cregit-Linux how code gets into the kernel

Release 4.11 net/decnet/dn_route.c

Directory: net/decnet
/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Routing Functions (Endnode and Router)
 *
 * Authors:     Steve Whitehouse <SteveW@ACM.org>
 *              Eduardo Marcelo Serrat <emserrat@geocities.com>
 *
 * Changes:
 *              Steve Whitehouse : Fixes to allow "intra-ethernet" and
 *                                 "return-to-sender" bits on outgoing
 *                                 packets.
 *              Steve Whitehouse : Timeouts for cached routes.
 *              Steve Whitehouse : Use dst cache for input routes too.
 *              Steve Whitehouse : Fixed error values in dn_send_skb.
 *              Steve Whitehouse : Rework routing functions to better fit
 *                                 DECnet routing design
 *              Alexey Kuznetsov : New SMP locking
 *              Steve Whitehouse : More SMP locking changes & dn_cache_dump()
 *              Steve Whitehouse : Prerouting NF hook, now really is prerouting.
 *                                 Fixed possible skb leak in rtnetlink funcs.
 *              Steve Whitehouse : Dave Miller's dynamic hash table sizing and
 *                                 Alexey Kuznetsov's finer grained locking
 *                                 from ipv4/route.c.
 *              Steve Whitehouse : Routing is now starting to look like a
 *                                 sensible set of code now, mainly due to
 *                                 my copying the IPv4 routing code. The
 *                                 hooks here are modified and will continue
 *                                 to evolve for a while.
 *              Steve Whitehouse : Real SMP at last :-) Also new netfilter
 *                                 stuff. Look out raw sockets your days
 *                                 are numbered!
 *              Steve Whitehouse : Added return-to-sender functions. Added
 *                                 backlog congestion level return codes.
 *              Steve Whitehouse : Fixed bug where routes were set up with
 *                                 no ref count on net devices.
 *              Steve Whitehouse : RCU for the route cache
 *              Steve Whitehouse : Preparations for the flow cache
 *              Steve Whitehouse : Prepare for nonlinear skbs
 */

/******************************************************************************
    (c) 1995-1998 E.M. Serrat           emserrat@geocities.com

    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
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
*******************************************************************************/

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/inet.h>
#include <linux/route.h>
#include <linux/in_route.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/rtnetlink.h>
#include <linux/string.h>
#include <linux/netfilter_decnet.h>
#include <linux/rcupdate.h>
#include <linux/times.h>
#include <linux/export.h>
#include <asm/errno.h>
#include <net/net_namespace.h>
#include <net/netlink.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/fib_rules.h>
#include <net/dn.h>
#include <net/dn_dev.h>
#include <net/dn_nsp.h>
#include <net/dn_route.h>
#include <net/dn_neigh.h>
#include <net/dn_fib.h>


struct dn_rt_hash_bucket
{
	
struct dn_route __rcu *chain;
	
spinlock_t lock;
};

extern struct neigh_table dn_neigh_table;



static unsigned char dn_hiord_addr[6] = {0xAA,0x00,0x04,0x00,0x00,0x00};


static const int dn_rt_min_delay = 2 * HZ;

static const int dn_rt_max_delay = 10 * HZ;

static const int dn_rt_mtu_expires = 10 * 60 * HZ;


static unsigned long dn_rt_deadline;

static int dn_dst_gc(struct dst_ops *ops);
static struct dst_entry *dn_dst_check(struct dst_entry *, __u32);
static unsigned int dn_dst_default_advmss(const struct dst_entry *dst);
static unsigned int dn_dst_mtu(const struct dst_entry *dst);
static void dn_dst_destroy(struct dst_entry *);
static void dn_dst_ifdown(struct dst_entry *, struct net_device *dev, int how);
static struct dst_entry *dn_dst_negative_advice(struct dst_entry *);
static void dn_dst_link_failure(struct sk_buff *);
static void dn_dst_update_pmtu(struct dst_entry *dst, struct sock *sk,
			       struct sk_buff *skb , u32 mtu);
static void dn_dst_redirect(struct dst_entry *dst, struct sock *sk,
			    struct sk_buff *skb);
static struct neighbour *dn_dst_neigh_lookup(const struct dst_entry *dst,
					     struct sk_buff *skb,
					     const void *daddr);
static int dn_route_input(struct sk_buff *);
static void dn_run_flush(unsigned long dummy);


