net/core/dst.c - arm/linux - Git at Google

 /*
  * net/core/dst.c	Protocol independent destination cache.
  *
  * Authors:		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  *
  */

 #include <linux/bitops.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/workqueue.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <net/net_namespace.h>
 #include <linux/sched.h>
 #include <linux/prefetch.h>
 #include <net/lwtunnel.h>

 #include <net/dst.h>
 #include <net/dst_metadata.h>

 /*
  * Theory of operations:
  * 1) We use a list, protected by a spinlock, to add
  *    new entries from both BH and non-BH context.
  * 2) In order to keep spinlock held for a small delay,
  *    we use a second list where are stored long lived
  *    entries, that are handled by the garbage collect thread
  *    fired by a workqueue.
  * 3) This list is guarded by a mutex,
  *    so that the gc_task and dst_dev_event() can be synchronized.
  */

 /*
  * We want to keep lock & list close together
  * to dirty as few cache lines as possible in __dst_free().
  * As this is not a very strong hint, we dont force an alignment on SMP.
  */
 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	kfree_skb(skb);
 	return 0;
 }
 EXPORT_SYMBOL(dst_discard_out);

 const struct dst_metrics dst_default_metrics = {
 	/* This initializer is needed to force linker to place this variable
 	 * into const section. Otherwise it might end into bss section.
 	 * We really want to avoid false sharing on this variable, and catch
 	 * any writes on it.
 	 */
 	.refcnt = REFCOUNT_INIT(1),
 };

 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 	      struct net_device *dev, int initial_ref, int initial_obsolete,
 	      unsigned short flags)
 {
 	dst->child = NULL;
 	dst->dev = dev;
 	if (dev)
 		dev_hold(dev);
 	dst->ops = ops;
 	dst_init_metrics(dst, dst_default_metrics.metrics, true);
 	dst->expires = 0UL;
 	dst->path = dst;
 	dst->from = NULL;
 #ifdef CONFIG_XFRM
 	dst->xfrm = NULL;
 #endif
 	dst->input = dst_discard;
 	dst->output = dst_discard_out;
 	dst->error = 0;
 	dst->obsolete = initial_obsolete;
 	dst->header_len = 0;
 	dst->trailer_len = 0;
 #ifdef CONFIG_IP_ROUTE_CLASSID
 	dst->tclassid = 0;
 #endif
 	dst->lwtstate = NULL;
 	atomic_set(&dst->__refcnt, initial_ref);
 	dst->__use = 0;
 	dst->lastuse = jiffies;
 	dst->flags = flags;
 	dst->next = NULL;
 	if (!(flags & DST_NOCOUNT))
 		dst_entries_add(ops, 1);
 }
 EXPORT_SYMBOL(dst_init);

 void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
 		int initial_ref, int initial_obsolete, unsigned short flags)
 {
 	struct dst_entry *dst;

 	if (ops->gc && dst_entries_get_fast(ops) > ops->gc_thresh) {
 		if (ops->gc(ops))
 			return NULL;
 	}

 	dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
 	if (!dst)
 		return NULL;

 	dst_init(dst, ops, dev, initial_ref, initial_obsolete, flags);

 	return dst;
 }
 EXPORT_SYMBOL(dst_alloc);

 struct dst_entry *dst_destroy(struct dst_entry * dst)
 {
 	struct dst_entry *child;

 	smp_rmb();

 	child = dst->child;

 	if (!(dst->flags & DST_NOCOUNT))
 		dst_entries_add(dst->ops, -1);

 	if (dst->ops->destroy)
 		dst->ops->destroy(dst);
 	if (dst->dev)
 		dev_put(dst->dev);

 	lwtstate_put(dst->lwtstate);

 	if (dst->flags & DST_METADATA)
 		metadata_dst_free((struct metadata_dst *)dst);
 	else
 		kmem_cache_free(dst->ops->kmem_cachep, dst);

 	dst = child;
 	if (dst)
 		dst_release_immediate(dst);
 	return NULL;
 }
 EXPORT_SYMBOL(dst_destroy);

