skbuff.c

GNU Hurd 源代码

/*
 *	Routines having to do with the 'struct sk_buff' memory handlers.
 *
 *	Authors:	Alan Cox <[e-mail]>
 *			Florian La Roche <[e-mail]>
 *
 *	Version:	$Id: skbuff.c,v 1.55 1999/02/23 08:12:27 davem Exp $
 *
 *	Fixes:	
 *		Alan Cox	:	Fixed the worst of the load balancer bugs.
 *		Dave Platt	:	Interrupt stacking fix.
 *	Richard Kooijman	:	Timestamp fixes.
 *		Alan Cox	:	Changed buffer format.
 *		Alan Cox	:	destructor hook for AF_UNIX etc.
 *		Linus Torvalds	:	Better skb_clone.
 *		Alan Cox	:	Added skb_copy.
 *		Alan Cox	:	Added all the changed routines Linus
 *					only put in the headers
 *		Ray VanTassle	:	Fixed --skb->lock in free
 *		Alan Cox	:	skb_copy copy arp field
 *		Andi Kleen	:	slabified it.
 *
 *	NOTE:
 *		The __skb_ routines should be called with interrupts 
 *	disabled, or you better be *real* sure that the operation is atomic 
 *	with respect to whatever list is being frobbed (e.g. via lock_sock()
 *	or via disabling bottom half handlers, etc).
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

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

#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/malloc.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/init.h>

#include <net/ip.h>
#include <net/protocol.h>
#include <net/dst.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/sock.h>

#include <asm/uaccess.h>
#include <asm/system.h>

/*
 * Skb list spinlock
 */
spinlock_t skb_queue_lock = SPIN_LOCK_UNLOCKED;

/*
 *	Resource tracking variables
 */

static atomic_t net_skbcount = ATOMIC_INIT(0);
static atomic_t net_allocs = ATOMIC_INIT(0);
static atomic_t net_fails  = ATOMIC_INIT(0);

extern atomic_t ip_frag_mem;

static kmem_cache_t *skbuff_head_cache;

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

void skb_over_panic(struct sk_buff *skb, int sz, void *here)
{
	panic("skput:over: %p:%d put:%d dev:%s", 
		here, skb->len, sz, skb->dev ? skb->dev->name : "<NULL>");
}

void skb_under_panic(struct sk_buff *skb, int sz, void *here)
{
        panic("skput:under: %p:%d put:%d dev:%s",
                here, skb->len, sz, skb->dev ? skb->dev->name : "<NULL>");
}

void show_net_buffers(void)
{
	printk("Networking buffers in use          : %u\n",
	       atomic_read(&net_skbcount));
	printk("Total network buffer allocations   : %u\n",
	       atomic_read(&net_allocs));
	printk("Total failed network buffer allocs : %u\n",
	       atomic_read(&net_fails));
#ifdef CONFIG_INET
	printk("IP fragment buffer size            : %u\n",
	       atomic_read(&ip_frag_mem));
#endif	
}

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

struct sk_buff *alloc_skb(unsigned int size,int gfp_mask)
{
	struct sk_buff *skb;
	u8 *data;

	if (in_interrupt() && (gfp_mask & __GFP_WAIT)) {
		static int count = 0;
		if (++count < 5) {
			printk(KERN_ERR "alloc_skb called nonatomically "
			       "from interrupt %p\n", __builtin_return_address(0));
		}
		gfp_mask &= ~__GFP_WAIT;
	}

	/* Get the HEAD */
	skb = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
	if (skb == NULL) 
		goto nohead;

	/* Get the DATA. Size must match skb_add_mtu(). */
	size = ((size + 15) & ~15); 
	data = kmalloc(size + sizeof(atomic_t), gfp_mask);
	if (data == NULL)
		goto nodata;

	/* Note that this counter is useless now - you can just look in the
	 * skbuff_head entry in /proc/slabinfo. We keep it only for emergency
	 * cases.
	 */
	atomic_inc(&net_allocs);

	skb->truesize = size;

	atomic_inc(&net_skbcount);

	/* Load the data pointers. */
	skb->head = data;
	skb->data = data;
	skb->tail = data;
	skb->end = data + size;

	/* Set up other state */
	skb->len = 0;
	skb->is_clone = 0;
	skb->cloned = 0;

	atomic_set(&skb->users, 1); 
	atomic_set(skb_datarefp(skb), 1);
	return skb;

nodata:
	kmem_cache_free(skbuff_head_cache, skb);
nohead:
	atomic_inc(&net_fails);
	return NULL;
}


/*
 *	Slab constructor for a skb head. 
 */ 
static inline void skb_headerinit(void *p, kmem_cache_t *cache, 
				  unsigned long flags)
{
	struct sk_buff *skb = p;

	skb->destructor = NULL;
	skb->pkt_type = PACKET_HOST;	/* Default type */
	skb->pkt_bridged = 0;		/* Not bridged */
	skb->prev = skb->next = NULL;
	skb->list = NULL;
	skb->sk = NULL;
	skb->stamp.tv_sec=0;	/* No idea about time */
	skb->ip_summed = 0;
	skb->security = 0;	/* By default packets are insecure */
	skb->dst = NULL;
#ifdef CONFIG_IP_FIREWALL
        skb->fwmark = 0;
#endif
	memset(skb->cb, 0, sizeof(skb->cb));
	skb->priority = 0;
}

