skbuff.h 57.5 KB
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/*
 *	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/kernel.h>
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#include <linux/kmemcheck.h>
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#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/net.h>
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#include <linux/textsearch.h>
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#include <net/checksum.h>
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#include <linux/rcupdate.h>
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#include <linux/dmaengine.h>
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#include <linux/hrtimer.h>
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/* Don't change this without changing skb_csum_unnecessary! */
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#define CHECKSUM_NONE 0
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#define CHECKSUM_UNNECESSARY 1
#define CHECKSUM_COMPLETE 2
#define CHECKSUM_PARTIAL 3
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#define SKB_DATA_ALIGN(X)	(((X) + (SMP_CACHE_BYTES - 1)) & \
				 ~(SMP_CACHE_BYTES - 1))
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#define SKB_WITH_OVERHEAD(X)	\
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	((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
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#define SKB_MAX_ORDER(X, ORDER) \
	SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
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#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)
 *
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 *	COMPLETE: the most generic way. Device supplied checksum of _all_
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 *	    the packet as seen by netif_rx in skb->csum.
 *	    NOTE: Even if device supports only some protocols, but
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 *	    is able to produce some skb->csum, it MUST use COMPLETE,
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 *	    not UNNECESSARY.
 *
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 *	PARTIAL: identical to the case for output below.  This may occur
 *	    on a packet received directly from another Linux OS, e.g.,
 *	    a virtualised Linux kernel on the same host.  The packet can
 *	    be treated in the same way as UNNECESSARY except that on
 *	    output (i.e., forwarding) the checksum must be filled in
 *	    by the OS or the hardware.
 *
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 * B. Checksumming on output.
 *
 *	NONE: skb is checksummed by protocol or csum is not required.
 *
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 *	PARTIAL: device is required to csum packet as seen by hard_start_xmit
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 *	from skb->csum_start to the end and to record the checksum
 *	at skb->csum_start + skb->csum_offset.
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 *
 *	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)
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 *	NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
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 *
 *	Any questions? No questions, good. 		--ANK
 */

struct net_device;
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struct scatterlist;
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struct pipe_inode_info;
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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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struct nf_conntrack {
	atomic_t use;
};
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#endif
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#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info {
	atomic_t use;
	struct net_device *physindev;
	struct net_device *physoutdev;
	unsigned int mask;
	unsigned long data[32 / sizeof(unsigned long)];
};
#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;
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	__u32 page_offset;
	__u32 size;
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};

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#define HAVE_HW_TIME_STAMP

/**
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 * struct skb_shared_hwtstamps - hardware time stamps
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 * @hwtstamp:	hardware time stamp transformed into duration
 *		since arbitrary point in time
 * @syststamp:	hwtstamp transformed to system time base
 *
 * Software time stamps generated by ktime_get_real() are stored in
 * skb->tstamp. The relation between the different kinds of time
 * stamps is as follows:
 *
 * syststamp and tstamp can be compared against each other in
 * arbitrary combinations.  The accuracy of a
 * syststamp/tstamp/"syststamp from other device" comparison is
 * limited by the accuracy of the transformation into system time
 * base. This depends on the device driver and its underlying
 * hardware.
 *
 * hwtstamps can only be compared against other hwtstamps from
 * the same device.
 *
 * This structure is attached to packets as part of the
 * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
 */
struct skb_shared_hwtstamps {
	ktime_t	hwtstamp;
	ktime_t	syststamp;
};

/**
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 * struct skb_shared_tx - instructions for time stamping of outgoing packets
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 * @hardware:		generate hardware time stamp
 * @software:		generate software time stamp
 * @in_progress:	device driver is going to provide
 *			hardware time stamp
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 * @flags:		all shared_tx flags
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 *
 * These flags are attached to packets as part of the
 * &skb_shared_info. Use skb_tx() to get a pointer.
 */
union skb_shared_tx {
	struct {
		__u8	hardware:1,
			software:1,
			in_progress:1;
	};
	__u8 flags;
};

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/* 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;
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	unsigned short	nr_frags;
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	unsigned short	gso_size;
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#ifdef CONFIG_HAS_DMA
	dma_addr_t	dma_head;
#endif
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	/* Warning: this field is not always filled in (UFO)! */
	unsigned short	gso_segs;
	unsigned short  gso_type;
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	__be32          ip6_frag_id;
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	union skb_shared_tx tx_flags;
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	struct sk_buff	*frag_list;
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	struct skb_shared_hwtstamps hwtstamps;
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	skb_frag_t	frags[MAX_SKB_FRAGS];
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#ifdef CONFIG_HAS_DMA
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	dma_addr_t	dma_maps[MAX_SKB_FRAGS];
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#endif
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	/* Intermediate layers must ensure that destructor_arg
	 * remains valid until skb destructor */
	void *		destructor_arg;
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};

/* 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
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 * the entire skb->data.  A clone of a headerless skb holds the length of
 * the header in skb->hdr_len.
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 *
 * 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)

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enum {
	SKB_FCLONE_UNAVAILABLE,
	SKB_FCLONE_ORIG,
	SKB_FCLONE_CLONE,
};

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enum {
	SKB_GSO_TCPV4 = 1 << 0,
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	SKB_GSO_UDP = 1 << 1,
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	/* This indicates the skb is from an untrusted source. */
	SKB_GSO_DODGY = 1 << 2,
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	/* This indicates the tcp segment has CWR set. */
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	SKB_GSO_TCP_ECN = 1 << 3,

	SKB_GSO_TCPV6 = 1 << 4,
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	SKB_GSO_FCOE = 1 << 5,
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};