 static void dst_destroy_rcu(struct rcu_head *head)
 {
 	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);

 	dst = dst_destroy(dst);
 }

 /* Operations to mark dst as DEAD and clean up the net device referenced
  * by dst:
  * 1. put the dst under loopback interface and discard all tx/rx packets
  *    on this route.
  * 2. release the net_device
  * This function should be called when removing routes from the fib tree
  * in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to
  * make the next dst_ops->check() fail.
  */
 void dst_dev_put(struct dst_entry *dst)
 {
 	struct net_device *dev = dst->dev;

 	dst->obsolete = DST_OBSOLETE_DEAD;
 	if (dst->ops->ifdown)
 		dst->ops->ifdown(dst, dev, true);
 	dst->input = dst_discard;
 	dst->output = dst_discard_out;
 	dst->dev = dev_net(dst->dev)->loopback_dev;
 	dev_hold(dst->dev);
 	dev_put(dev);
 }
 EXPORT_SYMBOL(dst_dev_put);

 void dst_release(struct dst_entry *dst)
 {
 	if (dst) {
 		int newrefcnt;

 		newrefcnt = atomic_dec_return(&dst->__refcnt);
 		if (unlikely(newrefcnt < 0))
 			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
 					     __func__, dst, newrefcnt);
 		if (!newrefcnt)
 			call_rcu(&dst->rcu_head, dst_destroy_rcu);
 	}
 }
 EXPORT_SYMBOL(dst_release);

 void dst_release_immediate(struct dst_entry *dst)
 {
 	if (dst) {
 		int newrefcnt;

 		newrefcnt = atomic_dec_return(&dst->__refcnt);
 		if (unlikely(newrefcnt < 0))
 			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
 					     __func__, dst, newrefcnt);
 		if (!newrefcnt)
 			dst_destroy(dst);
 	}
 }
 EXPORT_SYMBOL(dst_release_immediate);

 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
 {
 	struct dst_metrics *p = kmalloc(sizeof(*p), GFP_ATOMIC);

 	if (p) {
 		struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old);
 		unsigned long prev, new;

 		refcount_set(&p->refcnt, 1);
 		memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));

 		new = (unsigned long) p;
 		prev = cmpxchg(&dst->_metrics, old, new);

 		if (prev != old) {
 			kfree(p);
 			p = (struct dst_metrics *)__DST_METRICS_PTR(prev);
 			if (prev & DST_METRICS_READ_ONLY)
 				p = NULL;
 		} else if (prev & DST_METRICS_REFCOUNTED) {
 			if (refcount_dec_and_test(&old_p->refcnt))
 				kfree(old_p);
 		}
 	}
 	BUILD_BUG_ON(offsetof(struct dst_metrics, metrics) != 0);
 	return (u32 *)p;
 }
 EXPORT_SYMBOL(dst_cow_metrics_generic);

 /* Caller asserts that dst_metrics_read_only(dst) is false.  */
 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old)
 {
 	unsigned long prev, new;

 	new = ((unsigned long) &dst_default_metrics) | DST_METRICS_READ_ONLY;
 	prev = cmpxchg(&dst->_metrics, old, new);
 	if (prev == old)
 		kfree(__DST_METRICS_PTR(old));
 }
 EXPORT_SYMBOL(__dst_destroy_metrics_generic);

 static struct dst_ops md_dst_ops = {
 	.family =		AF_UNSPEC,
 };

 static int dst_md_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	WARN_ONCE(1, "Attempting to call output on metadata dst\n");
 	kfree_skb(skb);
 	return 0;
 }

 static int dst_md_discard(struct sk_buff *skb)
 {
 	WARN_ONCE(1, "Attempting to call input on metadata dst\n");
 	kfree_skb(skb);
 	return 0;
 }

 static void __metadata_dst_init(struct metadata_dst *md_dst,
 				enum metadata_type type, u8 optslen)

