![Alex Wang](/assets/img/avatar_default.png)
Due to the race condition in userspace, there is chance that two
overlapping megaflows could be installed in datapath. And this
causes userspace unable to delete the less inclusive megaflow flow
even after it timeout, since the flow_del logic will stop at the
first match of masked flow.
This commit fixes the bug by making the kernel flow_del and flow_get
logic check all masks in that case.
Introduced by 03f0d916a
(openvswitch: Mega flow implementation).
Signed-off-by: Alex Wang <alexw@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
648 lines
15 KiB
C
648 lines
15 KiB
C
/*
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* Copyright (c) 2007-2013 Nicira, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*/
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#include "flow.h"
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#include "datapath.h"
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#include <linux/uaccess.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/if_ether.h>
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#include <linux/if_vlan.h>
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#include <net/llc_pdu.h>
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#include <linux/kernel.h>
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#include <linux/hash.h>
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#include <linux/jiffies.h>
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#include <linux/llc.h>
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#include <linux/module.h>
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#include <linux/in.h>
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#include <linux/rcupdate.h>
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#include <linux/if_arp.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/sctp.h>
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#include <linux/tcp.h>
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#include <linux/udp.h>
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#include <linux/icmp.h>
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#include <linux/icmpv6.h>
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#include <linux/rculist.h>
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#include <net/ip.h>
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#include <net/ipv6.h>
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#include <net/ndisc.h>
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#define TBL_MIN_BUCKETS 1024
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#define REHASH_INTERVAL (10 * 60 * HZ)
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static struct kmem_cache *flow_cache;
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struct kmem_cache *flow_stats_cache __read_mostly;
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static u16 range_n_bytes(const struct sw_flow_key_range *range)
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{
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return range->end - range->start;
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}
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void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src,
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const struct sw_flow_mask *mask)
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{
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const long *m = (const long *)((const u8 *)&mask->key +
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mask->range.start);
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const long *s = (const long *)((const u8 *)src +
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mask->range.start);
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long *d = (long *)((u8 *)dst + mask->range.start);
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int i;
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/* The memory outside of the 'mask->range' are not set since
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* further operations on 'dst' only uses contents within
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* 'mask->range'.
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*/
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for (i = 0; i < range_n_bytes(&mask->range); i += sizeof(long))
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*d++ = *s++ & *m++;
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}
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struct sw_flow *ovs_flow_alloc(void)
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{
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struct sw_flow *flow;
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struct flow_stats *stats;
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int node;
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flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
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if (!flow)
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return ERR_PTR(-ENOMEM);
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flow->sf_acts = NULL;
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flow->mask = NULL;
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flow->stats_last_writer = NUMA_NO_NODE;
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/* Initialize the default stat node. */
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stats = kmem_cache_alloc_node(flow_stats_cache,
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GFP_KERNEL | __GFP_ZERO, 0);
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if (!stats)
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goto err;
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spin_lock_init(&stats->lock);
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RCU_INIT_POINTER(flow->stats[0], stats);
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for_each_node(node)
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if (node != 0)
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RCU_INIT_POINTER(flow->stats[node], NULL);
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return flow;
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err:
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kmem_cache_free(flow_cache, flow);
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return ERR_PTR(-ENOMEM);
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}
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int ovs_flow_tbl_count(struct flow_table *table)
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{
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return table->count;
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}
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static struct flex_array *alloc_buckets(unsigned int n_buckets)
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{
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struct flex_array *buckets;
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int i, err;
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buckets = flex_array_alloc(sizeof(struct hlist_head),
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n_buckets, GFP_KERNEL);
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if (!buckets)
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return NULL;
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err = flex_array_prealloc(buckets, 0, n_buckets, GFP_KERNEL);
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if (err) {
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flex_array_free(buckets);
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return NULL;
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}
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for (i = 0; i < n_buckets; i++)
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INIT_HLIST_HEAD((struct hlist_head *)
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flex_array_get(buckets, i));
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return buckets;
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}
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static void flow_free(struct sw_flow *flow)
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{
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int node;
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kfree((struct sw_flow_actions __force *)flow->sf_acts);
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for_each_node(node)
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if (flow->stats[node])
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kmem_cache_free(flow_stats_cache,
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(struct flow_stats __force *)flow->stats[node]);
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kmem_cache_free(flow_cache, flow);
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}
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static void rcu_free_flow_callback(struct rcu_head *rcu)
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{
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struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
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flow_free(flow);
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}
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void ovs_flow_free(struct sw_flow *flow, bool deferred)
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{
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if (!flow)
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return;
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if (deferred)
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call_rcu(&flow->rcu, rcu_free_flow_callback);
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else
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flow_free(flow);
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}
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static void free_buckets(struct flex_array *buckets)
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{
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flex_array_free(buckets);
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}
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static void __table_instance_destroy(struct table_instance *ti)
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{
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free_buckets(ti->buckets);
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kfree(ti);
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}
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static struct table_instance *table_instance_alloc(int new_size)
