Commit 1f3a090b authored by Tonghao Zhang's avatar Tonghao Zhang Committed by David S. Miller
Browse files

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: 50b0e61b ("net: openvswitch: fix possible memleak on destroy flow-table")
Reported-by: default avatarJohan Knöös <jknoos@google.com>
Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2020-August/050489.html


Signed-off-by: default avatarTonghao Zhang <xiangxia.m.yue@gmail.com>
Reviewed-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 88fd1cb8

net/openvswitch/datapath.c

+9 −1
Original line number Diff line number Diff line
@@ -1756,6 +1756,7 @@ err: 
/* Called with ovs_mutex. */

static void __dp_destroy(struct datapath *dp)

{

	struct flow_table *table = &dp->table;

	int 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));



	/* 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);

}

net/openvswitch/flow_table.c

+15 −20
Original line number Diff line number Diff line
@@ -473,19 +473,15 @@ static void table_instance_flow_free(struct flow_table *table, 
	flow_mask_remove(table, flow->mask);

}



static void table_instance_destroy(struct flow_table *table,

/* Must be called with OVS mutex held. */

void table_instance_flow_flush(struct flow_table *table,

			       struct table_instance *ti,

				   struct table_instance *ufid_ti,

				   bool deferred)

			       struct table_instance *ufid_ti)

{

	int i;



	if (!ti)

		return;



	BUG_ON(!ufid_ti);

	if (ti->keep_flows)

		goto skip_flows;

		return;



	for (i = 0; i < ti->n_buckets; i++) {

		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,

						 flow, false);

			ovs_flow_free(flow, deferred);

			ovs_flow_free(flow, true);

		}

	}

}



skip_flows:

	if (deferred) {

static void table_instance_destroy(struct table_instance *ti,

				   struct table_instance *ufid_ti)

{

	call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);

	call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);

	} else {

		__table_instance_destroy(ti);

		__table_instance_destroy(ufid_ti);

	}

}



/* 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(&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,
@@ -641,7 +635,8 @@ int ovs_flow_tbl_flush(struct flow_table *flow_table) 
	flow_table->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;



err_free_ti:

net/openvswitch/flow_table.h

+3 −0
Original line number Diff line number Diff line
@@ -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);



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 */

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