1 files changed, 266 insertions, 129 deletions

diff --git a/net/core/dst.c b/net/core/dst.c
index 470c05bc4cb..a028409ee43 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -9,60 +9,80 @@
 #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/sched.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/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.
+/*
+ * 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.
  */
-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);
+/*
+ * 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.
+ */
+static struct {
+	spinlock_t		lock;
+	struct dst_entry	*list;
+	unsigned long		timer_inc;
+	unsigned long		timer_expires;
+} dst_garbage = {
+	.lock = __SPIN_LOCK_UNLOCKED(dst_garbage.lock),
+	.timer_inc = DST_GC_MAX,
+};
+static void dst_gc_task(struct work_struct *work);
+static void ___dst_free(struct dst_entry *dst);
+
+static DECLARE_DELAYED_WORK(dst_gc_work, dst_gc_task);
 
-static DEFINE_TIMER(dst_gc_timer, dst_run_gc, DST_GC_MIN, 0);
+static DEFINE_MUTEX(dst_gc_mutex);
+/*
+ * long lived entries are maintained in this list, guarded by dst_gc_mutex
+ */
+static struct dst_entry         *dst_busy_list;
 
-static void dst_run_gc(unsigned long dummy)
+static void dst_gc_task(struct work_struct *work)
 {
 	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;
+	int    work_performed = 0;
+	unsigned long expires = ~0L;
+	struct dst_entry *dst, *next, head;
+	struct dst_entry *last = &head;
+
+	mutex_lock(&dst_gc_mutex);
+	next = dst_busy_list;
+
+loop:
+	while ((dst = next) != NULL) {
+		next = dst->next;
+		prefetch(&next->next);
+		cond_resched();
+		if (likely(atomic_read(&dst->__refcnt))) {
+			last->next = dst;
+			last = dst;
 			delayed++;
 			continue;
 		}
-		*dstp = dst->next;
-		work_performed = 1;
+		work_performed++;
 
 		dst = dst_destroy(dst);
 		if (dst) {
@@ -74,132 +94,160 @@ static void dst_run_gc(unsigned long dummy)
 			 * But we do not have state "obsoleted, but
 			 * referenced by parent", so it is right.
 			 */
-			if (dst->obsolete > 1)
+			if (dst->obsolete > 0)
 				continue;
 
 			___dst_free(dst);
-			dst->next = *dstp;
-			*dstp = dst;
-			dstp = &dst->next;
+			dst->next = next;
+			next = dst;
 		}
 	}
-	if (!dst_garbage_list) {
-		dst_gc_timer_inc = DST_GC_MAX;
-		goto out;
+
+	spin_lock_bh(&dst_garbage.lock);
+	next = dst_garbage.list;
+	if (next) {
+		dst_garbage.list = NULL;
+		spin_unlock_bh(&dst_garbage.lock);
+		goto loop;
 	}
-	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;
+	last->next = NULL;
+	dst_busy_list = head.next;
+	if (!dst_busy_list)
+		dst_garbage.timer_inc = DST_GC_MAX;
+	else {
+		/*
+		 * if we freed less than 1/10 of delayed entries,
+		 * we can sleep longer.
+		 */
+		if (work_performed <= delayed/10) {
+			dst_garbage.timer_expires += dst_garbage.timer_inc;
+			if (dst_garbage.timer_expires > DST_GC_MAX)
+				dst_garbage.timer_expires = DST_GC_MAX;
+			dst_garbage.timer_inc += DST_GC_INC;
+		} else {
+			dst_garbage.timer_inc = DST_GC_INC;
+			dst_garbage.timer_expires = DST_GC_MIN;
+		}
+		expires = dst_garbage.timer_expires;
+		/*
+		 * if the next desired timer is more than 4 seconds in the
+		 * future then round the timer to whole seconds
+		 */
+		if (expires > 4*HZ)
+			expires = round_jiffies_relative(expires);
+		schedule_delayed_work(&dst_gc_work, expires);
 	}
-	dst_gc_timer.expires = jiffies + dst_gc_timer_expires;
-#if RT_CACHE_DEBUG >= 2
-	printk("dst_total: %d/%d %ld\n",
-	       atomic_read(&dst_total), delayed,  dst_gc_timer_expires);
-#endif
-	add_timer(&dst_gc_timer);
 
