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