
*
* This function extends the used data area of the buffer. If this would
* exceed the total buffer size the kernel will panic. A pointer to the
* first byte of the extra data is returned.
*/
static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
{
unsigned char *tmp = skb->tail;
SKB_LINEAR_ASSERT(skb);
skb->tail += len;
skb->len += len;
if (unlikely(skb->tail>skb->end))
skb_over_panic(skb, len, current_text_addr());
return tmp;
}
static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
{
skb->data -= len;
skb->len += len;
return skb->data;
}
/**
* skb_push - add data to the start of a buffer
* @skb: buffer to use
* @len: amount of data to add
*
* This function extends the used data area of the buffer at the buffer
* start. If this would exceed the total buffer headroom the kernel will
* panic. A pointer to the first byte of the extra data is returned.
*/
static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
{
skb->data -= len;
skb->len += len;
if (unlikely(skb->data<skb->head))
skb_under_panic(skb, len, current_text_addr());
return skb->data;
}
static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
{
skb->len -= len;
BUG_ON(skb->len < skb->data_len);
return skb->data += len;
}
/**
* skb_pull - remove data from the start of a buffer
* @skb: buffer to use
* @len: amount of data to remove
*
* This function removes data from the start of a buffer, returning
* the memory to the headroom. A pointer to the next data in the buffer
* is returned. Once the data has been pulled future pushes will overwrite
* the old data.
*/
static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
{
return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
}
extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
{
if (len > skb_headlen(skb) &&
!__pskb_pull_tail(skb, len-skb_headlen(skb)))
return NULL;
skb->len -= len;
return skb->data += len;
}
static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
{
return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
}
static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
{
if (likely(len <= skb_headlen(skb)))
return 1;
if (unlikely(len > skb->len))
return 0;
return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
}
/**
* skb_headroom - bytes at buffer head
* @skb: buffer to check
*
* Return the number of bytes of free space at the head of an &sk_buff.
*/
static inline int skb_headroom(const struct sk_buff *skb)
{
return skb->data - skb->head;
}
/**
* skb_tailroom - bytes at buffer end
* @skb: buffer to check
*
* Return the number of bytes of free space at the tail of an sk_buff
*/
static inline int skb_tailroom(const struct sk_buff *skb)
{
return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
}
/**
* skb_reserve - adjust headroom
* @skb: buffer to alter
* @len: bytes to move
*
* Increase the headroom of an empty &sk_buff by reducing the tail
* room. This is only allowed for an empty buffer.
*/
static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
{
skb->data += len;
skb->tail += len;
}
/*
* CPUs often take a performance hit when accessing unaligned memory
* locations. The actual performance hit varies, it can be small if the
* hardware handles it or large if we have to take an exception and fix it
* in software.
*
* Since an ethernet header is 14 bytes network drivers often end up with
* the IP header at an unaligned offset. The IP header can be aligned by
* shifting the start of the packet by 2 bytes. Drivers should do this
* with:
*
* skb_reserve(NET_IP_ALIGN);
*
* The downside to this alignment of the IP header is that the DMA is now
* unaligned. On some architectures the cost of an unaligned DMA is high
* and this cost outweighs the gains made by aligning the IP header.
*
* Since this trade off varies between architectures, we allow NET_IP_ALIGN
* to be overridden.
*/
#ifndef NET_IP_ALIGN
#define NET_IP_ALIGN 2
#endif
extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
{
if (!skb->data_len) {
skb->len = len;
skb->tail = skb->data + len;
} else
___pskb_trim(skb, len, 0);
}
/**
* skb_trim - remove end from a buffer
* @skb: buffer to alter
* @len: new length
*
* Cut the length of a buffer down by removing data from the tail. If
* the buffer is already under the length specified it is not modified.
*/
static inline void skb_trim(struct sk_buff *skb, unsigned int len)
{
if (skb->len > len)
__skb_trim(skb, len);
}
static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
{
if (!skb->data_len) {
skb->len = len;
skb->tail = skb->data+len;
return 0;
}
return ___pskb_trim(skb, len, 1);
}
static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
{
return (len < skb->len) ? __pskb_trim(skb, len) : 0;
}
/**
* skb_orphan - orphan a buffer
* @skb: buffer to orphan
*
* If a buffer currently has an owner then we call the owner's
* destructor function and make the @skb unowned. The buffer continues
* to exist but is no longer charged to its former owner.
*/
static inline void skb_orphan(struct sk_buff *skb)
{
if (skb->destructor)
skb->destructor(skb);
skb->destructor = NULL;
skb->sk = NULL;
}
/**
* __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 does not take the
* list lock and the caller must hold the relevant locks to use it.
*/
extern void skb_queue_purge(struct sk_buff_head *list);
static inline void __skb_queue_purge(struct sk_buff_head *list)
{
struct sk_buff *skb;
while ((skb = __skb_dequeue(list)) != NULL)
kfree_skb(skb);
}
/**
* __dev_alloc_skb - allocate an skbuff for sending
* @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 in there is no free memory.
*/
#ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
int gfp_mask)
{
struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
if (likely(skb))
skb_reserve(skb, 16);
return skb;
}
#else
extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask);
#endif
/**
* dev_alloc_skb - allocate an skbuff for sending
* @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 in there is no free memory. Although this function
* allocates memory it can be called from an interrupt.
*/
static inline struct sk_buff *dev_alloc_skb(unsigned int length)
{
return __dev_alloc_skb(length, GFP_ATOMIC);
}
/**
* skb_cow - copy header of skb when it is required
* @skb: buffer to cow
* @headroom: needed headroom
*
* If the skb passed lacks sufficient headroom or its data part
* is shared, data is reallocated. If reallocation fails, an error
* is returned and original skb is not changed.
