Commit fb250385 authored by Antoine Tenart's avatar Antoine Tenart Committed by Jakub Kicinski
Browse files

net-sysfs: take the rtnl lock when accessing xps_cpus_map and num_tc 



Accesses to dev->xps_cpus_map (when using dev->num_tc) should be
protected by the rtnl lock, like we do for netif_set_xps_queue. I didn't
see an actual bug being triggered, but let's be safe here and take the
rtnl lock while accessing the map in sysfs.

Fixes: 184c449f ("net: Add support for XPS with QoS via traffic classes")
Signed-off-by: default avatarAntoine Tenart <atenart@kernel.org>
Reviewed-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 1ad58225

net/core/net-sysfs.c

+22 −7
Original line number Diff line number Diff line
@@ -1317,8 +1317,8 @@ static const struct attribute_group dql_group = { 
static ssize_t xps_cpus_show(struct netdev_queue *queue,

			     char *buf)

{

	int cpu, len, ret, num_tc = 1, tc = 0;

	struct net_device *dev = queue->dev;

	int cpu, len, num_tc = 1, tc = 0;

	struct xps_dev_maps *dev_maps;

	cpumask_var_t mask;

	unsigned long index;
@@ -1328,22 +1328,31 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue, 


	index = get_netdev_queue_index(queue);



	if (!rtnl_trylock())

		return restart_syscall();



	if (dev->num_tc) {

		/* Do not allow XPS on subordinate device directly */

		num_tc = dev->num_tc;

		if (num_tc < 0)

			return -EINVAL;

		if (num_tc < 0) {

			ret = -EINVAL;

			goto err_rtnl_unlock;

		}



		/* If queue belongs to subordinate dev use its map */

		dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;



		tc = netdev_txq_to_tc(dev, index);

		if (tc < 0)

			return -EINVAL;

		if (tc < 0) {

			ret = -EINVAL;

			goto err_rtnl_unlock;

		}

	}



	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))

		return -ENOMEM;

	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {

		ret = -ENOMEM;

		goto err_rtnl_unlock;

	}



	rcu_read_lock();

	dev_maps = rcu_dereference(dev->xps_cpus_map);
@@ -1366,9 +1375,15 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue, 
	}

	rcu_read_unlock();



	rtnl_unlock();



	len = snprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask));

	free_cpumask_var(mask);

	return len < PAGE_SIZE ? len : -EINVAL;



err_rtnl_unlock:

	rtnl_unlock();

	return ret;

}



static ssize_t xps_cpus_store(struct netdev_queue *queue,