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{
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struct table_instance *ti = kmalloc(sizeof(*ti), GFP_KERNEL);
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if (!ti)
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return NULL;
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ti->buckets = alloc_buckets(new_size);
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if (!ti->buckets) {
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kfree(ti);
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return NULL;
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}
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ti->n_buckets = new_size;
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ti->node_ver = 0;
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ti->keep_flows = false;
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get_random_bytes(&ti->hash_seed, sizeof(u32));
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return ti;
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}
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int ovs_flow_tbl_init(struct flow_table *table)
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{
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struct table_instance *ti;
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ti = table_instance_alloc(TBL_MIN_BUCKETS);
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if (!ti)
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return -ENOMEM;
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rcu_assign_pointer(table->ti, ti);
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INIT_LIST_HEAD(&table->mask_list);
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table->last_rehash = jiffies;
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table->count = 0;
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return 0;
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}
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static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
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{
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struct table_instance *ti = container_of(rcu, struct table_instance, rcu);
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__table_instance_destroy(ti);
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}
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static void table_instance_destroy(struct table_instance *ti, bool deferred)
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{
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int i;
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if (!ti)
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return;
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if (ti->keep_flows)
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goto skip_flows;
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for (i = 0; i < ti->n_buckets; i++) {
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struct sw_flow *flow;
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struct hlist_head *head = flex_array_get(ti->buckets, i);
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struct hlist_node *n;
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int ver = ti->node_ver;
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hlist_for_each_entry_safe(flow, n, head, hash_node[ver]) {
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hlist_del_rcu(&flow->hash_node[ver]);
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ovs_flow_free(flow, deferred);
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}
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}
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skip_flows:
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if (deferred)
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call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
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else
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__table_instance_destroy(ti);
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}
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void ovs_flow_tbl_destroy(struct flow_table *table, bool deferred)
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{
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struct table_instance *ti = ovsl_dereference(table->ti);
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table_instance_destroy(ti, deferred);
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}
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struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
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u32 *bucket, u32 *last)
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{
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struct sw_flow *flow;
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struct hlist_head *head;
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int ver;
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int i;
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ver = ti->node_ver;
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while (*bucket < ti->n_buckets) {
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i = 0;
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head = flex_array_get(ti->buckets, *bucket);
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hlist_for_each_entry_rcu(flow, head, hash_node[ver]) {
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if (i < *last) {
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i++;
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continue;
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}
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*last = i + 1;
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return flow;
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}
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(*bucket)++;
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*last = 0;
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}
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return NULL;
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}
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static struct hlist_head *find_bucket(struct table_instance *ti, u32 hash)
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{
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hash = jhash_1word(hash, ti->hash_seed);
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return flex_array_get(ti->buckets,
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(hash & (ti->n_buckets - 1)));
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}
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static void table_instance_insert(struct table_instance *ti, struct sw_flow *flow)
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{
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struct hlist_head *head;
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head = find_bucket(ti, flow->hash);
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hlist_add_head_rcu(&flow->hash_node[ti->node_ver], head);
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}
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static void flow_table_copy_flows(struct table_instance *old,
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struct table_instance *new)
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{
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int old_ver;
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int i;
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old_ver = old->node_ver;
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new->node_ver = !old_ver;
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/* Insert in new table. */
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for (i = 0; i < old->n_buckets; i++) {
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struct sw_flow *flow;
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struct hlist_head *head;
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head = flex_array_get(old->buckets, i);
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hlist_for_each_entry(flow, head, hash_node[old_ver])
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table_instance_insert(new, flow);
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}
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old->keep_flows = true;
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}
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static struct table_instance *table_instance_rehash(struct table_instance *ti,
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int n_buckets)
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{
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struct table_instance *new_ti;
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new_ti = table_instance_alloc(n_buckets);
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if (!new_ti)
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return NULL;
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flow_table_copy_flows(ti, new_ti);
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return new_ti;
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}
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int ovs_flow_tbl_flush(struct flow_table *flow_table)
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{
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struct table_instance *old_ti;
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struct table_instance *new_ti;
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old_ti = ovsl_dereference(flow_table->ti);
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new_ti = table_instance_alloc(TBL_MIN_BUCKETS);
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if (!new_ti)
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return -ENOMEM;
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rcu_assign_pointer(flow_table->ti, new_ti);
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flow_table->last_rehash = jiffies;
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flow_table->count = 0;
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table_instance_destroy(old_ti, true);
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return 0;
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}
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static u32 flow_hash(const struct sw_flow_key *key, int key_start,
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int key_end)
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{
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const u32 *hash_key = (const u32 *)((const u8 *)key + key_start);
