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Commit a38e5e23 authored by Simon Horman's avatar Simon Horman Committed by Pablo Neira Ayuso
Browse files

ipvs: use cond_resched_rcu() helper when walking connections 



This avoids the situation where walking of a large number of connections
may prevent scheduling for a long time while also avoiding excessive
calls to rcu_read_unlock() and rcu_read_lock().

Note that in the case of !CONFIG_PREEMPT_RCU this will
add a call to cond_resched().

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent f6f3c437

net/netfilter/ipvs/ip_vs_conn.c

+8 −15
Original line number Diff line number Diff line
@@ -975,8 +975,7 @@ static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos) 
				return cp;

			}

		}

		rcu_read_unlock();

		rcu_read_lock();

		cond_resched_rcu();

	}



	return NULL;
@@ -1015,8 +1014,7 @@ static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos) 
			iter->l = &ip_vs_conn_tab[idx];

			return cp;

		}

		rcu_read_unlock();

		rcu_read_lock();

		cond_resched_rcu();

	}

	iter->l = NULL;

	return NULL;
@@ -1206,17 +1204,13 @@ void ip_vs_random_dropentry(struct net *net) 
	int idx;

	struct ip_vs_conn *cp, *cp_c;



	rcu_read_lock();

	/*

	 * Randomly scan 1/32 of the whole table every second

	 */

	for (idx = 0; idx < (ip_vs_conn_tab_size>>5); idx++) {

		unsigned int hash = net_random() & ip_vs_conn_tab_mask;



		/*

		 *  Lock is actually needed in this loop.

		 */

		rcu_read_lock();



		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {

			if (cp->flags & IP_VS_CONN_F_TEMPLATE)

				/* connection template */
@@ -1252,8 +1246,9 @@ void ip_vs_random_dropentry(struct net *net) 
				__ip_vs_conn_put(cp);

			}

		}

		rcu_read_unlock();

		cond_resched_rcu();

	}

	rcu_read_unlock();

}
@@ -1267,11 +1262,8 @@ static void ip_vs_conn_flush(struct net *net) 
	struct netns_ipvs *ipvs = net_ipvs(net);



flush_again:

	for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {

		/*

		 *  Lock is actually needed in this loop.

		 */

	rcu_read_lock();

	for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {



		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {

			if (!ip_vs_conn_net_eq(cp, net))
@@ -1286,8 +1278,9 @@ static void ip_vs_conn_flush(struct net *net) 
				__ip_vs_conn_put(cp);

			}

		}

		rcu_read_unlock();

		cond_resched_rcu();

	}

	rcu_read_unlock();



	/* the counter may be not NULL, because maybe some conn entries

	   are run by slow timer handler or unhashed but still referred */