 {
 	struct dst_entry *dst;

 	dst = &md_dst->dst;
 	dst_init(dst, &md_dst_ops, NULL, 1, DST_OBSOLETE_NONE,
 		 DST_METADATA | DST_NOCOUNT);

 	dst->input = dst_md_discard;
 	dst->output = dst_md_discard_out;

 	memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst));
 	md_dst->type = type;
 }

 struct metadata_dst *metadata_dst_alloc(u8 optslen, enum metadata_type type,
 					gfp_t flags)
 {
 	struct metadata_dst *md_dst;

 	md_dst = kmalloc(sizeof(*md_dst) + optslen, flags);
 	if (!md_dst)
 		return NULL;

 	__metadata_dst_init(md_dst, type, optslen);

 	return md_dst;
 }
 EXPORT_SYMBOL_GPL(metadata_dst_alloc);

 void metadata_dst_free(struct metadata_dst *md_dst)
 {
 #ifdef CONFIG_DST_CACHE
 	if (md_dst->type == METADATA_IP_TUNNEL)
 		dst_cache_destroy(&md_dst->u.tun_info.dst_cache);
 #endif
 	kfree(md_dst);
 }

 struct metadata_dst __percpu *
 metadata_dst_alloc_percpu(u8 optslen, enum metadata_type type, gfp_t flags)
 {
 	int cpu;
 	struct metadata_dst __percpu *md_dst;

 	md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen,
 				    __alignof__(struct metadata_dst), flags);
 	if (!md_dst)
 		return NULL;

 	for_each_possible_cpu(cpu)
 		__metadata_dst_init(per_cpu_ptr(md_dst, cpu), type, optslen);

 	return md_dst;
 }
 EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);

 void metadata_dst_free_percpu(struct metadata_dst __percpu *md_dst)
 {
 #ifdef CONFIG_DST_CACHE
 	int cpu;

 	for_each_possible_cpu(cpu) {
 		struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu);

 		if (one_md_dst->type == METADATA_IP_TUNNEL)
 			dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache);
 	}
 #endif
 	free_percpu(md_dst);
 }
 EXPORT_SYMBOL_GPL(metadata_dst_free_percpu);
	/*
	* net/core/dst.c Protocol independent destination cache.
	*
	* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
	*
	*/

	#include <linux/bitops.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/workqueue.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/netdevice.h>
	#include <linux/skbuff.h>
	#include <linux/string.h>
	#include <linux/types.h>
	#include <net/net_namespace.h>
	#include <linux/sched.h>
	#include <linux/prefetch.h>
	#include <net/lwtunnel.h>

	#include <net/dst.h>
	#include <net/dst_metadata.h>

	/*
	* Theory of operations:
	* 1) We use a list, protected by a spinlock, to add
	* new entries from both BH and non-BH context.
	* 2) In order to keep spinlock held for a small delay,
	* we use a second list where are stored long lived
	* entries, that are handled by the garbage collect thread
	* fired by a workqueue.
	* 3) This list is guarded by a mutex,
	* so that the gc_task and dst_dev_event() can be synchronized.
	*/

	/*
	* We want to keep lock & list close together
	* to dirty as few cache lines as possible in __dst_free().
	* As this is not a very strong hint, we dont force an alignment on SMP.
	*/
	int dst_discard_out(struct net net, struct sock sk, struct sk_buff *skb)
	{
	kfree_skb(skb);
	return 0;
	}
	EXPORT_SYMBOL(dst_discard_out);

	const struct dst_metrics dst_default_metrics = {
	/* This initializer is needed to force linker to place this variable
	* into const section. Otherwise it might end into bss section.
	* We really want to avoid false sharing on this variable, and catch
	* any writes on it.
	*/
	.refcnt = REFCOUNT_INIT(1),
	};

