net/core/dst.c - kernel/msm - Gitiles

 /*
  * 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/mm.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/string.h>
 #include <linux/types.h>

 #include <net/dst.h>

 /* Locking strategy:
  * 1) Garbage collection state of dead destination cache
  *    entries is protected by dst_lock.
  * 2) GC is run only from BH context, and is the only remover
  *    of entries.
  * 3) Entries are added to the garbage list from both BH
  *    and non-BH context, so local BH disabling is needed.
  * 4) All operations modify state, so a spinlock is used.
  */
 static struct dst_entry 	*dst_garbage_list;
 #if RT_CACHE_DEBUG >= 2
 static atomic_t			 dst_total = ATOMIC_INIT(0);
 #endif
 static DEFINE_SPINLOCK(dst_lock);

 static unsigned long dst_gc_timer_expires;
 static unsigned long dst_gc_timer_inc = DST_GC_MAX;
 static void dst_run_gc(unsigned long);
 static void ___dst_free(struct dst_entry * dst);

 static DEFINE_TIMER(dst_gc_timer, dst_run_gc, DST_GC_MIN, 0);

 static void dst_run_gc(unsigned long dummy)
 {
 	int    delayed = 0;
 	int    work_performed;
 	struct dst_entry * dst, **dstp;

 	if (!spin_trylock(&dst_lock)) {
 		mod_timer(&dst_gc_timer, jiffies + HZ/10);
 		return;
 	}

 	del_timer(&dst_gc_timer);
 	dstp = &dst_garbage_list;
 	work_performed = 0;
 	while ((dst = *dstp) != NULL) {
 		if (atomic_read(&dst->__refcnt)) {
 			dstp = &dst->next;
 			delayed++;
 			continue;
 		}
 		*dstp = dst->next;
 		work_performed = 1;

 		dst = dst_destroy(dst);
 		if (dst) {
 			/* NOHASH and still referenced. Unless it is already
 			 * on gc list, invalidate it and add to gc list.
 			 *
 			 * Note: this is temporary. Actually, NOHASH dst's
 			 * must be obsoleted when parent is obsoleted.
 			 * But we do not have state "obsoleted, but
 			 * referenced by parent", so it is right.
 			 */
 			if (dst->obsolete > 1)
 				continue;

 			___dst_free(dst);
 			dst->next = *dstp;
 			*dstp = dst;
 			dstp = &dst->next;
 		}
 	}
 	if (!dst_garbage_list) {
 		dst_gc_timer_inc = DST_GC_MAX;
 		goto out;
 	}
 	if (!work_performed) {
 		if ((dst_gc_timer_expires += dst_gc_timer_inc) > DST_GC_MAX)
 			dst_gc_timer_expires = DST_GC_MAX;
 		dst_gc_timer_inc += DST_GC_INC;
 	} else {
 		dst_gc_timer_inc = DST_GC_INC;
 		dst_gc_timer_expires = DST_GC_MIN;
 	}
 #if RT_CACHE_DEBUG >= 2
 	printk("dst_total: %d/%d %ld\n",
 	       atomic_read(&dst_total), delayed,  dst_gc_timer_expires);
 #endif
 	/* if the next desired timer is more than 4 seconds in the future
 	 * then round the timer to whole seconds
 	 */
 	if (dst_gc_timer_expires > 4*HZ)
 		mod_timer(&dst_gc_timer,
 			round_jiffies(jiffies + dst_gc_timer_expires));
 	else
 		mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);

 out:
 	spin_unlock(&dst_lock);
 }

 static int dst_discard_in(struct sk_buff *skb)
 {
 	kfree_skb(skb);
 	return 0;
 }

 static int dst_discard_out(struct sk_buff *skb)
 {
 	kfree_skb(skb);
 	return 0;
 }

 void * dst_alloc(struct dst_ops * ops)
 {
 	struct dst_entry * dst;

 	if (ops->gc && atomic_read(&ops->entries) > ops->gc_thresh) {
 		if (ops->gc())
 			return NULL;
 	}
 	dst = kmem_cache_zalloc(ops->kmem_cachep, GFP_ATOMIC);
 	if (!dst)
 		return NULL;
 	atomic_set(&dst->__refcnt, 0);
 	dst->ops = ops;
 	dst->lastuse = jiffies;
 	dst->path = dst;
 	dst->input = dst_discard_in;
 	dst->output = dst_discard_out;
 #if RT_CACHE_DEBUG >= 2
 	atomic_inc(&dst_total);
 #endif
 	atomic_inc(&ops->entries);
 	return dst;
 }