-out:
-	spin_unlock(&dst_lock);
+	spin_unlock_bh(&dst_garbage.lock);
+	mutex_unlock(&dst_gc_mutex);
 }
 
-static int dst_discard_in(struct sk_buff *skb)
+int dst_discard_sk(struct sock *sk, struct sk_buff *skb)
 {
 	kfree_skb(skb);
 	return 0;
 }
+EXPORT_SYMBOL(dst_discard_sk);
 
-static int dst_discard_out(struct sk_buff *skb)
-{
-	kfree_skb(skb);
-	return 0;
-}
+const u32 dst_default_metrics[RTAX_MAX + 1] = {
+	/* 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.
+	 */
+	[RTAX_MAX] = 0xdeadbeef,
+};
 
-void * dst_alloc(struct dst_ops * ops)
+
+void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
+		int initial_ref, int initial_obsolete, unsigned short flags)
 {
-	struct dst_entry * dst;
+	struct dst_entry *dst;
 
-	if (ops->gc && atomic_read(&ops->entries) > ops->gc_thresh) {
-		if (ops->gc())
+	if (ops->gc && dst_entries_get_fast(ops) > ops->gc_thresh) {
+		if (ops->gc(ops))
 			return NULL;
 	}
-	dst = kmem_cache_alloc(ops->kmem_cachep, SLAB_ATOMIC);
+	dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
 	if (!dst)
 		return NULL;
-	memset(dst, 0, ops->entry_size);
-	atomic_set(&dst->__refcnt, 0);
+	dst->child = NULL;
+	dst->dev = dev;
+	if (dev)
+		dev_hold(dev);
 	dst->ops = ops;
-	dst->lastuse = jiffies;
+	dst_init_metrics(dst, dst_default_metrics, true);
+	dst->expires = 0UL;
 	dst->path = dst;
-	dst->input = dst_discard_in;
-	dst->output = dst_discard_out;
-#if RT_CACHE_DEBUG >= 2 
-	atomic_inc(&dst_total);
+	dst->from = NULL;
+#ifdef CONFIG_XFRM
+	dst->xfrm = NULL;
 #endif
-	atomic_inc(&ops->entries);
+	dst->input = dst_discard;
+	dst->output = dst_discard_sk;
+	dst->error = 0;
+	dst->obsolete = initial_obsolete;
+	dst->header_len = 0;
+	dst->trailer_len = 0;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	dst->tclassid = 0;
+#endif
+	atomic_set(&dst->__refcnt, initial_ref);
+	dst->__use = 0;
+	dst->lastuse = jiffies;
+	dst->flags = flags;
+	dst->pending_confirm = 0;
+	dst->next = NULL;
+	if (!(flags & DST_NOCOUNT))
+		dst_entries_add(ops, 1);
 	return dst;
 }
+EXPORT_SYMBOL(dst_alloc);
 
-static void ___dst_free(struct dst_entry * 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->input = dst_discard;
+		dst->output = dst_discard_sk;
 	}
-	dst->obsolete = 2;
+	dst->obsolete = DST_OBSOLETE_DEAD;
 }
 
-void __dst_free(struct dst_entry * dst)
+void __dst_free(struct dst_entry *dst)
 {
-	spin_lock_bh(&dst_lock);
+	spin_lock_bh(&dst_garbage.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);
+	dst->next = dst_garbage.list;
+	dst_garbage.list = dst;
+	if (dst_garbage.timer_inc > DST_GC_INC) {
+		dst_garbage.timer_inc = DST_GC_INC;
+		dst_garbage.timer_expires = DST_GC_MIN;
+		mod_delayed_work(system_wq, &dst_gc_work,
+				 dst_garbage.timer_expires);
 	}
-	spin_unlock_bh(&dst_lock);
+	spin_unlock_bh(&dst_garbage.lock);
 }
+EXPORT_SYMBOL(__dst_free);
 
 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->flags & DST_NOCOUNT))
+		dst_entries_add(dst->ops, -1);
 