static struct dn_rt_hash_bucket *dn_rt_hash_table;

static unsigned int dn_rt_hash_mask;


static struct timer_list dn_route_timer;
static DEFINE_TIMER(dn_rt_flush_timer, dn_run_flush, 0, 0);

int decnet_dst_gc_interval = 2;


static struct dst_ops dn_dst_ops = {
	.family =		PF_DECnet,
	.gc_thresh =		128,
	.gc =			dn_dst_gc,
	.check =		dn_dst_check,
	.default_advmss =	dn_dst_default_advmss,
	.mtu =			dn_dst_mtu,
	.cow_metrics =		dst_cow_metrics_generic,
	.destroy =		dn_dst_destroy,
	.ifdown =		dn_dst_ifdown,
	.negative_advice =	dn_dst_negative_advice,
	.link_failure =		dn_dst_link_failure,
	.update_pmtu =		dn_dst_update_pmtu,
	.redirect =		dn_dst_redirect,
	.neigh_lookup =		dn_dst_neigh_lookup,
};




static void dn_dst_destroy(struct dst_entry *dst)
{
	struct dn_route *rt = (struct dn_route *) dst;

	if (rt->n)
		neigh_release(rt->n);
	dst_destroy_metrics_generic(dst);
}


Contributors
PersonTokensPropCommitsCommitProp
David S. Miller41100.00%2100.00%


Total41100.00%2100.00%






static void dn_dst_ifdown(struct dst_entry *dst, struct net_device *dev, int how)
{
	if (how) {
		struct dn_route *rt = (struct dn_route *) dst;
		struct neighbour *n = rt->n;

		if (n && n->dev == dev) {
			n->dev = dev_net(dev)->loopback_dev;
			dev_hold(n->dev);
			dev_put(dev);
		}
	}
}


Contributors
PersonTokensPropCommitsCommitProp
David S. Miller81100.00%1100.00%


Total81100.00%1100.00%






static __inline__ unsigned int dn_hash(__le16 src, __le16 dst)
{
	__u16 tmp = (__u16 __force)(src ^ dst);
	tmp ^= (tmp >> 3);
	tmp ^= (tmp >> 5);
	tmp ^= (tmp >> 10);
	return dn_rt_hash_mask & (unsigned int)tmp;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)4981.67%360.00%


Steven Whitehouse915.00%120.00%


Eric Dumazet23.33%120.00%


Total60100.00%5100.00%






static inline void dnrt_free(struct dn_route *rt)
{
	call_rcu_bh(&rt->dst.rcu_head, dst_rcu_free);
}


Contributors
PersonTokensPropCommitsCommitProp
Steven Whitehouse2291.67%133.33%


Dipankar Sarma14.17%133.33%


Andrew Morton14.17%133.33%


Total24100.00%3100.00%






static inline void dnrt_drop(struct dn_route *rt)
{
	dst_release(&rt->dst);
	call_rcu_bh(&rt->dst.rcu_head, dst_rcu_free);
}