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int hash_u32s = (key_end - key_start) >> 2;
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/* Make sure number of hash bytes are multiple of u32. */
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BUILD_BUG_ON(sizeof(long) % sizeof(u32));
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return arch_fast_hash2(hash_key, hash_u32s, 0);
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}
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static int flow_key_start(const struct sw_flow_key *key)
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{
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if (key->tun_key.ipv4_dst)
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return 0;
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else
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return rounddown(offsetof(struct sw_flow_key, phy),
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sizeof(long));
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}
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static bool cmp_key(const struct sw_flow_key *key1,
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const struct sw_flow_key *key2,
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int key_start, int key_end)
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{
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const long *cp1 = (const long *)((const u8 *)key1 + key_start);
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const long *cp2 = (const long *)((const u8 *)key2 + key_start);
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long diffs = 0;
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int i;
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for (i = key_start; i < key_end; i += sizeof(long))
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diffs |= *cp1++ ^ *cp2++;
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return diffs == 0;
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}
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static bool flow_cmp_masked_key(const struct sw_flow *flow,
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const struct sw_flow_key *key,
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int key_start, int key_end)
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{
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return cmp_key(&flow->key, key, key_start, key_end);
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}
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bool ovs_flow_cmp_unmasked_key(const struct sw_flow *flow,
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struct sw_flow_match *match)
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{
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struct sw_flow_key *key = match->key;
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int key_start = flow_key_start(key);
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int key_end = match->range.end;
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return cmp_key(&flow->unmasked_key, key, key_start, key_end);
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}
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static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
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const struct sw_flow_key *unmasked,
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struct sw_flow_mask *mask)
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{
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struct sw_flow *flow;
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struct hlist_head *head;
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int key_start = mask->range.start;
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int key_end = mask->range.end;
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u32 hash;
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struct sw_flow_key masked_key;
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ovs_flow_mask_key(&masked_key, unmasked, mask);
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hash = flow_hash(&masked_key, key_start, key_end);
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head = find_bucket(ti, hash);
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hlist_for_each_entry_rcu(flow, head, hash_node[ti->node_ver]) {
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if (flow->mask == mask && flow->hash == hash &&
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flow_cmp_masked_key(flow, &masked_key,
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key_start, key_end))
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return flow;
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}
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return NULL;
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}
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struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
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const struct sw_flow_key *key,
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u32 *n_mask_hit)
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{
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struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
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struct sw_flow_mask *mask;
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struct sw_flow *flow;
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*n_mask_hit = 0;
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list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
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(*n_mask_hit)++;
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flow = masked_flow_lookup(ti, key, mask);
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if (flow) /* Found */
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return flow;
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}
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return NULL;
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}
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struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *tbl,
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const struct sw_flow_key *key)
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{
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u32 __always_unused n_mask_hit;
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return ovs_flow_tbl_lookup_stats(tbl, key, &n_mask_hit);
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}
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struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
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struct sw_flow_match *match)
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{
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struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
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struct sw_flow_mask *mask;
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struct sw_flow *flow;
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/* Always called under ovs-mutex. */
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list_for_each_entry(mask, &tbl->mask_list, list) {
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flow = masked_flow_lookup(ti, match->key, mask);
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if (flow && ovs_flow_cmp_unmasked_key(flow, match)) /* Found */
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return flow;
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}
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return NULL;
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}
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int ovs_flow_tbl_num_masks(const struct flow_table *table)
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{
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struct sw_flow_mask *mask;
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int num = 0;
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list_for_each_entry(mask, &table->mask_list, list)
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num++;
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return num;
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}
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static struct table_instance *table_instance_expand(struct table_instance *ti)
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{
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return table_instance_rehash(ti, ti->n_buckets * 2);
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}
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/* Remove 'mask' from the mask list, if it is not needed any more. */
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static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
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{
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if (mask) {
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/* ovs-lock is required to protect mask-refcount and
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* mask list.
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*/
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ASSERT_OVSL();
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BUG_ON(!mask->ref_count);
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mask->ref_count--;
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if (!mask->ref_count) {
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list_del_rcu(&mask->list);
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kfree_rcu(mask, rcu);
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}
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}
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}
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/* Must be called with OVS mutex held. */
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void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
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{
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struct table_instance *ti = ovsl_dereference(table->ti);
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BUG_ON(table->count == 0);
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hlist_del_rcu(&flow->hash_node[ti->node_ver]);
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table->count--;
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/* RCU delete the mask. 'flow->mask' is not NULLed, as it should be
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* accessible as long as the RCU read lock is held.