 	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;
@@ -219,6 +267,89 @@ again:
 	}
 	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);
+	if (dst)
+		__dst_free(dst);
+}
+
+void dst_release(struct dst_entry *dst)
+{
+	if (dst) {
+		int newrefcnt;
+
+		newrefcnt = atomic_dec_return(&dst->__refcnt);
+		WARN_ON(newrefcnt < 0);
+		if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt)
+			call_rcu(&dst->rcu_head, dst_destroy_rcu);
+	}
+}
+EXPORT_SYMBOL(dst_release);
+
+u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
+{
+	u32 *p = kmalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC);
+
+	if (p) {
+		u32 *old_p = __DST_METRICS_PTR(old);
+		unsigned long prev, new;
+
+		memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
+
+		new = (unsigned long) p;
+		prev = cmpxchg(&dst->_metrics, old, new);
+
+		if (prev != old) {
+			kfree(p);
+			p = __DST_METRICS_PTR(prev);
+			if (prev & DST_METRICS_READ_ONLY)
+				p = NULL;
+		}
+	}
+	return 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);
+
+/**
+ * __skb_dst_set_noref - sets skb dst, without a reference
+ * @skb: buffer
+ * @dst: dst entry
+ * @force: if force is set, use noref version even for DST_NOCACHE entries
+ *
+ * Sets skb dst, assuming a reference was not taken on dst
+ * skb_dst_drop() should not dst_release() this dst
+ */
+void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst, bool force)
+{
+	WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
+	/* If dst not in cache, we must take a reference, because
+	 * dst_release() will destroy dst as soon as its refcount becomes zero
+	 */
+	if (unlikely((dst->flags & DST_NOCACHE) && !force)) {
+		dst_hold(dst);
+		skb_dst_set(skb, dst);
+	} else {
+		skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
+	}
+}
+EXPORT_SYMBOL(__skb_dst_set_noref);
 
 /* Dirty hack. We did it in 2.2 (in __dst_free),
  * we have _very_ good reasons not to repeat
@@ -228,8 +359,8 @@ again:
  *
  * Commented and originally written by Alexey.
  */
-static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
-			      int unregister)
+static void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
+		       int unregister)
 {
 	if (dst->ops->ifdown)
 		dst->ops->ifdown(dst, dev, unregister);
@@ -238,33 +369,42 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 		return;
 
 	if (!unregister) {
-		dst->input = dst_discard_in;
-		dst->output = dst_discard_out;
+		dst->input = dst_discard;
+		dst->output = dst_discard_sk;
 	} else {
-		dst->dev = &loopback_dev;
-		dev_hold(&loopback_dev);
+		dst->dev = dev_net(dst->dev)->loopback_dev;
+		dev_hold(dst->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)
+static int dst_dev_event(struct notifier_block *this, unsigned long event,
+			 void *ptr)
 {
-	struct net_device *dev = ptr;
-	struct dst_entry *dst;
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct dst_entry *dst, *last = NULL;
 
 	switch (event) {
-	case NETDEV_UNREGISTER:
+	case NETDEV_UNREGISTER_FINAL:
 	case NETDEV_DOWN:
-		spin_lock_bh(&dst_lock);
-		for (dst = dst_garbage_list; dst; dst = dst->next) {
+		mutex_lock(&dst_gc_mutex);
+		for (dst = dst_busy_list; dst; dst = dst->next) {
+			last = dst;
 			dst_ifdown(dst, dev, event != NETDEV_DOWN);
 		}
-		spin_unlock_bh(&dst_lock);
+
+		spin_lock_bh(&dst_garbage.lock);
+		dst = dst_garbage.list;
+		dst_garbage.list = NULL;
+		spin_unlock_bh(&dst_garbage.lock);
+
+		if (last)
+			last->next = dst;
+		else
+			dst_busy_list = dst;
+		for (; dst; dst = dst->next)
+			dst_ifdown(dst, dev, event != NETDEV_DOWN);
+		mutex_unlock(&dst_gc_mutex);
 		break;
 	}
 	return NOTIFY_DONE;
@@ -272,13 +412,10 @@ static int dst_dev_event(struct notifier_block *this, unsigned long event, void
 
 static struct notifier_block dst_dev_notifier = {
 	.notifier_call	= dst_dev_event,
+	.priority = -10, /* must be called after other network notifiers */
 };
 
 void __init dst_init(void)
 {
 	register_netdevice_notifier(&dst_dev_notifier);
 }
-
-EXPORT_SYMBOL(__dst_free);
-EXPORT_SYMBOL(dst_alloc);
-EXPORT_SYMBOL(dst_destroy);