diff options
Diffstat (limited to 'release/src/linux/linux/net/ipv4/igmp.c')
| -rw-r--r-- | release/src/linux/linux/net/ipv4/igmp.c | 833 |
1 files changed, 833 insertions, 0 deletions
diff --git a/release/src/linux/linux/net/ipv4/igmp.c b/release/src/linux/linux/net/ipv4/igmp.c new file mode 100644 index 00000000..3f718f2a --- /dev/null +++ b/release/src/linux/linux/net/ipv4/igmp.c @@ -0,0 +1,833 @@ +/* + * Linux NET3: Internet Group Management Protocol [IGMP] + * + * This code implements the IGMP protocol as defined in RFC1112. There has + * been a further revision of this protocol since which is now supported. + * + * If you have trouble with this module be careful what gcc you have used, + * the older version didn't come out right using gcc 2.5.8, the newer one + * seems to fall out with gcc 2.6.2. + * + * Version: $Id: igmp.c,v 1.1.1.4 2003/10/14 08:09:33 sparq Exp $ + * + * Authors: + * Alan Cox <Alan.Cox@linux.org> + * + * 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. + * + * Fixes: + * + * Alan Cox : Added lots of __inline__ to optimise + * the memory usage of all the tiny little + * functions. + * Alan Cox : Dumped the header building experiment. + * Alan Cox : Minor tweaks ready for multicast routing + * and extended IGMP protocol. + * Alan Cox : Removed a load of inline directives. Gcc 2.5.8 + * writes utterly bogus code otherwise (sigh) + * fixed IGMP loopback to behave in the manner + * desired by mrouted, fixed the fact it has been + * broken since 1.3.6 and cleaned up a few minor + * points. + * + * Chih-Jen Chang : Tried to revise IGMP to Version 2 + * Tsu-Sheng Tsao E-mail: chihjenc@scf.usc.edu and tsusheng@scf.usc.edu + * The enhancements are mainly based on Steve Deering's + * ipmulti-3.5 source code. + * Chih-Jen Chang : Added the igmp_get_mrouter_info and + * Tsu-Sheng Tsao igmp_set_mrouter_info to keep track of + * the mrouted version on that device. + * Chih-Jen Chang : Added the max_resp_time parameter to + * Tsu-Sheng Tsao igmp_heard_query(). Using this parameter + * to identify the multicast router version + * and do what the IGMP version 2 specified. + * Chih-Jen Chang : Added a timer to revert to IGMP V2 router + * Tsu-Sheng Tsao if the specified time expired. + * Alan Cox : Stop IGMP from 0.0.0.0 being accepted. + * Alan Cox : Use GFP_ATOMIC in the right places. + * Christian Daudt : igmp timer wasn't set for local group + * memberships but was being deleted, + * which caused a "del_timer() called + * from %p with timer not initialized\n" + * message (960131). + * Christian Daudt : removed del_timer from + * igmp_timer_expire function (960205). + * Christian Daudt : igmp_heard_report now only calls + * igmp_timer_expire if tm->running is + * true (960216). + * Malcolm Beattie : ttl comparison wrong in igmp_rcv made + * igmp_heard_query never trigger. Expiry + * miscalculation fixed in igmp_heard_query + * and random() made to return unsigned to + * prevent negative expiry times. + * Alexey Kuznetsov: Wrong group leaving behaviour, backport + * fix from pending 2.1.x patches. + * Alan Cox: Forget to enable FDDI support earlier. + * Alexey Kuznetsov: Fixed leaving groups on device down. + * Alexey Kuznetsov: Accordance to igmp-v2-06 draft. + */ + + +#include <linux/config.h> +#include <asm/uaccess.h> +#include <asm/system.