 static void ___dst_free(struct dst_entry * dst)
 {
 	/* The first case (dev==NULL) is required, when
 	   protocol module is unloaded.
 	 */
 	if (dst->dev == NULL || !(dst->dev->flags&IFF_UP)) {
 		dst->input = dst_discard_in;
 		dst->output = dst_discard_out;
 	}
 	dst->obsolete = 2;
 }

 void __dst_free(struct dst_entry * dst)
 {
 	spin_lock_bh(&dst_lock);
 	___dst_free(dst);
 	dst->next = dst_garbage_list;
 	dst_garbage_list = dst;
 	if (dst_gc_timer_inc > DST_GC_INC) {
 		dst_gc_timer_inc = DST_GC_INC;
 		dst_gc_timer_expires = DST_GC_MIN;
 		mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);
 	}
 	spin_unlock_bh(&dst_lock);
 }

 struct dst_entry *dst_destroy(struct dst_entry * dst)
 {
 	struct dst_entry *child;
 	struct neighbour *neigh;
 	struct hh_cache *hh;

 	smp_rmb();

 again:
 	neigh = dst->neighbour;
 	hh = dst->hh;
 	child = dst->child;

 	dst->hh = NULL;
 	if (hh && atomic_dec_and_test(&hh->hh_refcnt))
 		kfree(hh);

 	if (neigh) {
 		dst->neighbour = NULL;
 		neigh_release(neigh);
 	}

 	atomic_dec(&dst->ops->entries);

 	if (dst->ops->destroy)
 		dst->ops->destroy(dst);
 	if (dst->dev)
 		dev_put(dst->dev);
 #if RT_CACHE_DEBUG >= 2
 	atomic_dec(&dst_total);
 #endif
 	kmem_cache_free(dst->ops->kmem_cachep, dst);

 	dst = child;
 	if (dst) {
 		int nohash = dst->flags & DST_NOHASH;

 		if (atomic_dec_and_test(&dst->__refcnt)) {
 			/* We were real parent of this dst, so kill child. */
 			if (nohash)
 				goto again;
 		} else {
 			/* Child is still referenced, return it for freeing. */
 			if (nohash)
 				return dst;
 			/* Child is still in his hash table */
 		}
 	}
 	return NULL;
 }

 /* Dirty hack. We did it in 2.2 (in __dst_free),
  * we have _very_ good reasons not to repeat
  * this mistake in 2.3, but we have no choice
  * now. _It_ _is_ _explicit_ _deliberate_
  * _race_ _condition_.
  *
  * Commented and originally written by Alexey.
  */
 static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 			      int unregister)
 {
 	if (dst->ops->ifdown)
 		dst->ops->ifdown(dst, dev, unregister);

 	if (dev != dst->dev)
 		return;

 	if (!unregister) {
 		dst->input = dst_discard_in;
 		dst->output = dst_discard_out;
 	} else {
 		dst->dev = &loopback_dev;
 		dev_hold(&loopback_dev);
 		dev_put(dev);
 		if (dst->neighbour && dst->neighbour->dev == dev) {
 			dst->neighbour->dev = &loopback_dev;
 			dev_put(dev);
 			dev_hold(&loopback_dev);
 		}
 	}
 }

 static int dst_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
 {
 	struct net_device *dev = ptr;
 	struct dst_entry *dst;

 	switch (event) {
 	case NETDEV_UNREGISTER:
 	case NETDEV_DOWN:
 		spin_lock_bh(&dst_lock);
 		for (dst = dst_garbage_list; dst; dst = dst->next) {
 			dst_ifdown(dst, dev, event != NETDEV_DOWN);
 		}
 		spin_unlock_bh(&dst_lock);
 		break;
 	}
 	return NOTIFY_DONE;
 }

 static struct notifier_block dst_dev_notifier = {
 	.notifier_call	= dst_dev_event,
 };

 void __init dst_init(void)
 {
 	register_netdevice_notifier(&dst_dev_notifier);
 }