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#if BITS_PER_LONG > 32
#define NET_SKBUFF_DATA_USES_OFFSET 1
#endif

#ifdef NET_SKBUFF_DATA_USES_OFFSET
typedef unsigned int sk_buff_data_t;
#else
typedef unsigned char *sk_buff_data_t;
#endif

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/** 
 *	struct sk_buff - socket buffer
 *	@next: Next buffer in list
 *	@prev: Previous buffer in list
 *	@sk: Socket we are owned by
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 *	@tstamp: Time we arrived
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 *	@dev: Device we arrived on/are leaving by
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 *	@transport_header: Transport layer header
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 *	@network_header: Network layer header
 *	@mac_header: Link layer header
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 *	@_skb_dst: destination entry
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 *	@sp: the security path, used for xfrm
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 *	@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
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 *	@hdr_len: writable header length of cloned skb
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 *	@csum: Checksum (must include start/offset pair)
 *	@csum_start: Offset from skb->head where checksumming should start
 *	@csum_offset: Offset from csum_start where checksum should be stored
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 *	@local_df: allow local fragmentation
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 *	@cloned: Head may be cloned (check refcnt to be sure)
 *	@nohdr: Payload reference only, must not modify header
 *	@pkt_type: Packet class
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 *	@fclone: skbuff clone status
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 *	@ip_summed: Driver fed us an IP checksum
 *	@priority: Packet queueing priority
 *	@users: User count - see {datagram,tcp}.c
 *	@protocol: Packet protocol from driver
 *	@truesize: Buffer size 
 *	@head: Head of buffer
 *	@data: Data head pointer
 *	@tail: Tail pointer
 *	@end: End pointer
 *	@destructor: Destruct function
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 *	@mark: Generic packet mark
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 *	@nfct: Associated connection, if any
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 *	@ipvs_property: skbuff is owned by ipvs
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 *	@peeked: this packet has been seen already, so stats have been
 *		done for it, don't do them again
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 *	@nf_trace: netfilter packet trace flag
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 *	@nfctinfo: Relationship of this skb to the connection
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 *	@nfct_reasm: netfilter conntrack re-assembly pointer
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 *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c
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 *	@iif: ifindex of device we arrived on
 *	@queue_mapping: Queue mapping for multiqueue devices
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 *	@tc_index: Traffic control index
 *	@tc_verd: traffic control verdict
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 *	@ndisc_nodetype: router type (from link layer)
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 *	@dma_cookie: a cookie to one of several possible DMA operations
 *		done by skb DMA functions
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 *	@secmark: security marking
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 *	@vlan_tci: vlan tag control information
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 */

struct sk_buff {
	/* These two members must be first. */
	struct sk_buff		*next;
	struct sk_buff		*prev;

	struct sock		*sk;
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	ktime_t			tstamp;
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	struct net_device	*dev;

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	unsigned long		_skb_dst;
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#ifdef CONFIG_XFRM
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	struct	sec_path	*sp;
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#endif
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	/*
	 * 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.
	 */
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	char			cb[48];
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	unsigned int		len,
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				data_len;
	__u16			mac_len,
				hdr_len;
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	union {
		__wsum		csum;
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		struct {
			__u16	csum_start;
			__u16	csum_offset;
		};
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	};
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	__u32			priority;
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	kmemcheck_bitfield_begin(flags1);
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	__u8			local_df:1,
				cloned:1,
				ip_summed:2,
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				nohdr:1,
				nfctinfo:3;
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	__u8			pkt_type:3,
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				fclone:2,
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				ipvs_property:1,
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				peeked:1,
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				nf_trace:1;
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	kmemcheck_bitfield_end(flags1);
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	__be16			protocol;
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	void			(*destructor)(struct sk_buff *skb);
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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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	struct nf_conntrack	*nfct;
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	struct sk_buff		*nfct_reasm;
#endif
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#ifdef CONFIG_BRIDGE_NETFILTER
	struct nf_bridge_info	*nf_bridge;
#endif
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	int			iif;
	__u16			queue_mapping;
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#ifdef CONFIG_NET_SCHED
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	__u16			tc_index;	/* traffic control index */
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#ifdef CONFIG_NET_CLS_ACT
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	__u16			tc_verd;	/* traffic control verdict */
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#endif
#endif
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	kmemcheck_bitfield_begin(flags2);
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#ifdef CONFIG_IPV6_NDISC_NODETYPE
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	__u8			ndisc_nodetype:2;
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#endif
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	kmemcheck_bitfield_end(flags2);

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	/* 0/14 bit hole */
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#ifdef CONFIG_NET_DMA
	dma_cookie_t		dma_cookie;
#endif
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#ifdef CONFIG_NETWORK_SECMARK
	__u32			secmark;
#endif
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	union {
		__u32		mark;
		__u32		dropcount;
	};
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	__u16			vlan_tci;

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	sk_buff_data_t		transport_header;
	sk_buff_data_t		network_header;
	sk_buff_data_t		mac_header;
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	/* These elements must be at the end, see alloc_skb() for details.  */
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	sk_buff_data_t		tail;
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	sk_buff_data_t		end;
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	unsigned char		*head,
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				*data;
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	unsigned int		truesize;
	atomic_t		users;
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};

#ifdef __KERNEL__
/*
 *	Handling routines are only of interest to the kernel
 */
#include <linux/slab.h>

#include <asm/system.h>

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#ifdef CONFIG_HAS_DMA
#include <linux/dma-mapping.h>
extern int skb_dma_map(struct device *dev, struct sk_buff *skb,
		       enum dma_data_direction dir);
extern void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
			  enum dma_data_direction dir);
#endif

