1. 根目录:
2. net
3. atm
4. raw.c

/* net/atm/raw.c - Raw AAL0 and AAL5 transports */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/module.h>
#include <linux/atmdev.h>
#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include "common.h"
#include "protocols.h"

/*
 * SKB == NULL indicates that the link is being closed
 */

static void atm_push_raw(struct atm_vcc *vcc, struct sk_buff *skb)
{
	if (skb) {
		struct sock *sk = sk_atm(vcc);

		skb_queue_tail(&sk->sk_receive_queue, skb);
		sk->sk_data_ready(sk, skb->len);
	}
}

static void atm_pop_raw(struct atm_vcc *vcc, struct sk_buff *skb)
{
	struct sock *sk = sk_atm(vcc);

	pr_debug("(%d) %d -= %d\n",
		 vcc->vci, sk_wmem_alloc_get(sk), skb->truesize);
	atomic_sub(skb->truesize, &sk->sk_wmem_alloc);
	dev_kfree_skb_any(skb);
	sk->sk_write_space(sk);
}

static int atm_send_aal0(struct atm_vcc *vcc, struct sk_buff *skb)
{
	/*
	 * Note that if vpi/vci are _ANY or _UNSPEC the below will
	 * still work
	 */
	if (!capable(CAP_NET_ADMIN) &&
	    (((u32 *)skb->data)[0] & (ATM_HDR_VPI_MASK | ATM_HDR_VCI_MASK)) !=
	    ((vcc->vpi << ATM_HDR_VPI_SHIFT) |
	     (vcc->vci << ATM_HDR_VCI_SHIFT))) {
		kfree_skb(skb);
		return -EADDRNOTAVAIL;
	}
	return vcc->dev->ops->send(vcc, skb);
}

int atm_init_aal0(struct atm_vcc *vcc)
{
	vcc->push = atm_push_raw;
	vcc->pop = atm_pop_raw;
	vcc->push_oam = NULL;
	vcc->send = atm_send_aal0;
	return 0;
}

int atm_init_aal34(struct atm_vcc *vcc)
{
	vcc->push = atm_push_raw;
	vcc->pop = atm_pop_raw;
	vcc->push_oam = NULL;
	vcc->send = vcc->dev->ops->send;
	return 0;
}

int atm_init_aal5(struct atm_vcc *vcc)
{
	vcc->push = atm_push_raw;
	vcc->pop = atm_pop_raw;
	vcc->push_oam = NULL;
	vcc->send = vcc->dev->ops->send;
	return 0;
}
EXPORT_SYMBOL(atm_init_aal5);