Commit c1742dcb authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: no longer acquire RTNL in threaded_show() 



dev->threaded can be read locklessly, if we add
corresponding READ_ONCE()/WRITE_ONCE() annotations.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240502173926.2010646-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 3e51f2cb

include/linux/netdevice.h

+1 −1
Original line number Diff line number Diff line
@@ -2370,8 +2370,8 @@ struct net_device { 
	struct sfp_bus		*sfp_bus;

	struct lock_class_key	*qdisc_tx_busylock;

	bool			proto_down;

	bool			threaded;

	unsigned		wol_enabled:1;

	unsigned		threaded:1;



	struct list_head	net_notifier_list;

net/core/dev.c

+2 −2
Original line number Diff line number Diff line
@@ -6531,7 +6531,7 @@ int dev_set_threaded(struct net_device *dev, bool threaded) 
		}

	}



	dev->threaded = threaded;

	WRITE_ONCE(dev->threaded, threaded);



	/* Make sure kthread is created before THREADED bit

	 * is set.
@@ -6622,7 +6622,7 @@ void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi, 
	 * threaded mode will not be enabled in napi_enable().

	 */

	if (dev->threaded && napi_kthread_create(napi))

		dev->threaded = 0;

		dev->threaded = false;

	netif_napi_set_irq(napi, -1);

}

EXPORT_SYMBOL(netif_napi_add_weight);

net/core/net-sysfs.c

+4 −4
Original line number Diff line number Diff line
@@ -605,13 +605,13 @@ static ssize_t threaded_show(struct device *dev, 
	struct net_device *netdev = to_net_dev(dev);

	ssize_t ret = -EINVAL;



	if (!rtnl_trylock())

		return restart_syscall();

	rcu_read_lock();



	if (dev_isalive(netdev))

		ret = sysfs_emit(buf, fmt_dec, netdev->threaded);

		ret = sysfs_emit(buf, fmt_dec, READ_ONCE(netdev->threaded));



	rcu_read_unlock();



	rtnl_unlock();

	return ret;

}