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static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
{
	return (struct dst_entry *)skb->_skb_dst;
}

static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
{
	skb->_skb_dst = (unsigned long)dst;
}

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static inline struct rtable *skb_rtable(const struct sk_buff *skb)
{
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	return (struct rtable *)skb_dst(skb);
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}

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extern void kfree_skb(struct sk_buff *skb);
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extern void consume_skb(struct sk_buff *skb);
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extern void	       __kfree_skb(struct sk_buff *skb);
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extern struct sk_buff *__alloc_skb(unsigned int size,
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				   gfp_t priority, int fclone, int node);
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static inline struct sk_buff *alloc_skb(unsigned int size,
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					gfp_t priority)
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{
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	return __alloc_skb(size, priority, 0, -1);
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}

static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
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					       gfp_t priority)
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{
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	return __alloc_skb(size, priority, 1, -1);
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}

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extern int skb_recycle_check(struct sk_buff *skb, int skb_size);

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extern struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
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extern struct sk_buff *skb_clone(struct sk_buff *skb,
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				 gfp_t priority);
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extern struct sk_buff *skb_copy(const struct sk_buff *skb,
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				gfp_t priority);
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extern struct sk_buff *pskb_copy(struct sk_buff *skb,
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				 gfp_t gfp_mask);
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extern int	       pskb_expand_head(struct sk_buff *skb,
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					int nhead, int ntail,
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					gfp_t gfp_mask);
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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,
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				       gfp_t priority);
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extern int	       skb_to_sgvec(struct sk_buff *skb,
				    struct scatterlist *sg, int offset,
				    int len);
extern int	       skb_cow_data(struct sk_buff *skb, int tailbits,
				    struct sk_buff **trailer);
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extern int	       skb_pad(struct sk_buff *skb, int pad);
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#define dev_kfree_skb(a)	consume_skb(a)
#define dev_consume_skb(a)	kfree_skb_clean(a)
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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);

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extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
			int getfrag(void *from, char *to, int offset,
			int len,int odd, struct sk_buff *skb),
			void *from, int length);

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struct skb_seq_state
{
	__u32		lower_offset;
	__u32		upper_offset;
	__u32		frag_idx;
	__u32		stepped_offset;
	struct sk_buff	*root_skb;
	struct sk_buff	*cur_skb;
	__u8		*frag_data;
};

extern void	      skb_prepare_seq_read(struct sk_buff *skb,
					   unsigned int from, unsigned int to,
					   struct skb_seq_state *st);
extern unsigned int   skb_seq_read(unsigned int consumed, const u8 **data,
				   struct skb_seq_state *st);
extern void	      skb_abort_seq_read(struct skb_seq_state *st);

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extern unsigned int   skb_find_text(struct sk_buff *skb, unsigned int from,
				    unsigned int to, struct ts_config *config,
				    struct ts_state *state);

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#ifdef NET_SKBUFF_DATA_USES_OFFSET
static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
{
	return skb->head + skb->end;
}
#else
static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
{
	return skb->end;
}
#endif

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/* Internal */
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#define skb_shinfo(SKB)	((struct skb_shared_info *)(skb_end_pointer(SKB)))
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static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
{
	return &skb_shinfo(skb)->hwtstamps;
}

static inline union skb_shared_tx *skb_tx(struct sk_buff *skb)
{
	return &skb_shinfo(skb)->tx_flags;
}

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/**
 *	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;
}

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/**
 *	skb_queue_is_last - check if skb is the last entry in the queue
 *	@list: queue head
 *	@skb: buffer
 *
 *	Returns true if @skb is the last buffer on the list.
 */
static inline bool skb_queue_is_last(const struct sk_buff_head *list,
				     const struct sk_buff *skb)
{
	return (skb->next == (struct sk_buff *) list);
}

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/**
 *	skb_queue_is_first - check if skb is the first entry in the queue
 *	@list: queue head
 *	@skb: buffer
 *
 *	Returns true if @skb is the first buffer on the list.
 */
static inline bool skb_queue_is_first(const struct sk_buff_head *list,
				      const struct sk_buff *skb)
{
	return (skb->prev == (struct sk_buff *) list);
}

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/**
 *	skb_queue_next - return the next packet in the queue
 *	@list: queue head
 *	@skb: current buffer
 *
 *	Return the next packet in @list after @skb.  It is only valid to
 *	call this if skb_queue_is_last() evaluates to false.
 */
static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
					     const struct sk_buff *skb)
{
	/* This BUG_ON may seem severe, but if we just return then we
	 * are going to dereference garbage.
	 */
	BUG_ON(skb_queue_is_last(list, skb));
	return skb->next;
}

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/**
 *	skb_queue_prev - return the prev packet in the queue
 *	@list: queue head
 *	@skb: current buffer
 *
 *	Return the prev packet in @list before @skb.  It is only valid to
 *	call this if skb_queue_is_first() evaluates to false.
 */
static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
					     const struct sk_buff *skb)
{
	/* This BUG_ON may seem severe, but if we just return then we
	 * are going to dereference garbage.
	 */
	BUG_ON(skb_queue_is_first(list, skb));
	return skb->prev;
}

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/**
 *	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.
 */

/**
 *	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.
 */
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static inline struct sk_buff *skb_share_check(struct sk_buff *skb,
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					      gfp_t pri)
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{
	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.
 */
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static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
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					  gfp_t pri)
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{
	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;
}