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/string.h> +#include <linux/socket.h> +#include <linux/sockios.h> +#include <linux/in.h> +#include <linux/inet.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/inetdevice.h> +#include <linux/igmp.h> +#include <linux/if_arp.h> +#include <linux/rtnetlink.h> +#include <net/ip.h> +#include <net/protocol.h> +#include <net/route.h> +#include <net/sock.h> +#include <net/checksum.h> +#include <linux/netfilter_ipv4.h> +#ifdef CONFIG_IP_MROUTE +#include <linux/mroute.h> +#endif + + +#define IP_MAX_MEMBERSHIPS 20 + +#ifdef CONFIG_IP_MULTICAST + + +/* Parameter names and values are taken from igmp-v2-06 draft */ + +#define IGMP_V1_Router_Present_Timeout (400*HZ) +#define IGMP_Unsolicited_Report_Interval (10*HZ) +#define IGMP_Query_Response_Interval (10*HZ) +#define IGMP_Unsolicited_Report_Count 2 + + +#define IGMP_Initial_Report_Delay (1) + +/* IGMP_Initial_Report_Delay is not from IGMP specs! + * IGMP specs require to report membership immediately after + * joining a group, but we delay the first report by a + * small interval. It seems more natural and still does not + * contradict to specs provided this delay is small enough. + */ + +#define IGMP_V1_SEEN(in_dev) ((in_dev)->mr_v1_seen && (long)(jiffies - (in_dev)->mr_v1_seen) < 0) + +#endif + +static void ip_ma_put(struct ip_mc_list *im) +{ + if (atomic_dec_and_test(&im->refcnt)) { + in_dev_put(im->interface); + kfree(im); + } +} + +#ifdef CONFIG_IP_MULTICAST + +/* + * Timer management + */ + +static __inline__ void igmp_stop_timer(struct ip_mc_list *im) +{ + spin_lock_bh(&im->lock); + if (del_timer(&im->timer)) + atomic_dec(&im->refcnt); + im->tm_running=0; + im->reporter = 0; + im->unsolicit_count = 0; + spin_unlock_bh(&im->lock); +} + +/* It must be called with locked im->lock */ +static void igmp_start_timer(struct ip_mc_list *im, int max_delay) +{ + int tv=net_random() % max_delay; + + im->tm_running=1; + if (!mod_timer(&im->timer, jiffies+tv+2)) + atomic_inc(&im->refcnt); +} + +static void igmp_mod_timer(struct ip_mc_list *im, int max_delay) +{ + spin_lock_bh(&im->lock); + im->unsolicit_count = 0; + if (del_timer(&im->timer)) { + if ((long)(im->timer.expires-jiffies) < max_delay) { + add_timer(&im->timer); + im->tm_running=1; + spin_unlock_bh(&im->lock); + return; + } + atomic_dec(&im->refcnt); + } + igmp_start_timer(im, max_delay); + spin_unlock_bh(&im->lock); +} + + +/* + * Send an IGMP report. + */ + +#define IGMP_SIZE (sizeof(struct igmphdr)+sizeof(struct iphdr)+4) + +/* Don't just hand NF_HOOK skb->dst->output, in case netfilter hook + changes route */ +static inline int +output_maybe_reroute(struct sk_buff *skb) +{ + return skb->dst->output(skb); +} + +static int igmp_send_report(struct net_device *dev, u32 group, int type) +{ + struct sk_buff *skb; + struct iphdr *iph; + struct igmphdr *ih; + struct rtable *rt; + u32 dst; + + /* According to IGMPv2 specs, LEAVE messages are + * sent to all-routers group. + */ + dst = group; + if (type == IGMP_HOST_LEAVE_MESSAGE) + dst = IGMP_ALL_ROUTER; + + if (ip_route_output(&rt, dst, 0, 0, dev->ifindex)) + return -1; + if (rt->rt_src == 0) { + ip_rt_put(rt); + return -1; + } + + skb=alloc_skb(IGMP_SIZE+dev->hard_header_len+15, GFP_ATOMIC); + if (skb == NULL) { + ip_rt_put(rt); + return -1; + } + + skb->dst = &rt->u.dst; + + skb_reserve(skb, (dev->hard_header_len+15)&~15); + + skb->nh.iph = iph = (struct iphdr *)skb_put(skb, sizeof(struct iphdr)+4); + + iph->version = 4; + iph->ihl = (sizeof(struct iphdr)+4)>>2; + iph->tos = 0; + iph->frag_off = htons(IP_DF); + iph->ttl = 1; + iph->daddr = dst; + iph->saddr = rt->rt_src; + iph->protocol = IPPROTO_IGMP; + iph->tot_len = htons(IGMP_SIZE); + ip_select_ident(iph, &rt->u.dst, NULL); + ((u8*)&iph[1])[0] = IPOPT_RA; + ((u8*)&iph[1])[1] = 4; + ((u8*)&iph[1])[2] = 0; + ((u8*)&iph[1])[3] = 0; + ip_send_check(iph); + + ih = (struct igmphdr *)skb_put(skb, sizeof(struct igmphdr)); + ih->type=type; + ih->code=0; + ih->csum=0; + ih->group=group; + ih->csum=ip_compute_csum((void *)ih, sizeof(struct igmphdr)); + + return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, + output_maybe_reroute); +} + + +static void igmp_timer_expire(unsigned long data) +{ + struct ip_mc_list *im=(struct ip_mc_list *)data; + struct in_device *in_dev = im->interface; + int err; + + spin_lock(&im->lock); + im->tm_running=0; + + if (IGMP_V1_SEEN(in_dev)) + err = igmp_send_report(in_dev->dev, im->multiaddr, IGMP_HOST_MEMBERSHIP_REPORT); + else + err = igmp_send_report(in_dev->dev, im->multiaddr, IGMP_HOST_NEW_MEMBERSHIP_REPORT); + + /* Failed. Retry later. */ + if (err) { + if (!in_dev->dead) + igmp_start_timer(im, IGMP_Unsolicited_Report_Interval); + goto out; + } + + if (im->unsolicit_count) { + im->unsolicit_count--; + igmp_start_timer(im, IGMP_Unsolicited_Report_Interval); + } + im->reporter = 1; +out: + spin_unlock(&im->lock); + ip_ma_put(im); +} + +static void igmp_heard_report(struct in_device *in_dev, u32 group) +{ + struct ip_mc_list *im; + + /* Timers are only set for non-local groups */ + + if (group == IGMP_ALL_HOSTS) + return; + + read_lock(&in_dev->lock); + for (im=in_dev->mc_list; im!=NULL; im=im->next) { + if (im->multiaddr == group) { + igmp_stop_timer(im); + break; + } + } + read_unlock(&in_dev->lock); +} + +static void igmp_heard_query(struct in_device *in_dev, unsigned char max_resp_time, + u32 group) +{ + struct ip_mc_list *im; + int max_delay; + + max_delay = max_resp_time*(HZ/IGMP_TIMER_SCALE); + + if (max_resp_time == 0) { + /* Alas, old v1 router presents here. */ + + max_delay = IGMP_Query_Response_Interval; + in_dev->mr_v1_seen = jiffies + IGMP_V1_Router_Present_Timeout; + group = 0; + } + + /* + * - Start the timers in all of our membership records + * that the query applies to for the interface on + * which the query arrived excl. those that belong + * to a "local" group (224.0.0.X) + * - For timers already running check if they need to + * be reset. + * - Use the igmp->igmp_code field as the maximum + * delay possible + */ + read_lock(&in_dev->lock); + for (im=in_dev->mc_list; im!=NULL; im=im->next) { + if (group && group != im->multiaddr) + continue; + if (im->multiaddr == IGMP_ALL_HOSTS) + continue; + igmp_mod_timer(im, max_delay); + } + read_unlock(&in_dev->lock); +} + +int igmp_rcv(struct sk_buff *skb) +{ + /* This basically follows the spec line by line -- see RFC1112 */ + struct igmphdr *ih = skb->h.igmph; + struct in_device *in_dev = in_dev_get(skb->dev); + int len = skb->len; + + if (in_dev==NULL) { + kfree_skb(skb); + return 0; + } + + if (skb_is_nonlinear(skb)) { + if (skb_linearize(skb, GFP_ATOMIC) != 0) { + kfree_skb(skb); + return -ENOMEM; + } + ih = skb->h.igmph; + } + + if (len < sizeof(struct igmphdr) || ip_compute_csum((void *)ih, len)) { + in_dev_put(in_dev); + kfree_skb(skb); + return 0; + } + + switch (ih->type) { + case IGMP_HOST_MEMBERSHIP_QUERY: + igmp_heard_query(in_dev, ih->code, ih->group); + break; + case IGMP_HOST_MEMBERSHIP_REPORT: + case IGMP_HOST_NEW_MEMBERSHIP_REPORT: + /* Is it our report looped back? */ + if (((struct rtable*)skb->dst)->key.iif == 0) + break; + igmp_heard_report(in_dev, ih->group); + break; + case IGMP_PIM: +#ifdef CONFIG_IP_PIMSM_V1 + in_dev_put(in_dev); + return pim_rcv_v1(skb); +#endif + case IGMP_DVMRP: + case IGMP_TRACE: + case IGMP_HOST_LEAVE_MESSAGE: + case IGMP_MTRACE: + case IGMP_MTRACE_RESP: + break; + default: + NETDEBUG(printk(KERN_DEBUG "New IGMP type=%d, why we do not know about it?\n", ih->type)); + } + in_dev_put(in_dev); + kfree_skb(skb); + return 0; +} + +#endif + + +/* + * Add a filter to a device + */ + +static void ip_mc_filter_add(struct in_device *in_dev, u32 addr) +{ + char buf[MAX_ADDR_LEN]; + struct net_device *dev = in_dev->dev; + + /* Checking for IFF_MULTICAST here is WRONG-WRONG-WRONG. + We will get multicast token leakage, when IFF_MULTICAST + is changed. This check should be done in dev->set_multicast_list + routine. Something sort of: + if (dev->mc_list && dev->flags&IFF_MULTICAST) { do it; } + --ANK + */ + if (arp_mc_map(addr, buf, dev, 0) == 0) + dev_mc_add(dev,buf,dev->addr_len,0); +} + +/* + * Remove a filter from a device + */ + +static void ip_mc_filter_del(struct in_device *in_dev, u32 addr) +{ + char buf[MAX_ADDR_LEN]; + struct net_device *dev = in_dev->dev; + + if (arp_mc_map(addr, buf, dev, 0) == 0) + dev_mc_delete(dev,buf,dev->addr_len,0); +} + +static void igmp_group_dropped(struct ip_mc_list *im) +{ +#ifdef CONFIG_IP_MULTICAST + int reporter; +#endif + + if (im->loaded) { + im->loaded = 0; + ip_mc_filter_del(im->interface, im->multiaddr); + } + +#ifdef CONFIG_IP_MULTICAST + if (im->multiaddr == IGMP_ALL_HOSTS) + return; + + reporter = im->reporter; + igmp_stop_timer(im); + + if (reporter && !IGMP_V1_SEEN(im->interface)) + igmp_send_report(im->interface->dev, im->multiaddr, IGMP_HOST_LEAVE_MESSAGE); +#endif +} + +static void igmp_group_added(struct ip_mc_list *im) +{ + if (im->loaded == 0) { + im->loaded = 1; + ip_mc_filter_add(im->interface, im->multiaddr); + } + +#ifdef CONFIG_IP_MULTICAST + if (im->multiaddr == IGMP_ALL_HOSTS) + return; + + spin_lock_bh(&im->lock); + igmp_start_timer(im, IGMP_Initial_Report_Delay); + spin_unlock_bh(&im->lock); +#endif +} + + +/* + * Multicast list managers + */ + + +/* + * A socket has joined a multicast group on device dev. + */ + +void ip_mc_inc_group(struct in_device *in_dev, u32 addr) +{ + struct ip_mc_list *im; + + ASSERT_RTNL(); + + for (im=in_dev->mc_list; im; im=im->next) { + if (im->multiaddr == addr) { + im->users++; + goto out; + } + } + + im = (struct ip_mc_list *)kmalloc(sizeof(*im), GFP_KERNEL); + if (!im) + goto out; + + im->users=1; + im->interface=in_dev; + in_dev_hold(in_dev); + im->multiaddr=addr; + atomic_set(&im->refcnt, 1); + spin_lock_init(&im->lock); +#ifdef CONFIG_IP_MULTICAST + im->tm_running=0; + init_timer(&im->timer); + im->timer.data=(unsigned