*
* The result is skb with writable area skb->head...skb->tail
* and at least @headroom of space at head.
*/
static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
{
int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb);
if (delta < 0)
delta = 0;
if (delta || skb_cloned(skb))
return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC);
return 0;
}
/**
* skb_padto - pad an skbuff up to a minimal size
* @skb: buffer to pad
* @len: minimal length
*
* Pads up a buffer to ensure the trailing bytes exist and are
* blanked. If the buffer already contains sufficient data it
* is untouched. Returns the buffer, which may be a replacement
* for the original, or NULL for out of memory - in which case
* the original buffer is still freed.
*/
static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
{
unsigned int size = skb->len;
if (likely(size >= len))
return skb;
return skb_pad(skb, len-size);
}
static inline int skb_add_data(struct sk_buff *skb,
char __user *from, int copy)
{
const int off = skb->len;
if (skb->ip_summed == CHECKSUM_NONE) {
int err = 0;
unsigned int csum = csum_and_copy_from_user(from,
skb_put(skb, copy),
copy, 0, &err);
if (!err) {
skb->csum = csum_block_add(skb->csum, csum, off);
return 0;
}
} else if (!copy_from_user(skb_put(skb, copy), from, copy))
return 0;
__skb_trim(skb, off);
return -EFAULT;
}
static inline int skb_can_coalesce(struct sk_buff *skb, int i,
struct page *page, int off)
{
if (i) {
struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
return page == frag->page &&
off == frag->page_offset + frag->size;
}
return 0;
}
/**
* skb_linearize - convert paged skb to linear one
* @skb: buffer to linarize
* @gfp: allocation mode
*
* If there is no free memory -ENOMEM is returned, otherwise zero
* is returned and the old skb data released.
*/
extern int __skb_linearize(struct sk_buff *skb, int gfp);
static inline int skb_linearize(struct sk_buff *skb, int gfp)
{
return __skb_linearize(skb, gfp);
}
/**
* skb_postpull_rcsum - update checksum for received skb after pull
* @skb: buffer to update
* @start: start of data before pull
* @len: length of data pulled
*
* After doing a pull on a received packet, you need to call this to
* update the CHECKSUM_HW checksum, or set ip_summed to CHECKSUM_NONE
* so that it can be recomputed from scratch.
*/
static inline void skb_postpull_rcsum(struct sk_buff *skb,
const void *start, int len)
{
if (skb->ip_summed == CHECKSUM_HW)
skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
}
/**
* pskb_trim_rcsum - trim received skb and update checksum
* @skb: buffer to trim
* @len: new length
*
* This is exactly the same as pskb_trim except that it ensures the
* checksum of received packets are still valid after the operation.
*/
static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
{
if (len >= skb->len)
return 0;
if (skb->ip_summed == CHECKSUM_HW)
skb->ip_summed = CHECKSUM_NONE;
return __pskb_trim(skb, len);
}
static inline void *kmap_skb_frag(const skb_frag_t *frag)
{
#ifdef CONFIG_HIGHMEM
BUG_ON(in_irq());
local_bh_disable();
#endif
return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ);
}
static inline void kunmap_skb_frag(void *vaddr)
{
kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
#ifdef CONFIG_HIGHMEM
local_bh_enable();
#endif
}
#define skb_queue_walk(queue, skb) \
for (skb = (queue)->next; \
prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
skb = skb->next)
extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
int noblock, int *err);
extern unsigned int datagram_poll(struct file *file, struct socket *sock,
struct poll_table_struct *wait);
extern int skb_copy_datagram_iovec(const struct sk_buff *from,
int offset, struct iovec *to,
int size);
extern int skb_copy_and_csum_datagram_iovec(const
struct sk_buff *skb,
int hlen,
struct iovec *iov);
extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
extern unsigned int skb_checksum(const struct sk_buff *skb, int offset,
int len, unsigned int csum);
extern int skb_copy_bits(const struct sk_buff *skb, int offset,
void *to, int len);
extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb,
int offset, u8 *to, int len,
unsigned int csum);
extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
extern void skb_split(struct sk_buff *skb,
struct sk_buff *skb1, const u32 len);
static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
int len, void *buffer)
{
int hlen = skb_headlen(skb);
if (offset + len <= hlen)
return skb->data + offset;
if (skb_copy_bits(skb, offset, buffer, len) < 0)
return NULL;
return buffer;
}
extern void skb_init(void);
extern void skb_add_mtu(int mtu);
#ifdef CONFIG_NETFILTER
static inline void nf_conntrack_put(struct nf_conntrack *nfct)
{
if (nfct && atomic_dec_and_test(&nfct->use))
nfct->destroy(nfct);
}
static inline void nf_conntrack_get(struct nf_conntrack *nfct)
{
if (nfct)
atomic_inc(&nfct->use);
}
static inline void nf_reset(struct sk_buff *skb)
{
nf_conntrack_put(skb->nfct);
skb->nfct = NULL;
#ifdef CONFIG_NETFILTER_DEBUG
skb->nf_debug = 0;
#endif
}
static inline void nf_reset_debug(struct sk_buff *skb)
{
#ifdef CONFIG_NETFILTER_DEBUG
skb->nf_debug = 0;
#endif
}
#ifdef CONFIG_BRIDGE_NETFILTER
static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
{
if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
kfree(nf_bridge);
}
static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
{
if (nf_bridge)
atomic_inc(&nf_bridge->use);
}
#endif /* CONFIG_BRIDGE_NETFILTER */
#else /* CONFIG_NETFILTER */
static inline void nf_reset(struct sk_buff *skb) {}
#endif /* CONFIG_NETFILTER */
#endif /* __KERNEL__ */
#endif /* _LINUX_SKBUFF_H */
