1 files changed, 437 insertions, 0 deletions

diff --git a/net/core/flow.c b/net/core/flow.c
new file mode 100644
index 00000000..a6bda2a5
--- /dev/null
+++ b/net/core/flow.c
@@ -0,0 +1,437 @@
+/* flow.c: Generic flow cache.
+ *
+ * Copyright (C) 2003 Alexey N. Kuznetsov (kuznet@ms2.inr.ac.ru)
+ * Copyright (C) 2003 David S. Miller (davem@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/interrupt.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/completion.h>
+#include <linux/percpu.h>
+#include <linux/bitops.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/mutex.h>
+#include <net/flow.h>
+#include <asm/atomic.h>
+#include <linux/security.h>
+
+struct flow_cache_entry {
+	union {
+		struct hlist_node	hlist;
+		struct list_head	gc_list;
+	} u;
+	u16				family;
+	u8				dir;
+	u32				genid;
+	struct flowi			key;
+	struct flow_cache_object	*object;
+};
+
+struct flow_cache_percpu {
+	struct hlist_head		*hash_table;
+	int				hash_count;
+	u32				hash_rnd;
+	int				hash_rnd_recalc;
+	struct tasklet_struct		flush_tasklet;
+};
+
+struct flow_flush_info {
+	struct flow_cache		*cache;
+	atomic_t			cpuleft;
+	struct completion		completion;
+};
+
+struct flow_cache {
+	u32				hash_shift;
+	struct flow_cache_percpu __percpu *percpu;
+	struct notifier_block		hotcpu_notifier;
+	int				low_watermark;
+	int				high_watermark;
+	struct timer_list		rnd_timer;
+};
+
+atomic_t flow_cache_genid = ATOMIC_INIT(0);
+EXPORT_SYMBOL(flow_cache_genid);
+static struct flow_cache flow_cache_global;
+static struct kmem_cache *flow_cachep __read_mostly;
+
+static DEFINE_SPINLOCK(flow_cache_gc_lock);
+static LIST_HEAD(flow_cache_gc_list);
+
+#define flow_cache_hash_size(cache)	(1 << (cache)->hash_shift)
+#define FLOW_HASH_RND_PERIOD		(10 * 60 * HZ)
+
+static void flow_cache_new_hashrnd(unsigned long arg)
+{
+	struct flow_cache *fc = (void *) arg;
+	int i;
+
+	for_each_possible_cpu(i)
+		per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
+
+	fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+	add_timer(&fc->rnd_timer);
+}
+
+static int flow_entry_valid(struct flow_cache_entry *fle)
+{
+	if (atomic_read(&flow_cache_genid) != fle->genid)
+		return 0;
+	if (fle->object && !fle->object->ops->check(fle->object))
+		return 0;
+	return 1;
+}
+
+static void flow_entry_kill(struct flow_cache_entry *fle)
+{
+	if (fle->object)
+		fle->object->ops->delete(fle->object);
+	kmem_cache_free(flow_cachep, fle);
+}
+
+static void flow_cache_gc_task(struct work_struct *work)
+{
+	struct list_head gc_list;
+	struct flow_cache_entry *fce, *n;
+
+	INIT_LIST_HEAD(&gc_list);
+	spin_lock_bh(&flow_cache_gc_lock);
+	list_splice_tail_init(&flow_cache_gc_list, &gc_list);
+	spin_unlock_bh(&flow_cache_gc_lock);
+
+	list_for_each_entry_safe(fce, n, &gc_list, u.gc_list)
+		flow_entry_kill(fce);
+}
+static DECLARE_WORK(flow_cache_gc_work, flow_cache_gc_task);
+
+static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
+				     int deleted, struct list_head *gc_list)
+{
+	if (deleted) {
+		fcp->hash_count -= deleted;
+		spin_lock_bh(&flow_cache_gc_lock);
+		list_splice_tail(gc_list, &flow_cache_gc_list);
+		spin_unlock_bh(&flow_cache_gc_lock);
+		schedule_work(&flow_cache_gc_work);
+	}
+}
+
+static void __flow_cache_shrink(struct flow_cache *fc,
+				struct flow_cache_percpu *fcp,
+				int shrink_to)
+{
+	struct flow_cache_entry *fle;
+	struct hlist_node *entry, *tmp;
+	LIST_HEAD(gc_list);
+	int i, deleted = 0;
+
+	for (i = 0; i < flow_cache_hash_size(fc); i++) {
+		int saved = 0;
+
+		hlist_for_each_entry_safe(fle, entry, tmp,
+					  &fcp->hash_table[i], u.hlist) {
+			if (saved < shrink_to &&
