Commit 68b6394a authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net-sysfs: get rid of rps_dev_flow_lock 



Use unrcu_pointer() and xchg() in store_rps_dev_flow_table_cnt()
instead of a dedicated spinlock.

Make a similar change in rx_queue_release(), so that both
functions use a similar construct and synchronization.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260302181432.1836150-6-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent dd378109

net/core/net-sysfs.c

+6 −12
Original line number Diff line number Diff line
@@ -1084,7 +1084,6 @@ static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue, 
{

	unsigned long mask, count;

	struct rps_dev_flow_table *table, *old_table;

	static DEFINE_SPINLOCK(rps_dev_flow_lock);

	int rc;



	if (!capable(CAP_NET_ADMIN))
@@ -1128,11 +1127,8 @@ static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue, 
		table = NULL;

	}



	spin_lock(&rps_dev_flow_lock);

	old_table = rcu_dereference_protected(queue->rps_flow_table,

					      lockdep_is_held(&rps_dev_flow_lock));

	rcu_assign_pointer(queue->rps_flow_table, table);

	spin_unlock(&rps_dev_flow_lock);

	old_table = unrcu_pointer(xchg(&queue->rps_flow_table,

				       RCU_INITIALIZER(table)));



	if (old_table)

		call_rcu(&old_table->rcu, rps_dev_flow_table_release);
@@ -1161,8 +1157,8 @@ static void rx_queue_release(struct kobject *kobj) 
{

	struct netdev_rx_queue *queue = to_rx_queue(kobj);

#ifdef CONFIG_RPS

	struct rps_dev_flow_table *old_table;

	struct rps_map *map;

	struct rps_dev_flow_table *flow_table;



	map = rcu_dereference_protected(queue->rps_map, 1);

	if (map) {
@@ -1170,11 +1166,9 @@ static void rx_queue_release(struct kobject *kobj) 
		kfree_rcu(map, rcu);

	}



	flow_table = rcu_dereference_protected(queue->rps_flow_table, 1);

	if (flow_table) {

		RCU_INIT_POINTER(queue->rps_flow_table, NULL);

		call_rcu(&flow_table->rcu, rps_dev_flow_table_release);

	}

	old_table = unrcu_pointer(xchg(&queue->rps_flow_table, NULL));

	if (old_table)

		call_rcu(&old_table->rcu, rps_dev_flow_table_release);

#endif



	memset(kobj, 0, sizeof(*kobj));