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*/
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flow_mask_remove(table, flow->mask);
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}
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static struct sw_flow_mask *mask_alloc(void)
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{
|
|
struct sw_flow_mask *mask;
|
|
|
|
mask = kmalloc(sizeof(*mask), GFP_KERNEL);
|
|
if (mask)
|
|
mask->ref_count = 1;
|
|
|
|
return mask;
|
|
}
|
|
|
|
static bool mask_equal(const struct sw_flow_mask *a,
|
|
const struct sw_flow_mask *b)
|
|
{
|
|
const u8 *a_ = (const u8 *)&a->key + a->range.start;
|
|
const u8 *b_ = (const u8 *)&b->key + b->range.start;
|
|
|
|
return (a->range.end == b->range.end)
|
|
&& (a->range.start == b->range.start)
|
|
&& (memcmp(a_, b_, range_n_bytes(&a->range)) == 0);
|
|
}
|
|
|
|
static struct sw_flow_mask *flow_mask_find(const struct flow_table *tbl,
|
|
const struct sw_flow_mask *mask)
|
|
{
|
|
struct list_head *ml;
|
|
|
|
list_for_each(ml, &tbl->mask_list) {
|
|
struct sw_flow_mask *m;
|
|
m = container_of(ml, struct sw_flow_mask, list);
|
|
if (mask_equal(mask, m))
|
|
return m;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/* Add 'mask' into the mask list, if it is not already there. */
|
|
static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
|
|
struct sw_flow_mask *new)
|
|
{
|
|
struct sw_flow_mask *mask;
|
|
mask = flow_mask_find(tbl, new);
|
|
if (!mask) {
|
|
/* Allocate a new mask if none exsits. */
|
|
mask = mask_alloc();
|
|
if (!mask)
|
|
return -ENOMEM;
|
|
mask->key = new->key;
|
|
mask->range = new->range;
|
|
list_add_rcu(&mask->list, &tbl->mask_list);
|
|
} else {
|
|
BUG_ON(!mask->ref_count);
|
|
mask->ref_count++;
|
|
}
|
|
|
|
flow->mask = mask;
|
|
return 0;
|
|
}
|
|
|
|
/* Must be called with OVS mutex held. */
|
|
int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
|
|
struct sw_flow_mask *mask)
|
|
{
|
|
struct table_instance *new_ti = NULL;
|
|
struct table_instance *ti;
|
|
int err;
|
|
|
|
err = flow_mask_insert(table, flow, mask);
|
|
if (err)
|
|
return err;
|
|
|
|
flow->hash = flow_hash(&flow->key, flow->mask->range.start,
|
|
flow->mask->range.end);
|
|
ti = ovsl_dereference(table->ti);
|
|
table_instance_insert(ti, flow);
|
|
table->count++;
|
|
|
|
/* Expand table, if necessary, to make room. */
|
|
if (table->count > ti->n_buckets)
|
|
new_ti = table_instance_expand(ti);
|
|
else if (time_after(jiffies, table->last_rehash + REHASH_INTERVAL))
|
|
new_ti = table_instance_rehash(ti, ti->n_buckets);
|
|
|
|
if (new_ti) {
|
|
rcu_assign_pointer(table->ti, new_ti);
|
|
table_instance_destroy(ti, true);
|
|
table->last_rehash = jiffies;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Initializes the flow module.
|
|
* Returns zero if successful or a negative error code. */
|
|
int ovs_flow_init(void)
|
|
{
|
|
BUILD_BUG_ON(__alignof__(struct sw_flow_key) % __alignof__(long));
|
|
BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long));
|
|
|
|
flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
|
|
+ (num_possible_nodes()
|
|
* sizeof(struct flow_stats *)),
|
|
0, 0, NULL);
|
|
if (flow_cache == NULL)
|
|
return -ENOMEM;
|
|
|
|
flow_stats_cache
|
|
= kmem_cache_create("sw_flow_stats", sizeof(struct flow_stats),
|
|
0, SLAB_HWCACHE_ALIGN, NULL);
|
|
if (flow_stats_cache == NULL) {
|
|
kmem_cache_destroy(flow_cache);
|
|
flow_cache = NULL;
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Uninitializes the flow module. */
|
|
void ovs_flow_exit(void)
|
|
{
|
|
kmem_cache_destroy(flow_stats_cache);
|
|
kmem_cache_destroy(flow_cache);
|
|
}
|