+			    flow_entry_valid(fle)) {
+				saved++;
+			} else {
+				deleted++;
+				hlist_del(&fle->u.hlist);
+				list_add_tail(&fle->u.gc_list, &gc_list);
+			}
+		}
+	}
+
+	flow_cache_queue_garbage(fcp, deleted, &gc_list);
+}
+
+static void flow_cache_shrink(struct flow_cache *fc,
+			      struct flow_cache_percpu *fcp)
+{
+	int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
+
+	__flow_cache_shrink(fc, fcp, shrink_to);
+}
+
+static void flow_new_hash_rnd(struct flow_cache *fc,
+			      struct flow_cache_percpu *fcp)
+{
+	get_random_bytes(&fcp->hash_rnd, sizeof(u32));
+	fcp->hash_rnd_recalc = 0;
+	__flow_cache_shrink(fc, fcp, 0);
+}
+
+static u32 flow_hash_code(struct flow_cache *fc,
+			  struct flow_cache_percpu *fcp,
+			  const struct flowi *key,
+			  size_t keysize)
+{
+	const u32 *k = (const u32 *) key;
+	const u32 length = keysize * sizeof(flow_compare_t) / sizeof(u32);
+
+	return jhash2(k, length, fcp->hash_rnd)
+		& (flow_cache_hash_size(fc) - 1);
+}
+
+/* I hear what you're saying, use memcmp.  But memcmp cannot make
+ * important assumptions that we can here, such as alignment.
+ */
+static int flow_key_compare(const struct flowi *key1, const struct flowi *key2,
+			    size_t keysize)
+{
+	const flow_compare_t *k1, *k1_lim, *k2;
+
+	k1 = (const flow_compare_t *) key1;
+	k1_lim = k1 + keysize;
+
+	k2 = (const flow_compare_t *) key2;
+
+	do {
+		if (*k1++ != *k2++)
+			return 1;
+	} while (k1 < k1_lim);
+
+	return 0;
+}
+
+struct flow_cache_object *
+flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
+		  flow_resolve_t resolver, void *ctx)
+{
+	struct flow_cache *fc = &flow_cache_global;
+	struct flow_cache_percpu *fcp;
+	struct flow_cache_entry *fle, *tfle;
+	struct hlist_node *entry;
+	struct flow_cache_object *flo;
+	size_t keysize;
+	unsigned int hash;
+
+	local_bh_disable();
+	fcp = this_cpu_ptr(fc->percpu);
+
+	fle = NULL;
+	flo = NULL;
+
+	keysize = flow_key_size(family);
+	if (!keysize)
+		goto nocache;
+
+	/* Packet really early in init?  Making flow_cache_init a
+	 * pre-smp initcall would solve this.  --RR */
+	if (!fcp->hash_table)
+		goto nocache;
+
+	if (fcp->hash_rnd_recalc)
+		flow_new_hash_rnd(fc, fcp);
+
+	hash = flow_hash_code(fc, fcp, key, keysize);
+	hlist_for_each_entry(tfle, entry, &fcp->hash_table[hash], u.hlist) {
+		if (tfle->family == family &&
+		    tfle->dir == dir &&
+		    flow_key_compare(key, &tfle->key, keysize) == 0) {
+			fle = tfle;
+			break;
+		}
+	}
+
+	if (unlikely(!fle)) {
+		if (fcp->hash_count > fc->high_watermark)
+			flow_cache_shrink(fc, fcp);
+
+		fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
+		if (fle) {
+			fle->family = family;
+			fle->dir = dir;
+			memcpy(&fle->key, key, keysize * sizeof(flow_compare_t));
+			fle->object = NULL;
+			hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
+			fcp->hash_count++;
+		}
+	} else if (likely(fle->genid == atomic_read(&flow_cache_genid))) {
+		flo = fle->object;
+		if (!flo)
+			goto ret_object;
+		flo = flo->ops->get(flo);
+		if (flo)
+			goto ret_object;
+	} else if (fle->object) {
+	        flo = fle->object;
+	        flo->ops->delete(flo);
+	        fle->object = NULL;
+	}
+
+nocache:
+	flo = NULL;
+	if (fle) {
+		flo = fle->object;
+		fle->object = NULL;
+	}
+	flo = resolver(net, key, family, dir, flo, ctx);
+	if (fle) {
+		fle->genid = atomic_read(&flow_cache_genid);
+		if (!IS_ERR(flo))
+			fle->object = flo;
+		else
+			fle->genid--;
+	} else {
+		if (flo && !IS_ERR(flo))
+			flo->ops->delete(flo);
+	}
+ret_object:
+	local_bh_enable();
+	return flo;
+}
+EXPORT_SYMBOL(flow_cache_lookup);
+
+static void flow_cache_flush_tasklet(unsigned long data)