Contributors
PersonTokensPropCommitsCommitProp
Steven Whitehouse3093.75%133.33%


Andrew Morton13.12%133.33%


Dipankar Sarma13.12%133.33%


Total32100.00%3100.00%






static void dn_dst_check_expire(unsigned long dummy)
{
	int i;
	struct dn_route *rt;
	struct dn_route __rcu **rtp;
	unsigned long now = jiffies;
	unsigned long expire = 120 * HZ;

	for (i = 0; i <= dn_rt_hash_mask; i++) {
		rtp = &dn_rt_hash_table[i].chain;

		spin_lock(&dn_rt_hash_table[i].lock);
		while ((rt = rcu_dereference_protected(*rtp,
						lockdep_is_held(&dn_rt_hash_table[i].lock))) != NULL) {
			if (atomic_read(&rt->dst.__refcnt) ||
					(now - rt->dst.lastuse) < expire) {
				rtp = &rt->dst.dn_next;
				continue;
			}
			*rtp = rt->dst.dn_next;
			rt->dst.dn_next = NULL;
			dnrt_free(rt);
		}
		spin_unlock(&dn_rt_hash_table[i].lock);

		if ((jiffies - now) > 0)
			break;
	}

	mod_timer(&dn_route_timer, now + decnet_dst_gc_interval * HZ);
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)16484.54%457.14%


Eric Dumazet2713.92%228.57%


Steven Whitehouse31.55%114.29%


Total194100.00%7100.00%






static int dn_dst_gc(struct dst_ops *ops)
{
	struct dn_route *rt;
	struct dn_route __rcu **rtp;
	int i;
	unsigned long now = jiffies;
	unsigned long expire = 10 * HZ;

	for (i = 0; i <= dn_rt_hash_mask; i++) {

		spin_lock_bh(&dn_rt_hash_table[i].lock);
		rtp = &dn_rt_hash_table[i].chain;

		while ((rt = rcu_dereference_protected(*rtp,
						lockdep_is_held(&dn_rt_hash_table[i].lock))) != NULL) {
			if (atomic_read(&rt->dst.__refcnt) ||
					(now - rt->dst.lastuse) < expire) {
				rtp = &rt->dst.dn_next;
				continue;
			}
			*rtp = rt->dst.dn_next;
			rt->dst.dn_next = NULL;
			dnrt_drop(rt);
			break;
		}
		spin_unlock_bh(&dn_rt_hash_table[i].lock);
	}

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)14280.68%450.00%


Eric Dumazet2715.34%225.00%


Daniel Lezcano42.27%112.50%


Steven Whitehouse31.70%112.50%


Total176100.00%8100.00%



/*
 * The decnet standards don't impose a particular minimum mtu, what they
 * do insist on is that the routing layer accepts a datagram of at least
 * 230 bytes long. Here we have to subtract the routing header length from
 * 230 to get the minimum acceptable mtu. If there is no neighbour, then we
 * assume the worst and use a long header size.
 *
 * We update both the mtu and the advertised mss (i.e. the segment size we
 * advertise to the other end).
 */



static void dn_dst_update_pmtu(struct dst_entry *dst, struct sock *sk,
			       struct sk_buff *skb, u32 mtu)
{
	struct dn_route *rt = (struct dn_route *) dst;
	struct neighbour *n = rt->n;
	u32 min_mtu = 230;
	struct dn_dev *dn;

	dn = n ? rcu_dereference_raw(n->dev->dn_ptr) : NULL;

	if (dn && dn->use_long == 0)
		min_mtu -= 6;
	else
		min_mtu -= 21;

	if (dst_metric(dst, RTAX_MTU) > mtu && mtu >= min_mtu) {
		if (!(dst_metric_locked(dst, RTAX_MTU))) {
			dst_metric_set(dst, RTAX_MTU, mtu);
			dst_set_expires(dst, dn_rt_mtu_expires);
		}
		if (!(dst_metric_locked(dst, RTAX_ADVMSS))) {
			u32 mss = mtu - DN_MAX_NSP_DATA_HEADER;
			u32 existing_mss = dst_metric_raw(dst, RTAX_ADVMSS);
			if (!existing_mss || existing_mss > mss)
				dst_metric_set(dst, RTAX_ADVMSS, mss);
		}
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Steven Whitehouse11763.24%112.50%