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/**
 *	__skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
 *	@list: queue to initialize
 *
 *	This initializes only the list and queue length aspects of
 *	an sk_buff_head object.  This allows to initialize the list
 *	aspects of an sk_buff_head without reinitializing things like
 *	the spinlock.  It can also be used for on-stack sk_buff_head
 *	objects where the spinlock is known to not be used.
 */
static inline void __skb_queue_head_init(struct sk_buff_head *list)
{
	list->prev = list->next = (struct sk_buff *)list;
	list->qlen = 0;
}

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/*
 * This function creates a split out lock class for each invocation;
 * this is needed for now since a whole lot of users of the skb-queue
 * infrastructure in drivers have different locking usage (in hardirq)
 * than the networking core (in softirq only). In the long run either the
 * network layer or drivers should need annotation to consolidate the
 * main types of usage into 3 classes.
 */
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static inline void skb_queue_head_init(struct sk_buff_head *list)
{
	spin_lock_init(&list->lock);
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	__skb_queue_head_init(list);
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}

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static inline void skb_queue_head_init_class(struct sk_buff_head *list,
		struct lock_class_key *class)
{
	skb_queue_head_init(list);
	lockdep_set_class(&list->lock, class);
}

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/*
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 *	Insert an sk_buff on a list.
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 *
 *	The "__skb_xxxx()" functions are the non-atomic ones that
 *	can only be called with interrupts disabled.
 */
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extern void        skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
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;
	list->qlen++;
}
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static inline void __skb_queue_splice(const struct sk_buff_head *list,
				      struct sk_buff *prev,
				      struct sk_buff *next)
{
	struct sk_buff *first = list->next;
	struct sk_buff *last = list->prev;

	first->prev = prev;
	prev->next = first;

	last->next = next;
	next->prev = last;
}

/**
 *	skb_queue_splice - join two skb lists, this is designed for stacks
 *	@list: the new list to add
 *	@head: the place to add it in the first list
 */
static inline void skb_queue_splice(const struct sk_buff_head *list,
				    struct sk_buff_head *head)
{
	if (!skb_queue_empty(list)) {
		__skb_queue_splice(list, (struct sk_buff *) head, head->next);
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		head->qlen += list->qlen;
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	}
}

/**
 *	skb_queue_splice - join two skb lists and reinitialise the emptied list
 *	@list: the new list to add
 *	@head: the place to add it in the first list
 *
 *	The list at @list is reinitialised
 */
static inline void skb_queue_splice_init(struct sk_buff_head *list,
					 struct sk_buff_head *head)
{
	if (!skb_queue_empty(list)) {
		__skb_queue_splice(list, (struct sk_buff *) head, head->next);
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		head->qlen += list->qlen;
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		__skb_queue_head_init(list);
	}
}

/**
 *	skb_queue_splice_tail - join two skb lists, each list being a queue
 *	@list: the new list to add
 *	@head: the place to add it in the first list
 */
static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
					 struct sk_buff_head *head)
{
	if (!skb_queue_empty(list)) {
		__skb_queue_splice(list, head->prev, (struct sk_buff *) head);
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		head->qlen += list->qlen;
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	}
}

/**
 *	skb_queue_splice_tail - join two skb lists and reinitialise the emptied list
 *	@list: the new list to add
 *	@head: the place to add it in the first list
 *
 *	Each of the lists is a queue.
 *	The list at @list is reinitialised
 */
static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
					      struct sk_buff_head *head)
{
	if (!skb_queue_empty(list)) {
		__skb_queue_splice(list, head->prev, (struct sk_buff *) head);
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		head->qlen += list->qlen;
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		__skb_queue_head_init(list);
	}
}

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/**
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 *	__skb_queue_after - queue a buffer at the list head
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 *	@list: list to use
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 *	@prev: place after this buffer
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 *	@newsk: buffer to queue
 *
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 *	Queue a buffer int the middle of a list. This function takes no locks
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 *	and you must therefore hold required locks before calling it.
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
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static inline void __skb_queue_after(struct sk_buff_head *list,
				     struct sk_buff *prev,
				     struct sk_buff *newsk)
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{
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	__skb_insert(newsk, prev, prev->next, list);
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}

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extern void skb_append(struct sk_buff *old, struct sk_buff *newsk,
		       struct sk_buff_head *list);

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static inline void __skb_queue_before(struct sk_buff_head *list,
				      struct sk_buff *next,
				      struct sk_buff *newsk)
{
	__skb_insert(newsk, next->prev, next, list);
}

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/**
 *	__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)
{
	__skb_queue_after(list, (struct sk_buff *)list, newsk);
}

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/**
 *	__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)
{
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	__skb_queue_before(list, (struct sk_buff *)list, newsk);
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}

/*
 * remove sk_buff from list. _Must_ be called atomically, and with
 * the list known..
 */
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extern void	   skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
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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;
	next->prev = prev;
	prev->next = next;
}

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/**
 *	__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 *skb = skb_peek(list);
	if (skb)
		__skb_unlink(skb, list);
	return skb;
}
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/**
 *	__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;
}

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extern void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page,
			    int off, int size);

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#define SKB_PAGE_ASSERT(skb) 	BUG_ON(skb_shinfo(skb)->nr_frags)
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#define SKB_FRAG_ASSERT(skb) 	BUG_ON(skb_has_frags(skb))
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#define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))