+{
+	struct flow_flush_info *info = (void *)data;
+	struct flow_cache *fc = info->cache;
+	struct flow_cache_percpu *fcp;
+	struct flow_cache_entry *fle;
+	struct hlist_node *entry, *tmp;
+	LIST_HEAD(gc_list);
+	int i, deleted = 0;
+
+	fcp = this_cpu_ptr(fc->percpu);
+	for (i = 0; i < flow_cache_hash_size(fc); i++) {
+		hlist_for_each_entry_safe(fle, entry, tmp,
+					  &fcp->hash_table[i], u.hlist) {
+			if (flow_entry_valid(fle))
+				continue;
+
+			deleted++;
+			hlist_del(&fle->u.hlist);
+			list_add_tail(&fle->u.gc_list, &gc_list);
+		}
+	}
+
+	flow_cache_queue_garbage(fcp, deleted, &gc_list);
+
+	if (atomic_dec_and_test(&info->cpuleft))
+		complete(&info->completion);
+}
+
+static void flow_cache_flush_per_cpu(void *data)
+{
+	struct flow_flush_info *info = data;
+	int cpu;
+	struct tasklet_struct *tasklet;
+
+	cpu = smp_processor_id();
+	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
+	tasklet->data = (unsigned long)info;
+	tasklet_schedule(tasklet);
+}
+
+void flow_cache_flush(void)
+{
+	struct flow_flush_info info;
+	static DEFINE_MUTEX(flow_flush_sem);
+
+	/* Don't want cpus going down or up during this. */
+	get_online_cpus();
+	mutex_lock(&flow_flush_sem);
+	info.cache = &flow_cache_global;
+	atomic_set(&info.cpuleft, num_online_cpus());
+	init_completion(&info.completion);
+
+	local_bh_disable();
+	smp_call_function(flow_cache_flush_per_cpu, &info, 0);
+	flow_cache_flush_tasklet((unsigned long)&info);
+	local_bh_enable();
+
+	wait_for_completion(&info.completion);
+	mutex_unlock(&flow_flush_sem);
+	put_online_cpus();
+}
+
+static int __cpuinit flow_cache_cpu_prepare(struct flow_cache *fc, int cpu)
+{
+	struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
+	size_t sz = sizeof(struct hlist_head) * flow_cache_hash_size(fc);
+
+	if (!fcp->hash_table) {
+		fcp->hash_table = kzalloc_node(sz, GFP_KERNEL, cpu_to_node(cpu));
+		if (!fcp->hash_table) {
+			pr_err("NET: failed to allocate flow cache sz %zu\n", sz);
+			return -ENOMEM;
+		}
+		fcp->hash_rnd_recalc = 1;
+		fcp->hash_count = 0;
+		tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
+	}
+	return 0;
+}
+
+static int __cpuinit flow_cache_cpu(struct notifier_block *nfb,
+			  unsigned long action,
+			  void *hcpu)
+{
+	struct flow_cache *fc = container_of(nfb, struct flow_cache, hotcpu_notifier);
+	int res, cpu = (unsigned long) hcpu;
+	struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		res = flow_cache_cpu_prepare(fc, cpu);
+		if (res)
+			return notifier_from_errno(res);
+		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		__flow_cache_shrink(fc, fcp, 0);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static int __init flow_cache_init(struct flow_cache *fc)
+{
+	int i;
+
+	fc->hash_shift = 10;
+	fc->low_watermark = 2 * flow_cache_hash_size(fc);
+	fc->high_watermark = 4 * flow_cache_hash_size(fc);
+
+	fc->percpu = alloc_percpu(struct flow_cache_percpu);
+	if (!fc->percpu)
+		return -ENOMEM;
+
+	for_each_online_cpu(i) {
+		if (flow_cache_cpu_prepare(fc, i))
+			return -ENOMEM;
+	}
+	fc->hotcpu_notifier = (struct notifier_block){
+		.notifier_call = flow_cache_cpu,
+	};
+	register_hotcpu_notifier(&fc->hotcpu_notifier);
+
+	setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
+		    (unsigned long) fc);
+	fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+	add_timer(&fc->rnd_timer);
+
+	return 0;
+}
+
+static int __init flow_cache_init_global(void)
+{
+	flow_cachep = kmem_cache_create("flow_cache",
+					sizeof(struct flow_cache_entry),
+					0, SLAB_PANIC, NULL);
+
+	return flow_cache_init(&flow_cache_global);
+}
+
+module_init(flow_cache_init_global);