 EXPORT_SYMBOL(__dst_free);
 EXPORT_SYMBOL(dst_alloc);
 EXPORT_SYMBOL(dst_destroy);
	/*
	* 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/mm.h>
	#include <linux/module.h>
	#include <linux/netdevice.h>
	#include <linux/skbuff.h>
	#include <linux/string.h>
	#include <linux/types.h>

	#include <net/dst.h>

	/* Locking strategy:
	* 1) Garbage collection state of dead destination cache
	* entries is protected by dst_lock.
	* 2) GC is run only from BH context, and is the only remover
	* of entries.
	* 3) Entries are added to the garbage list from both BH
	* and non-BH context, so local BH disabling is needed.
	* 4) All operations modify state, so a spinlock is used.
	*/
	static struct dst_entry *dst_garbage_list;
	#if RT_CACHE_DEBUG >= 2
	static atomic_t dst_total = ATOMIC_INIT(0);
	#endif
	static DEFINE_SPINLOCK(dst_lock);

	static unsigned long dst_gc_timer_expires;
	static unsigned long dst_gc_timer_inc = DST_GC_MAX;
	static void dst_run_gc(unsigned long);
	static void ___dst_free(struct dst_entry * dst);

	static DEFINE_TIMER(dst_gc_timer, dst_run_gc, DST_GC_MIN, 0);

	static void dst_run_gc(unsigned long dummy)
	{
	int delayed = 0;
	int work_performed;
	struct dst_entry * dst, **dstp;

	if (!spin_trylock(&dst_lock)) {
	mod_timer(&dst_gc_timer, jiffies + HZ/10);
	return;
	}

	del_timer(&dst_gc_timer);
	dstp = &dst_garbage_list;
	work_performed = 0;
	while ((dst = *dstp) != NULL) {
	if (atomic_read(&dst->__refcnt)) {
	dstp = &dst->next;
	delayed++;
	continue;
	}
	*dstp = dst->next;
	work_performed = 1;

	dst = dst_destroy(dst);
	if (dst) {
	/* NOHASH and still referenced. Unless it is already
	* on gc list, invalidate it and add to gc list.
	*
	* Note: this is temporary. Actually, NOHASH dst's
	* must be obsoleted when parent is obsoleted.
	* But we do not have state "obsoleted, but
	* referenced by parent", so it is right.
	*/
	if (dst->obsolete > 1)
	continue;

	___dst_free(dst);
	dst->next = *dstp;
	*dstp = dst;
	dstp = &dst->next;
	}
	}
	if (!dst_garbage_list) {
	dst_gc_timer_inc = DST_GC_MAX;
	goto out;
	}
	if (!work_performed) {
	if ((dst_gc_timer_expires += dst_gc_timer_inc) > DST_GC_MAX)
	dst_gc_timer_expires = DST_GC_MAX;
	dst_gc_timer_inc += DST_GC_INC;
	} else {
	dst_gc_timer_inc = DST_GC_INC;
	dst_gc_timer_expires = DST_GC_MIN;
	}
	#if RT_CACHE_DEBUG >= 2
	printk("dst_total: %d/%d %ld\n",
	atomic_read(&dst_total), delayed, dst_gc_timer_expires);
	#endif
	/* if the next desired timer is more than 4 seconds in the future
	* then round the timer to whole seconds
	*/
	if (dst_gc_timer_expires > 4*HZ)
	mod_timer(&dst_gc_timer,
	round_jiffies(jiffies + dst_gc_timer_expires));
	else
	mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);

	out:
	spin_unlock(&dst_lock);
	}

	static int dst_discard_in(struct sk_buff *skb)
	{
	kfree_skb(skb);
	return 0;
	}

	static int dst_discard_out(struct sk_buff *skb)
	{
	kfree_skb(skb);
	return 0;
	}

	void * dst_alloc(struct dst_ops * ops)
	{
	struct dst_entry * dst;

	if (ops->gc && atomic_read(&ops->entries) > ops->gc_thresh) {
	if (ops->gc())
	return NULL;
	}
	dst = kmem_cache_zalloc(ops->kmem_cachep, GFP_ATOMIC);
	if (!dst)
	return NULL;
	atomic_set(&dst->__refcnt, 0);
	dst->ops = ops;
	dst->lastuse = jiffies;
	dst->path = dst;
	dst->input = dst_discard_in;
	dst->output = dst_discard_out;
	#if RT_CACHE_DEBUG >= 2
	atomic_inc(&dst_total);
	#endif
	atomic_inc(&ops->entries);
	return dst;
	}