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#ifdef NET_SKBUFF_DATA_USES_OFFSET
static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
{
	return skb->head + skb->tail;
}

static inline void skb_reset_tail_pointer(struct sk_buff *skb)
{
	skb->tail = skb->data - skb->head;
}

static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
{
	skb_reset_tail_pointer(skb);
	skb->tail += offset;
}
#else /* NET_SKBUFF_DATA_USES_OFFSET */
static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
{
	return skb->tail;
}

static inline void skb_reset_tail_pointer(struct sk_buff *skb)
{
	skb->tail = skb->data;
}

static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
{
	skb->tail = skb->data + offset;
}
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#endif /* NET_SKBUFF_DATA_USES_OFFSET */

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/*
 *	Add data to an sk_buff
 */
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extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
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static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
{
1124
	unsigned char *tmp = skb_tail_pointer(skb);
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	SKB_LINEAR_ASSERT(skb);
	skb->tail += len;
	skb->len  += len;
	return tmp;
}

1131
extern unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
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static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
{
	skb->data -= len;
	skb->len  += len;
	return skb->data;
}

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extern unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
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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;
}

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) &&
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	    !__pskb_pull_tail(skb, len - skb_headlen(skb)))
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		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;
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	return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
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}

/**
 *	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.
 */
1178
static inline unsigned int skb_headroom(const struct sk_buff *skb)
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{
	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)
{
1191
	return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
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}

/**
 *	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.
 */
1202
static inline void skb_reserve(struct sk_buff *skb, int len)
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{
	skb->data += len;
	skb->tail += len;
}

1208
#ifdef NET_SKBUFF_DATA_USES_OFFSET
1209 1210
static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
{
1211
	return skb->head + skb->transport_header;
1212 1213
}

1214 1215
static inline void skb_reset_transport_header(struct sk_buff *skb)
{
1216
	skb->transport_header = skb->data - skb->head;
1217 1218
}

1219 1220 1221
static inline void skb_set_transport_header(struct sk_buff *skb,
					    const int offset)
{
1222 1223
	skb_reset_transport_header(skb);
	skb->transport_header += offset;
1224 1225
}

1226 1227
static inline unsigned char *skb_network_header(const struct sk_buff *skb)
{
1228
	return skb->head + skb->network_header;
1229 1230
}

1231 1232
static inline void skb_reset_network_header(struct sk_buff *skb)
{
1233
	skb->network_header = skb->data - skb->head;
1234 1235
}

1236 1237
static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
{
1238 1239
	skb_reset_network_header(skb);
	skb->network_header += offset;
1240 1241
}

1242
static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1243
{
1244
	return skb->head + skb->mac_header;
1245 1246
}

1247
static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1248
{
1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293
	return skb->mac_header != ~0U;
}

static inline void skb_reset_mac_header(struct sk_buff *skb)
{
	skb->mac_header = skb->data - skb->head;
}

static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
{
	skb_reset_mac_header(skb);
	skb->mac_header += offset;
}

#else /* NET_SKBUFF_DATA_USES_OFFSET */

static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
{
	return skb->transport_header;
}

static inline void skb_reset_transport_header(struct sk_buff *skb)
{
	skb->transport_header = skb->data;
}

static inline void skb_set_transport_header(struct sk_buff *skb,
					    const int offset)
{
	skb->transport_header = skb->data + offset;
}

static inline unsigned char *skb_network_header(const struct sk_buff *skb)
{
	return skb->network_header;
}

static inline void skb_reset_network_header(struct sk_buff *skb)
{
	skb->network_header = skb->data;
}

static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
{
	skb->network_header = skb->data + offset;
1294 1295
}

1296 1297
static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
{
1298
	return skb->mac_header;
1299 1300 1301 1302
}

static inline int skb_mac_header_was_set(const struct sk_buff *skb)
{
1303
	return skb->mac_header != NULL;
1304 1305
}

1306 1307
static inline void skb_reset_mac_header(struct sk_buff *skb)
{
1308
	skb->mac_header = skb->data;
1309 1310
}

1311 1312
static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
{
1313
	skb->mac_header = skb->data + offset;
1314
}
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#endif /* NET_SKBUFF_DATA_USES_OFFSET */

static inline int skb_transport_offset(const struct sk_buff *skb)
{
	return skb_transport_header(skb) - skb->data;
}

static inline u32 skb_network_header_len(const struct sk_buff *skb)
{
	return skb->transport_header - skb->network_header;
}

static inline int skb_network_offset(const struct sk_buff *skb)
{
	return skb_network_header(skb) - skb->data;
}
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/*
 * 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:
 *
1343
 * skb_reserve(skb, NET_IP_ALIGN);
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 *
 * 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.
1348
 *
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 * 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

1356 1357 1358 1359
/*
 * The networking layer reserves some headroom in skb data (via
 * dev_alloc_skb). This is used to avoid having to reallocate skb data when
 * the header has to grow. In the default case, if the header has to grow
1360
 * 32 bytes or less we avoid the reallocation.
1361 1362 1363 1364 1365 1366 1367
 *
 * Unfortunately this headroom changes the DMA alignment of the resulting
 * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
 * on some architectures. An architecture can override this value,
 * perhaps setting it to a cacheline in size (since that will maintain
 * cacheline alignment of the DMA). It must be a power of 2.
 *
1368
 * Various parts of the networking layer expect at least 32 bytes of
1369 1370 1371
 * headroom, you should not reduce this.
 */
#ifndef NET_SKB_PAD
1372
#define NET_SKB_PAD	32
1373 1374
#endif

1375
extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
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static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
{
1379 1380 1381 1382
	if (unlikely(skb->data_len)) {
		WARN_ON(1);
		return;
	}
1383 1384
	skb->len = len;
	skb_set_tail_pointer(skb, len);
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}