David S. Miller5831.35%562.50%


Satoru SATOH73.78%112.50%


Eric Dumazet31.62%112.50%


Total185100.00%8100.00%






static void dn_dst_redirect(struct dst_entry *dst, struct sock *sk,
			    struct sk_buff *skb)
{
}


Contributors
PersonTokensPropCommitsCommitProp
David S. Miller20100.00%2100.00%


Total20100.00%2100.00%



/*
 * When a route has been marked obsolete. (e.g. routing cache flush)
 */



static struct dst_entry *dn_dst_check(struct dst_entry *dst, __u32 cookie)
{
	return NULL;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)19100.00%1100.00%


Total19100.00%1100.00%






static struct dst_entry *dn_dst_negative_advice(struct dst_entry *dst)
{
	dst_release(dst);
	return NULL;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)21100.00%1100.00%


Total21100.00%1100.00%






static void dn_dst_link_failure(struct sk_buff *skb)
{
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)990.00%150.00%


Joe Perches110.00%150.00%


Total10100.00%2100.00%






static inline int compare_keys(struct flowidn *fl1, struct flowidn *fl2)
{
	return ((fl1->daddr ^ fl2->daddr) |
		(fl1->saddr ^ fl2->saddr) |
		(fl1->flowidn_mark ^ fl2->flowidn_mark) |
		(fl1->flowidn_scope ^ fl2->flowidn_scope) |
		(fl1->flowidn_oif ^ fl2->flowidn_oif) |
		(fl1->flowidn_iif ^ fl2->flowidn_iif)) == 0;
}


Contributors
PersonTokensPropCommitsCommitProp
David S. Miller5162.20%266.67%


Steven Whitehouse3137.80%133.33%


Total82100.00%3100.00%






static int dn_insert_route(struct dn_route *rt, unsigned int hash, struct dn_route **rp)
{
	struct dn_route *rth;
	struct dn_route __rcu **rthp;
	unsigned long now = jiffies;

	rthp = &dn_rt_hash_table[hash].chain;

	spin_lock_bh(&dn_rt_hash_table[hash].lock);
	while ((rth = rcu_dereference_protected(*rthp,
						lockdep_is_held(&dn_rt_hash_table[hash].lock))) != NULL) {
		if (compare_keys(&rth->fld, &rt->fld)) {
			/* Put it first */
			*rthp = rth->dst.dn_next;
			rcu_assign_pointer(rth->dst.dn_next,
					   dn_rt_hash_table[hash].chain);
			rcu_assign_pointer(dn_rt_hash_table[hash].chain, rth);

			dst_use(&rth->dst, now);
			spin_unlock_bh(&dn_rt_hash_table[hash].lock);

			dnrt_drop(rt);
			*rp = rth;
			return 0;
		}
		rthp = &rth->dst.dn_next;
	}

	rcu_assign_pointer(rt->dst.dn_next, dn_rt_hash_table[hash].chain);
	rcu_assign_pointer(dn_rt_hash_table[hash].chain, rt);

	dst_use(&rt->dst, now);
	spin_unlock_bh(&dn_rt_hash_table[hash].lock);
	*rp = rt;
	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Steven Whitehouse12852.89%19.09%


Linus Torvalds (pre-git)5924.38%436.36%


Eric Dumazet3112.81%327.27%


Paul E. McKenney166.61%19.09%


Pavel Emelyanov62.48%19.09%


David S. Miller20.83%19.09%


Total242100.00%11100.00%






static void dn_run_flush(unsigned long dummy)
{
	int i;
	struct dn_route *rt, *next;

	for (i = 0; i < dn_rt_hash_mask; i++) {
		spin_lock_bh(&dn_rt_hash_table[i].lock);

		if ((rt = xchg((struct dn_route **)&dn_rt_hash_table[i].chain, NULL)) == NULL)
			goto nothing_to_declare;

		for(; rt; rt = next) {
			next = rcu_dereference_raw(rt->dst.dn_next);
			RCU_INIT_POINTER(rt->dst.dn_next, NULL);
			dst_free((struct