	static void ___dst_free(struct dst_entry * dst)
	{
	/* The first case (dev==NULL) is required, when
	protocol module is unloaded.
	*/
	if (dst->dev == NULL \|\| !(dst->dev->flags&IFF_UP)) {
	dst->input = dst_discard_in;
	dst->output = dst_discard_out;
	}
	dst->obsolete = 2;
	}

	void __dst_free(struct dst_entry * dst)
	{
	spin_lock_bh(&dst_lock);
	___dst_free(dst);
	dst->next = dst_garbage_list;
	dst_garbage_list = dst;
	if (dst_gc_timer_inc > DST_GC_INC) {
	dst_gc_timer_inc = DST_GC_INC;
	dst_gc_timer_expires = DST_GC_MIN;
	mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);
	}
	spin_unlock_bh(&dst_lock);
	}

	struct dst_entry dst_destroy(struct dst_entry dst)
	{
	struct dst_entry *child;
	struct neighbour *neigh;
	struct hh_cache *hh;

	smp_rmb();

	again:
	neigh = dst->neighbour;
	hh = dst->hh;
	child = dst->child;

	dst->hh = NULL;
	if (hh && atomic_dec_and_test(&hh->hh_refcnt))
	kfree(hh);

	if (neigh) {
	dst->neighbour = NULL;
	neigh_release(neigh);
	}

	atomic_dec(&dst->ops->entries);

	if (dst->ops->destroy)
	dst->ops->destroy(dst);
	if (dst->dev)
	dev_put(dst->dev);
	#if RT_CACHE_DEBUG >= 2
	atomic_dec(&dst_total);
	#endif
	kmem_cache_free(dst->ops->kmem_cachep, dst);

	dst = child;
	if (dst) {
	int nohash = dst->flags & DST_NOHASH;

	if (atomic_dec_and_test(&dst->__refcnt)) {
	/* We were real parent of this dst, so kill child. */
	if (nohash)
	goto again;
	} else {
	/* Child is still referenced, return it for freeing. */
	if (nohash)
	return dst;
	/* Child is still in his hash table */
	}
	}
	return NULL;
	}

	/* Dirty hack. We did it in 2.2 (in __dst_free),
	* we have _very_ good reasons not to repeat
	* this mistake in 2.3, but we have no choice
	* now. _It_ _is_ _explicit_ _deliberate_
	* _race_ _condition_.
	*
	* Commented and originally written by Alexey.
	*/
	static inline void dst_ifdown(struct dst_entry dst, struct net_device dev,
	int unregister)
	{
	if (dst->ops->ifdown)
	dst->ops->ifdown(dst, dev, unregister);

	if (dev != dst->dev)
	return;

	if (!unregister) {
	dst->input = dst_discard_in;
	dst->output = dst_discard_out;
	} else {
	dst->dev = &loopback_dev;
	dev_hold(&loopback_dev);
	dev_put(dev);
	if (dst->neighbour && dst->neighbour->dev == dev) {
	dst->neighbour->dev = &loopback_dev;
	dev_put(dev);
	dev_hold(&loopback_dev);
	}
	}
	}

	static int dst_dev_event(struct notifier_block this, unsigned long event, void ptr)
	{
	struct net_device *dev = ptr;
	struct dst_entry *dst;

	switch (event) {
	case NETDEV_UNREGISTER:
	case NETDEV_DOWN:
	spin_lock_bh(&dst_lock);
	for (dst = dst_garbage_list; dst; dst = dst->next) {
	dst_ifdown(dst, dev, event != NETDEV_DOWN);
	}
	spin_unlock_bh(&dst_lock);
	break;
	}
	return NOTIFY_DONE;
	}

	static struct notifier_block dst_dev_notifier = {
	.notifier_call = dst_dev_event,
	};

	void __init dst_init(void)
	{
	register_netdevice_notifier(&dst_dev_notifier);
	}

	EXPORT_SYMBOL(__dst_free);
	EXPORT_SYMBOL(dst_alloc);
	EXPORT_SYMBOL(dst_destroy);