	void dst_init(struct dst_entry dst, struct dst_ops ops,
	struct net_device *dev, int initial_ref, int initial_obsolete,
	unsigned short flags)
	{
	dst->child = NULL;
	dst->dev = dev;
	if (dev)
	dev_hold(dev);
	dst->ops = ops;
	dst_init_metrics(dst, dst_default_metrics.metrics, true);
	dst->expires = 0UL;
	dst->path = dst;
	dst->from = NULL;
	#ifdef CONFIG_XFRM
	dst->xfrm = NULL;
	#endif
	dst->input = dst_discard;
	dst->output = dst_discard_out;
	dst->error = 0;
	dst->obsolete = initial_obsolete;
	dst->header_len = 0;
	dst->trailer_len = 0;
	#ifdef CONFIG_IP_ROUTE_CLASSID
	dst->tclassid = 0;
	#endif
	dst->lwtstate = NULL;
	atomic_set(&dst->__refcnt, initial_ref);
	dst->__use = 0;
	dst->lastuse = jiffies;
	dst->flags = flags;
	dst->next = NULL;
	if (!(flags & DST_NOCOUNT))
	dst_entries_add(ops, 1);
	}
	EXPORT_SYMBOL(dst_init);

	void dst_alloc(struct dst_ops ops, struct net_device *dev,
	int initial_ref, int initial_obsolete, unsigned short flags)
	{
	struct dst_entry *dst;

	if (ops->gc && dst_entries_get_fast(ops) > ops->gc_thresh) {
	if (ops->gc(ops))
	return NULL;
	}

	dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
	if (!dst)
	return NULL;

	dst_init(dst, ops, dev, initial_ref, initial_obsolete, flags);

	return dst;
	}
	EXPORT_SYMBOL(dst_alloc);

	struct dst_entry dst_destroy(struct dst_entry dst)
	{
	struct dst_entry *child;

	smp_rmb();

	child = dst->child;

	if (!(dst->flags & DST_NOCOUNT))
	dst_entries_add(dst->ops, -1);

	if (dst->ops->destroy)
	dst->ops->destroy(dst);
	if (dst->dev)
	dev_put(dst->dev);

	lwtstate_put(dst->lwtstate);

	if (dst->flags & DST_METADATA)
	metadata_dst_free((struct metadata_dst *)dst);
	else
	kmem_cache_free(dst->ops->kmem_cachep, dst);

	dst = child;
	if (dst)
	dst_release_immediate(dst);
	return NULL;
	}
	EXPORT_SYMBOL(dst_destroy);

	static void dst_destroy_rcu(struct rcu_head *head)
	{
	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);

	dst = dst_destroy(dst);
	}

	/* Operations to mark dst as DEAD and clean up the net device referenced
	* by dst:
	* 1. put the dst under loopback interface and discard all tx/rx packets
	* on this route.
	* 2. release the net_device
	* This function should be called when removing routes from the fib tree
	* in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to
	* make the next dst_ops->check() fail.
	*/
	void dst_dev_put(struct dst_entry *dst)
	{
	struct net_device *dev = dst->dev;

	dst->obsolete = DST_OBSOLETE_DEAD;
	if (dst->ops->ifdown)
	dst->ops->ifdown(dst, dev, true);
	dst->input = dst_discard;
	dst->output = dst_discard_out;
	dst->dev = dev_net(dst->dev)->loopback_dev;
	dev_hold(dst->dev);
	dev_put(dev);
	}
	EXPORT_SYMBOL(dst_dev_put);

	void dst_release(struct dst_entry *dst)
	{
	if (dst) {
	int newrefcnt;

	newrefcnt = atomic_dec_return(&dst->__refcnt);
	if (unlikely(newrefcnt < 0))
	net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
	__func__, dst, newrefcnt);
	if (!newrefcnt)
	call_rcu(&dst->rcu_head, dst_destroy_rcu);
	}
	}
	EXPORT_SYMBOL(dst_release);

	void dst_release_immediate(struct dst_entry *dst)
	{
	if (dst) {
	int newrefcnt;

	newrefcnt = atomic_dec_return(&dst->__refcnt);
	if (unlikely(newrefcnt < 0))
	net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
	__func__, dst, newrefcnt);
	if (!newrefcnt)
	dst_destroy(dst);
	}
	}
	EXPORT_SYMBOL(dst_release_immediate);

	u32 dst_cow_metrics_generic(struct dst_entry dst, unsigned long old)
	{
	struct dst_metrics p = kmalloc(sizeof(p), GFP_ATOMIC);