long)im; + im->timer.function=&igmp_timer_expire; + im->unsolicit_count = IGMP_Unsolicited_Report_Count; + im->reporter = 0; +#endif + im->loaded = 0; + write_lock_bh(&in_dev->lock); + im->next=in_dev->mc_list; + in_dev->mc_list=im; + write_unlock_bh(&in_dev->lock); + igmp_group_added(im); + if (in_dev->dev->flags & IFF_UP) + ip_rt_multicast_event(in_dev); +out: + return; +} + +/* + * A socket has left a multicast group on device dev + */ + +void ip_mc_dec_group(struct in_device *in_dev, u32 addr) +{ + struct ip_mc_list *i, **ip; + + ASSERT_RTNL(); + + for (ip=&in_dev->mc_list; (i=*ip)!=NULL; ip=&i->next) { + if (i->multiaddr==addr) { + if (--i->users == 0) { + write_lock_bh(&in_dev->lock); + *ip = i->next; + write_unlock_bh(&in_dev->lock); + igmp_group_dropped(i); + + if (in_dev->dev->flags & IFF_UP) + ip_rt_multicast_event(in_dev); + + ip_ma_put(i); + return; + } + break; + } + } +} + +/* Device going down */ + +void ip_mc_down(struct in_device *in_dev) +{ + struct ip_mc_list *i; + + ASSERT_RTNL(); + + for (i=in_dev->mc_list; i; i=i->next) + igmp_group_dropped(i); + + ip_mc_dec_group(in_dev, IGMP_ALL_HOSTS); +} + +/* Device going up */ + +void ip_mc_up(struct in_device *in_dev) +{ + struct ip_mc_list *i; + + ASSERT_RTNL(); + + ip_mc_inc_group(in_dev, IGMP_ALL_HOSTS); + + for (i=in_dev->mc_list; i; i=i->next) + igmp_group_added(i); +} + +/* + * Device is about to be destroyed: clean up. + */ + +void ip_mc_destroy_dev(struct in_device *in_dev) +{ + struct ip_mc_list *i; + + ASSERT_RTNL(); + + write_lock_bh(&in_dev->lock); + while ((i = in_dev->mc_list) != NULL) { + in_dev->mc_list = i->next; + write_unlock_bh(&in_dev->lock); + + igmp_group_dropped(i); + ip_ma_put(i); + + write_lock_bh(&in_dev->lock); + } + write_unlock_bh(&in_dev->lock); +} + +static struct in_device * ip_mc_find_dev(struct ip_mreqn *imr) +{ + struct rtable *rt; + struct net_device *dev = NULL; + struct in_device *idev = NULL; + + if (imr->imr_address.s_addr) { + dev = ip_dev_find(imr->imr_address.s_addr); + if (!dev) + return NULL; + __dev_put(dev); + } + + if (!dev && !ip_route_output(&rt, imr->imr_multiaddr.s_addr, 0, 0, 0)) { + dev = rt->u.dst.dev; + ip_rt_put(rt); + } + if (dev) { + imr->imr_ifindex = dev->ifindex; + idev = __in_dev_get(dev); + } + return idev; +} + +/* + * Join a socket to a group + */ +int sysctl_igmp_max_memberships = IP_MAX_MEMBERSHIPS; + +int ip_mc_join_group(struct sock *sk , struct ip_mreqn *imr) +{ + int err; + u32 addr = imr->imr_multiaddr.s_addr; + struct ip_mc_socklist *iml, *i; + struct in_device *in_dev; + int count = 0; + + if (!MULTICAST(addr)) + return -EINVAL; + + rtnl_shlock(); + + if (!imr->imr_ifindex) + in_dev = ip_mc_find_dev(imr); + else { + in_dev = inetdev_by_index(imr->imr_ifindex); + if (in_dev) + __in_dev_put(in_dev); + } + + if (!in_dev) { + iml = NULL; + err = -ENODEV; + goto done; + } + + iml = (struct ip_mc_socklist *)sock_kmalloc(sk, sizeof(*iml), GFP_KERNEL); + + err = -EADDRINUSE; + for (i=sk->protinfo.af_inet.mc_list; i; i=i->next) { + if (memcmp(&i->multi, imr, sizeof(*imr)) == 0) { + /* New style additions are reference counted */ + if (imr->imr_address.s_addr == 0) { + i->count++; + err = 0; + } + goto done; + } + count++; + } + err = -ENOBUFS; + //if (iml == NULL || count >= sysctl_igmp_max_memberships) + if (iml == NULL || count > sysctl_igmp_max_memberships)// modify for cdrouter v3.3 item 300(cdrouter_mcast_100) bug + goto done; + memcpy(&iml->multi, imr, sizeof(*imr)); + iml->next = sk->protinfo.af_inet.mc_list; + iml->count = 1; + sk->protinfo.af_inet.mc_list = iml; + ip_mc_inc_group(in_dev, addr); + iml = NULL; + err = 0; + +done: + rtnl_shunlock(); + if (iml) + sock_kfree_s(sk, iml, sizeof(*iml)); + return err; +} + +/* + * Ask a socket to leave a group. + */ + +int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr) +{ + struct ip_mc_socklist *iml, **imlp; + + rtnl_lock(); + for (imlp=&sk->protinfo.af_inet.mc_list; (iml=*imlp)!=NULL; imlp=&iml->next) { + if (iml->multi.imr_multiaddr.s_addr==imr->imr_multiaddr.s_addr && + iml->multi.imr_address.s_addr==imr->imr_address.s_addr && + (!imr->imr_ifindex || iml->multi.imr_ifindex==imr->imr_ifindex)) { + struct in_device *in_dev; + if (--iml->count) { + rtnl_unlock(); + return 0; + } + + *imlp = iml->next; + + in_dev = inetdev_by_index(iml->multi.imr_ifindex); + if (in_dev) { + ip_mc_dec_group(in_dev, imr->imr_multiaddr.s_addr); + in_dev_put(in_dev); + } + rtnl_unlock(); + sock_kfree_s(sk, iml, sizeof(*iml)); + return 0; + } + } + rtnl_unlock(); + return -EADDRNOTAVAIL; +} + +/* + * A socket is closing. + */ + +void ip_mc_drop_socket(struct sock *sk) +{ + struct ip_mc_socklist *iml; + + if (sk->protinfo.af_inet.mc_list == NULL) + return; + + rtnl_lock(); + while ((iml=sk->protinfo.af_inet.mc_list) != NULL) { + struct in_device *in_dev; + sk->protinfo.af_inet.mc_list = iml->next; + + if ((in_dev = inetdev_by_index(iml->multi.imr_ifindex)) != NULL) { + ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr); + in_dev_put(in_dev); + } + sock_kfree_s(sk, iml, sizeof(*iml)); + + } + rtnl_unlock(); +} + +int ip_check_mc(struct in_device *in_dev, u32 mc_addr) +{ + struct ip_mc_list *im; + + read_lock(&in_dev->lock); + for (im=in_dev->mc_list; im; im=im->next) { + if (im->multiaddr == mc_addr) { + read_unlock(&in_dev->lock); + return 1; + } + } + read_unlock(&in_dev->lock); + return 0; +} + + +#ifdef CONFIG_IP_MULTICAST + +int ip_mc_procinfo(char *buffer, char **start, off_t offset, int length) +{ + off_t pos=0, begin=0; + struct ip_mc_list *im; + int len=0; + struct net_device *dev; + + len=sprintf(buffer,"Idx\tDevice : Count Querier\tGroup Users Timer\tReporter\n"); + + read_lock(&dev_base_lock); + for(dev = dev_base; dev; dev = dev->next) { + struct in_device *in_dev = in_dev_get(dev); + char *querier = "NONE"; + + if (in_dev == NULL) + continue; + + querier = IGMP_V1_SEEN(in_dev) ? "V1" : "V2"; + + len+=sprintf(buffer+len,"%d\t%-10s: %5d %7s\n", + dev->ifindex, dev->name, dev->mc_count, querier); + + read_lock(&in_dev->lock); + for (im = in_dev->mc_list; im; im = im->next) { + len+=sprintf(buffer+len, + "\t\t\t\t%08lX %5d %d:%08lX\t\t%d\n", + im->multiaddr, im->users, + im->tm_running, im->timer.expires-jiffies, im->reporter); + + pos=begin+len; + if(pos<offset) + { + len=0; + begin=pos; + } + if(pos>offset+length) { + read_unlock(&in_dev->lock); + in_dev_put(in_dev); + goto done; + } + } + read_unlock(&in_dev->lock); + in_dev_put(in_dev); + } +done: + read_unlock(&dev_base_lock); + + *start=buffer+(offset-begin); + len-=(offset-begin); + if(len>length) + len=length; + if(len<0) + len=0; + return len; +} +#endif + |