1387
extern void skb_trim(struct sk_buff *skb, unsigned int len);
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static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
{
1391 1392 1393 1394
	if (skb->data_len)
		return ___pskb_trim(skb, len);
	__skb_trim(skb, len);
	return 0;
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}

static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
{
	return (len < skb->len) ? __pskb_trim(skb, len) : 0;
}

1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416
/**
 *	pskb_trim_unique - remove end from a paged unique (not cloned) buffer
 *	@skb: buffer to alter
 *	@len: new length
 *
 *	This is identical to pskb_trim except that the caller knows that
 *	the skb is not cloned so we should never get an error due to out-
 *	of-memory.
 */
static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
{
	int err = pskb_trim(skb, len);
	BUG_ON(err);
}

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/**
 *	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);
}

/**
1450
 *	__dev_alloc_skb - allocate an skbuff for receiving
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 *	@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.
 *
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 *	%NULL is returned if there is no free memory.
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 */
static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
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					      gfp_t gfp_mask)
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{
1464
	struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
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	if (likely(skb))
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		skb_reserve(skb, NET_SKB_PAD);
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	return skb;
}

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extern struct sk_buff *dev_alloc_skb(unsigned int length);
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extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
		unsigned int length, gfp_t gfp_mask);

/**
 *	netdev_alloc_skb - allocate an skbuff for rx on a specific device
 *	@dev: network device to receive on
 *	@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.
 */
static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
		unsigned int length)
{
	return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
}

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extern struct page *__netdev_alloc_page(struct net_device *dev, gfp_t gfp_mask);

/**
 *	netdev_alloc_page - allocate a page for ps-rx on a specific device
 *	@dev: network device to receive on
 *
 * 	Allocate a new page node local to the specified device.
 *
 * 	%NULL is returned if there is no free memory.
 */
static inline struct page *netdev_alloc_page(struct net_device *dev)
{
	return __netdev_alloc_page(dev, GFP_ATOMIC);
}

static inline void netdev_free_page(struct net_device *dev, struct page *page)
{
	__free_page(page);
}

1514 1515 1516 1517 1518 1519 1520 1521
/**
 *	skb_clone_writable - is the header of a clone writable
 *	@skb: buffer to check
 *	@len: length up to which to write
 *
 *	Returns true if modifying the header part of the cloned buffer
 *	does not requires the data to be copied.
 */
1522
static inline int skb_clone_writable(struct sk_buff *skb, unsigned int len)
1523 1524 1525 1526 1527
{
	return !skb_header_cloned(skb) &&
	       skb_headroom(skb) + len <= skb->hdr_len;
}

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static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
			    int cloned)
{
	int delta = 0;

	if (headroom < NET_SKB_PAD)
		headroom = NET_SKB_PAD;
	if (headroom > skb_headroom(skb))
		delta = headroom - skb_headroom(skb);

	if (delta || cloned)
		return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
					GFP_ATOMIC);
	return 0;
}

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/**
 *	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)
{
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	return __skb_cow(skb, headroom, skb_cloned(skb));
}
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/**
 *	skb_cow_head - skb_cow but only making the head writable
 *	@skb: buffer to cow
 *	@headroom: needed headroom
 *
 *	This function is identical to skb_cow except that we replace the
 *	skb_cloned check by skb_header_cloned.  It should be used when
 *	you only need to push on some header and do not need to modify
 *	the data.
 */
static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
{
	return __skb_cow(skb, headroom, skb_header_cloned(skb));
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}

/**
 *	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
1583 1584
 *	is untouched. Otherwise it is extended. Returns zero on
 *	success. The skb is freed on error.
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 */
 
1587
static inline int skb_padto(struct sk_buff *skb, unsigned int len)
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{
	unsigned int size = skb->len;
	if (likely(size >= len))
1591
		return 0;
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	return skb_pad(skb, len - size);
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}

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;
1602
		__wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
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							    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;
}

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static inline int __skb_linearize(struct sk_buff *skb)
{
	return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
}

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/**
 *	skb_linearize - convert paged skb to linear one
 *	@skb: buffer to linarize
 *
 *	If there is no free memory -ENOMEM is returned, otherwise zero
 *	is returned and the old skb data released.
 */
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static inline int skb_linearize(struct sk_buff *skb)
{
	return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
}

/**
 *	skb_linearize_cow - make sure skb is linear and writable
 *	@skb: buffer to process
 *
 *	If there is no free memory -ENOMEM is returned, otherwise zero
 *	is returned and the old skb data released.
 */
static inline int skb_linearize_cow(struct sk_buff *skb)
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{
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	return skb_is_nonlinear(skb) || skb_cloned(skb) ?
	       __skb_linearize(skb) : 0;
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}

/**
 *	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
1664 1665
 *	update the CHECKSUM_COMPLETE checksum, or set ip_summed to
 *	CHECKSUM_NONE so that it can be recomputed from scratch.
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 */

static inline void skb_postpull_rcsum(struct sk_buff *skb,
1669
				      const void *start, unsigned int len)
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{
1671
	if (skb->ip_summed == CHECKSUM_COMPLETE)
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		skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
}

1675 1676
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);

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/**
 *	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)
{
1688
	if (likely(len >= skb->len))
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		return 0;
1690
	if (skb->ip_summed == CHECKSUM_COMPLETE)
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		skb->ip_summed = CHECKSUM_NONE;
	return __pskb_trim(skb, len);
}

#define skb_queue_walk(queue, skb) \
		for (skb = (queue)->next;					\
		     prefetch(skb->next), (skb != (struct sk_buff *)(queue));	\
		     skb = skb->next)

