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net: openvswitch: introduce common code for flushing flows 

To avoid some issues, for example RCU usage warning and double free,
we should flush the flows under ovs_lock. This patch refactors
table_instance_destroy and introduces table_instance_flow_flush
which can be invoked by __dp_destroy or ovs_flow_tbl_flush.

Fixes: 50b0e61b32 ("net: openvswitch: fix possible memleak on destroy flow-table")
Reported-by: Johan Knöös <jknoos@google.com>
Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2020-August/050489.html
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tonghao Zhang 2020-08-12 17:56:39 +08:00 committed by David S. Miller
parent 88fd1cb80d
commit 1f3a090b90
3 changed files with 27 additions and 21 deletions
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10
net/openvswitch/datapath.c
View File

@ -1756,6 +1756,7 @@ err:
/* Called with ovs_mutex. */ /* Called with ovs_mutex. */
static void __dp_destroy(struct datapath *dp) static void __dp_destroy(struct datapath *dp)
{ {
struct flow_table *table = &dp->table;
int i; int i;
for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++) { for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++) {
@ -1774,7 +1775,14 @@ static void __dp_destroy(struct datapath *dp)
*/ */
ovs_dp_detach_port(ovs_vport_ovsl(dp, OVSP_LOCAL)); ovs_dp_detach_port(ovs_vport_ovsl(dp, OVSP_LOCAL));
/* RCU destroy the flow table */ /* Flush sw_flow in the tables. RCU cb only releases resource
* such as dp, ports and tables. That may avoid some issues
* such as RCU usage warning.
*/
table_instance_flow_flush(table, ovsl_dereference(table->ti),
ovsl_dereference(table->ufid_ti));
/* RCU destroy the ports, meters and flow tables. */
call_rcu(&dp->rcu, destroy_dp_rcu); call_rcu(&dp->rcu, destroy_dp_rcu);
} }

35
net/openvswitch/flow_table.c
View File

@ -473,19 +473,15 @@ static void table_instance_flow_free(struct flow_table *table,
flow_mask_remove(table, flow->mask); flow_mask_remove(table, flow->mask);
} }
static void table_instance_destroy(struct flow_table *table, /* Must be called with OVS mutex held. */
struct table_instance *ti, void table_instance_flow_flush(struct flow_table *table,
struct table_instance *ufid_ti, struct table_instance *ti,
bool deferred) struct table_instance *ufid_ti)
{ {
int i; int i;
if (!ti)
return;
BUG_ON(!ufid_ti);
if (ti->keep_flows) if (ti->keep_flows)
goto skip_flows; return;
for (i = 0; i < ti->n_buckets; i++) { for (i = 0; i < ti->n_buckets; i++) {
struct sw_flow *flow; struct sw_flow *flow;
@ -497,18 +493,16 @@ static void table_instance_destroy(struct flow_table *table,
table_instance_flow_free(table, ti, ufid_ti, table_instance_flow_free(table, ti, ufid_ti,
flow, false); flow, false);
ovs_flow_free(flow, deferred); ovs_flow_free(flow, true);
} }
} }
}
skip_flows: static void table_instance_destroy(struct table_instance *ti,
if (deferred) { struct table_instance *ufid_ti)
call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb); {
call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb); call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
} else { call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
__table_instance_destroy(ti);
__table_instance_destroy(ufid_ti);
}
} }
/* No need for locking this function is called from RCU callback or /* No need for locking this function is called from RCU callback or
@ -523,7 +517,7 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
call_rcu(&mc->rcu, mask_cache_rcu_cb); call_rcu(&mc->rcu, mask_cache_rcu_cb);
call_rcu(&ma->rcu, mask_array_rcu_cb); call_rcu(&ma->rcu, mask_array_rcu_cb);
table_instance_destroy(table, ti, ufid_ti, false); table_instance_destroy(ti, ufid_ti);
} }
struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti, struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
@ -641,7 +635,8 @@ int ovs_flow_tbl_flush(struct flow_table *flow_table)
flow_table->count = 0; flow_table->count = 0;
flow_table->ufid_count = 0; flow_table->ufid_count = 0;
table_instance_destroy(flow_table, old_ti, old_ufid_ti, true); table_instance_flow_flush(flow_table, old_ti, old_ufid_ti);
table_instance_destroy(old_ti, old_ufid_ti);
return 0; return 0;
err_free_ti: err_free_ti:

3
net/openvswitch/flow_table.h
View File

@ -105,5 +105,8 @@ void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src,
bool full, const struct sw_flow_mask *mask); bool full, const struct sw_flow_mask *mask);
void ovs_flow_masks_rebalance(struct flow_table *table); void ovs_flow_masks_rebalance(struct flow_table *table);
void table_instance_flow_flush(struct flow_table *table,
struct table_instance *ti,
struct table_instance *ufid_ti);
#endif /* flow_table.h */ #endif /* flow_table.h */