/*
 *	Free an skbuff by memory without cleaning the state. 
 */
void kfree_skbmem(struct sk_buff *skb)
{
	if (!skb->cloned || atomic_dec_and_test(skb_datarefp(skb)))  
		kfree(skb->head);

	kmem_cache_free(skbuff_head_cache, skb);
	atomic_dec(&net_skbcount);
}

/*
 *	Free an sk_buff. Release anything attached to the buffer. Clean the state.
 */

void __kfree_skb(struct sk_buff *skb)
{
	if (skb->list)
	 	printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
		       "on a list (from %p).\n", __builtin_return_address(0));

	dst_release(skb->dst);
	if(skb->destructor)
		skb->destructor(skb);
	skb_headerinit(skb, NULL, 0);  /* clean state */
	kfree_skbmem(skb);
}

/*
 *	Duplicate an sk_buff. The new one is not owned by a socket.
 */

struct sk_buff *skb_clone(struct sk_buff *skb, int gfp_mask)
{
	struct sk_buff *n;
	
	n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
	if (!n)
		return NULL;

	memcpy(n, skb, sizeof(*n));
	atomic_inc(skb_datarefp(skb));
	skb->cloned = 1;
       
	atomic_inc(&net_allocs);
	atomic_inc(&net_skbcount);
	dst_clone(n->dst);
	n->cloned = 1;
	n->next = n->prev = NULL;
	n->list = NULL;
	n->sk = NULL;
	n->is_clone = 1;
	atomic_set(&n->users, 1);
	n->destructor = NULL;
	return n;
}

/*
 *	This is slower, and copies the whole data area 
 */
 
struct sk_buff *skb_copy(struct sk_buff *skb, int gfp_mask)
{
	struct sk_buff *n;
	unsigned long offset;

	/*
	 *	Allocate the copy buffer
	 */
	 
	n=alloc_skb(skb->end - skb->head, gfp_mask);
	if(n==NULL)
		return NULL;

	/*
	 *	Shift between the two data areas in bytes
	 */
	 
	offset=n->head-skb->head;

	/* Set the data pointer */
	skb_reserve(n,skb->data-skb->head);
	/* Set the tail pointer and length */
	skb_put(n,skb->len);
	/* Copy the bytes */
	memcpy(n->head,skb->head,skb->end-skb->head);
	n->csum = skb->csum;
	n->list=NULL;
	n->sk=NULL;
	n->dev=skb->dev;
	n->priority=skb->priority;
	n->protocol=skb->protocol;
	n->dst=dst_clone(skb->dst);
	n->h.raw=skb->h.raw+offset;
	n->nh.raw=skb->nh.raw+offset;
	n->mac.raw=skb->mac.raw+offset;
	memcpy(n->cb, skb->cb, sizeof(skb->cb));
	n->used=skb->used;
	n->is_clone=0;
	atomic_set(&n->users, 1);
	n->pkt_type=skb->pkt_type;
	n->stamp=skb->stamp;
	n->destructor = NULL;
	n->security=skb->security;
#ifdef CONFIG_IP_FIREWALL
        n->fwmark = skb->fwmark;
#endif
	return n;
}

struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, int newheadroom)
{
	struct sk_buff *n;
	unsigned long offset;
	int headroom = skb_headroom(skb);

	/*
	 *	Allocate the copy buffer
	 */
 	 
	n=alloc_skb(skb->truesize+newheadroom-headroom, GFP_ATOMIC);
	if(n==NULL)
		return NULL;

	skb_reserve(n,newheadroom);

	/*
	 *	Shift between the two data areas in bytes
	 */
	 
	offset=n->data-skb->data;

	/* Set the tail pointer and length */
	skb_put(n,skb->len);
	/* Copy the bytes */
	memcpy(n->data,skb->data,skb->len);
	n->list=NULL;
	n->sk=NULL;
	n->priority=skb->priority;
	n->protocol=skb->protocol;
	n->dev=skb->dev;
	n->dst=dst_clone(skb->dst);
	n->h.raw=skb->h.raw+offset;
	n->nh.raw=skb->nh.raw+offset;
	n->mac.raw=skb->mac.raw+offset;
	memcpy(n->cb, skb->cb, sizeof(skb->cb));
	n->used=skb->used;
	n->is_clone=0;
	atomic_set(&n->users, 1);
	n->pkt_type=skb->pkt_type;
	n->stamp=skb->stamp;
	n->destructor = NULL;
	n->security=skb->security;
#ifdef CONFIG_IP_FIREWALL
        n->fwmark = skb->fwmark;
#endif

	return n;
}

#if 0
/* 
 * 	Tune the memory allocator for a new MTU size.
 */
void skb_add_mtu(int mtu)
{
	/* Must match allocation in alloc_skb */
	mtu = ((mtu + 15) & ~15) + sizeof(atomic_t);

	kmem_add_cache_size(mtu);
}
#endif

void __init skb_init(void)
{
	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
					      sizeof(struct sk_buff),
					      0,
					      SLAB_HWCACHE_ALIGN,
					      skb_headerinit, NULL);
	if (!skbuff_head_cache)
		panic("cannot create skbuff cache");
}