1700 1701 1702 1703 1704
#define skb_queue_walk_safe(queue, skb, tmp)					\
		for (skb = (queue)->next, tmp = skb->next;			\
		     skb != (struct sk_buff *)(queue);				\
		     skb = tmp, tmp = skb->next)

1705 1706 1707 1708 1709 1710 1711 1712 1713
#define skb_queue_walk_from(queue, skb)						\
		for (; prefetch(skb->next), (skb != (struct sk_buff *)(queue));	\
		     skb = skb->next)

#define skb_queue_walk_from_safe(queue, skb, tmp)				\
		for (tmp = skb->next;						\
		     skb != (struct sk_buff *)(queue);				\
		     skb = tmp, tmp = skb->next)

1714 1715 1716 1717 1718
#define skb_queue_reverse_walk(queue, skb) \
		for (skb = (queue)->prev;					\
		     prefetch(skb->prev), (skb != (struct sk_buff *)(queue));	\
		     skb = skb->prev)

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1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738
static inline bool skb_has_frags(const struct sk_buff *skb)
{
	return skb_shinfo(skb)->frag_list != NULL;
}

static inline void skb_frag_list_init(struct sk_buff *skb)
{
	skb_shinfo(skb)->frag_list = NULL;
}

static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
{
	frag->next = skb_shinfo(skb)->frag_list;
	skb_shinfo(skb)->frag_list = frag;
}

#define skb_walk_frags(skb, iter)	\
	for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)

1739 1740
extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
					   int *peeked, int *err);
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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);
1748
extern int	       skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
L
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							int hlen,
							struct iovec *iov);
1751 1752
extern int	       skb_copy_datagram_from_iovec(struct sk_buff *skb,
						    int offset,
1753 1754
						    const struct iovec *from,
						    int from_offset,
1755
						    int len);
1756 1757 1758 1759 1760
extern int	       skb_copy_datagram_const_iovec(const struct sk_buff *from,
						     int offset,
						     const struct iovec *to,
						     int to_offset,
						     int size);
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extern void	       skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1762
extern int	       skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
1763
					 unsigned int flags);
1764 1765
extern __wsum	       skb_checksum(const struct sk_buff *skb, int offset,
				    int len, __wsum csum);
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extern int	       skb_copy_bits(const struct sk_buff *skb, int offset,
				     void *to, int len);
1768 1769
extern int	       skb_store_bits(struct sk_buff *skb, int offset,
				      const void *from, int len);
1770
extern __wsum	       skb_copy_and_csum_bits(const struct sk_buff *skb,
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					      int offset, u8 *to, int len,
1772
					      __wsum csum);
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extern int             skb_splice_bits(struct sk_buff *skb,
						unsigned int offset,
						struct pipe_inode_info *pipe,
						unsigned int len,
						unsigned int flags);
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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);
1781 1782
extern int	       skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
				 int shiftlen);
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1784
extern struct sk_buff *skb_segment(struct sk_buff *skb, int features);
1785

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static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
				       int len, void *buffer)
{
	int hlen = skb_headlen(skb);

1791
	if (hlen - offset >= len)
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		return skb->data + offset;

	if (skb_copy_bits(skb, offset, buffer, len) < 0)
		return NULL;

	return buffer;
}

1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813
static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
					     void *to,
					     const unsigned int len)
{
	memcpy(to, skb->data, len);
}

static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
						    const int offset, void *to,
						    const unsigned int len)
{
	memcpy(to, skb->data + offset, len);
}

1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828
static inline void skb_copy_to_linear_data(struct sk_buff *skb,
					   const void *from,
					   const unsigned int len)
{
	memcpy(skb->data, from, len);
}

static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
						  const int offset,
						  const void *from,
						  const unsigned int len)
{
	memcpy(skb->data + offset, from, len);
}

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extern void skb_init(void);

1831 1832 1833 1834 1835
static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
{
	return skb->tstamp;
}

1836 1837 1838 1839 1840 1841 1842 1843 1844
/**
 *	skb_get_timestamp - get timestamp from a skb
 *	@skb: skb to get stamp from
 *	@stamp: pointer to struct timeval to store stamp in
 *
 *	Timestamps are stored in the skb as offsets to a base timestamp.
 *	This function converts the offset back to a struct timeval and stores
 *	it in stamp.
 */
1845 1846
static inline void skb_get_timestamp(const struct sk_buff *skb,
				     struct timeval *stamp)
1847
{
1848
	*stamp = ktime_to_timeval(skb->tstamp);
1849 1850
}

1851 1852 1853 1854 1855 1856
static inline void skb_get_timestampns(const struct sk_buff *skb,
				       struct timespec *stamp)
{
	*stamp = ktime_to_timespec(skb->tstamp);
}

1857
static inline void __net_timestamp(struct sk_buff *skb)
1858
{
1859
	skb->tstamp = ktime_get_real();
1860 1861
}

1862 1863 1864 1865 1866
static inline ktime_t net_timedelta(ktime_t t)
{
	return ktime_sub(ktime_get_real(), t);
}

1867 1868 1869 1870
static inline ktime_t net_invalid_timestamp(void)
{
	return ktime_set(0, 0);
}
1871