	if (p) {
	struct dst_metrics old_p = (struct dst_metrics )__DST_METRICS_PTR(old);
	unsigned long prev, new;

	refcount_set(&p->refcnt, 1);
	memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));

	new = (unsigned long) p;
	prev = cmpxchg(&dst->_metrics, old, new);

	if (prev != old) {
	kfree(p);
	p = (struct dst_metrics *)__DST_METRICS_PTR(prev);
	if (prev & DST_METRICS_READ_ONLY)
	p = NULL;
	} else if (prev & DST_METRICS_REFCOUNTED) {
	if (refcount_dec_and_test(&old_p->refcnt))
	kfree(old_p);
	}
	}
	BUILD_BUG_ON(offsetof(struct dst_metrics, metrics) != 0);
	return (u32 *)p;
	}
	EXPORT_SYMBOL(dst_cow_metrics_generic);

	/* Caller asserts that dst_metrics_read_only(dst) is false. */
	void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old)
	{
	unsigned long prev, new;

	new = ((unsigned long) &dst_default_metrics) \| DST_METRICS_READ_ONLY;
	prev = cmpxchg(&dst->_metrics, old, new);
	if (prev == old)
	kfree(__DST_METRICS_PTR(old));
	}
	EXPORT_SYMBOL(__dst_destroy_metrics_generic);

	static struct dst_ops md_dst_ops = {
	.family = AF_UNSPEC,
	};

	static int dst_md_discard_out(struct net net, struct sock sk, struct sk_buff *skb)
	{
	WARN_ONCE(1, "Attempting to call output on metadata dst\n");
	kfree_skb(skb);
	return 0;
	}

	static int dst_md_discard(struct sk_buff *skb)
	{
	WARN_ONCE(1, "Attempting to call input on metadata dst\n");
	kfree_skb(skb);
	return 0;
	}

	static void __metadata_dst_init(struct metadata_dst *md_dst,
	enum metadata_type type, u8 optslen)

	{
	struct dst_entry *dst;

	dst = &md_dst->dst;
	dst_init(dst, &md_dst_ops, NULL, 1, DST_OBSOLETE_NONE,
	DST_METADATA \| DST_NOCOUNT);

	dst->input = dst_md_discard;
	dst->output = dst_md_discard_out;

	memset(dst + 1, 0, sizeof(md_dst) + optslen - sizeof(dst));
	md_dst->type = type;
	}

	struct metadata_dst *metadata_dst_alloc(u8 optslen, enum metadata_type type,
	gfp_t flags)
	{
	struct metadata_dst *md_dst;

	md_dst = kmalloc(sizeof(*md_dst) + optslen, flags);
	if (!md_dst)
	return NULL;

	__metadata_dst_init(md_dst, type, optslen);

	return md_dst;
	}
	EXPORT_SYMBOL_GPL(metadata_dst_alloc);

	void metadata_dst_free(struct metadata_dst *md_dst)
	{
	#ifdef CONFIG_DST_CACHE
	if (md_dst->type == METADATA_IP_TUNNEL)
	dst_cache_destroy(&md_dst->u.tun_info.dst_cache);
	#endif
	kfree(md_dst);
	}

	struct metadata_dst __percpu *
	metadata_dst_alloc_percpu(u8 optslen, enum metadata_type type, gfp_t flags)
	{
	int cpu;
	struct metadata_dst __percpu *md_dst;

	md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen,
	__alignof__(struct metadata_dst), flags);
	if (!md_dst)
	return NULL;

	for_each_possible_cpu(cpu)
	__metadata_dst_init(per_cpu_ptr(md_dst, cpu), type, optslen);

	return md_dst;
	}
	EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);

	void metadata_dst_free_percpu(struct metadata_dst __percpu *md_dst)
	{
	#ifdef CONFIG_DST_CACHE
	int cpu;

	for_each_possible_cpu(cpu) {
	struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu);

	if (one_md_dst->type == METADATA_IP_TUNNEL)
	dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache);
	}
	#endif
	free_percpu(md_dst);
	}
	EXPORT_SYMBOL_GPL(metadata_dst_free_percpu);