1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885
/**
 * skb_tstamp_tx - queue clone of skb with send time stamps
 * @orig_skb:	the original outgoing packet
 * @hwtstamps:	hardware time stamps, may be NULL if not available
 *
 * If the skb has a socket associated, then this function clones the
 * skb (thus sharing the actual data and optional structures), stores
 * the optional hardware time stamping information (if non NULL) or
 * generates a software time stamp (otherwise), then queues the clone
 * to the error queue of the socket.  Errors are silently ignored.
 */
extern void skb_tstamp_tx(struct sk_buff *orig_skb,
			struct skb_shared_hwtstamps *hwtstamps);

1886
extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
1887
extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
1888

1889 1890 1891 1892 1893
static inline int skb_csum_unnecessary(const struct sk_buff *skb)
{
	return skb->ip_summed & CHECKSUM_UNNECESSARY;
}

1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909
/**
 *	skb_checksum_complete - Calculate checksum of an entire packet
 *	@skb: packet to process
 *
 *	This function calculates the checksum over the entire packet plus
 *	the value of skb->csum.  The latter can be used to supply the
 *	checksum of a pseudo header as used by TCP/UDP.  It returns the
 *	checksum.
 *
 *	For protocols that contain complete checksums such as ICMP/TCP/UDP,
 *	this function can be used to verify that checksum on received
 *	packets.  In that case the function should return zero if the
 *	checksum is correct.  In particular, this function will return zero
 *	if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
 *	hardware has already verified the correctness of the checksum.
 */
1910
static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
1911
{
1912 1913
	return skb_csum_unnecessary(skb) ?
	       0 : __skb_checksum_complete(skb);
1914 1915
}

1916
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1917
extern void nf_conntrack_destroy(struct nf_conntrack *nfct);
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static inline void nf_conntrack_put(struct nf_conntrack *nfct)
{
	if (nfct && atomic_dec_and_test(&nfct->use))
1921
		nf_conntrack_destroy(nfct);
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}
static inline void nf_conntrack_get(struct nf_conntrack *nfct)
{
	if (nfct)
		atomic_inc(&nfct->use);
}
1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938
static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
{
	if (skb)
		atomic_inc(&skb->users);
}
static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
{
	if (skb)
		kfree_skb(skb);
}
#endif
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#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 */
1951 1952
static inline void nf_reset(struct sk_buff *skb)
{
1953
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964
	nf_conntrack_put(skb->nfct);
	skb->nfct = NULL;
	nf_conntrack_put_reasm(skb->nfct_reasm);
	skb->nfct_reasm = NULL;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
	nf_bridge_put(skb->nf_bridge);
	skb->nf_bridge = NULL;
#endif
}

1965 1966 1967
/* Note: This doesn't put any conntrack and bridge info in dst. */
static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
{
1968
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980
	dst->nfct = src->nfct;
	nf_conntrack_get(src->nfct);
	dst->nfctinfo = src->nfctinfo;
	dst->nfct_reasm = src->nfct_reasm;
	nf_conntrack_get_reasm(src->nfct_reasm);
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
	dst->nf_bridge  = src->nf_bridge;
	nf_bridge_get(src->nf_bridge);
#endif
}

1981 1982 1983
static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
{
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1984
	nf_conntrack_put(dst->nfct);
1985 1986 1987 1988 1989 1990 1991 1992
	nf_conntrack_put_reasm(dst->nfct_reasm);
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
	nf_bridge_put(dst->nf_bridge);
#endif
	__nf_copy(dst, src);
}

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
#ifdef CONFIG_NETWORK_SECMARK
static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
{
	to->secmark = from->secmark;
}

static inline void skb_init_secmark(struct sk_buff *skb)
{
	skb->secmark = 0;
}
#else
static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
{ }

static inline void skb_init_secmark(struct sk_buff *skb)
{ }
#endif

2011 2012 2013 2014 2015
static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
{
	skb->queue_mapping = queue_mapping;
}

2016
static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
2017 2018 2019 2020
{
	return skb->queue_mapping;
}

2021 2022 2023 2024 2025
static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
{
	to->queue_mapping = from->queue_mapping;
}

2026 2027 2028 2029 2030
static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
{
	skb->queue_mapping = rx_queue + 1;
}

2031
static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
2032 2033 2034 2035
{
	return skb->queue_mapping - 1;
}

2036
static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
2037 2038 2039 2040
{
	return (skb->queue_mapping != 0);
}

2041 2042 2043
extern u16 skb_tx_hash(const struct net_device *dev,
		       const struct sk_buff *skb);

2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055
#ifdef CONFIG_XFRM
static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
{
	return skb->sp;
}
#else
static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
{
	return NULL;
}
#endif

H
Herbert Xu 已提交
2056 2057 2058 2059 2060
static inline int skb_is_gso(const struct sk_buff *skb)
{
	return skb_shinfo(skb)->gso_size;
}

B
Brice Goglin 已提交
2061 2062 2063 2064 2065
static inline int skb_is_gso_v6(const struct sk_buff *skb)
{
	return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
}

2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079
extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);

static inline bool skb_warn_if_lro(const struct sk_buff *skb)
{
	/* LRO sets gso_size but not gso_type, whereas if GSO is really
	 * wanted then gso_type will be set. */
	struct skb_shared_info *shinfo = skb_shinfo(skb);
	if (shinfo->gso_size != 0 && unlikely(shinfo->gso_type == 0)) {
		__skb_warn_lro_forwarding(skb);
		return true;
	}
	return false;
}

2080 2081 2082 2083 2084 2085 2086
static inline void skb_forward_csum(struct sk_buff *skb)
{
	/* Unfortunately we don't support this one.  Any brave souls? */
	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->ip_summed = CHECKSUM_NONE;
}

2087
bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
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#endif	/* __KERNEL__ */
#endif	/* _LINUX_SKBUFF_H */