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Commit 3a4375a9 authored by Sven Eckelmann's avatar Sven Eckelmann
Browse files

batman-adv: Avoid deadlock between rtnl_lock and s_active 



The hard_if_event is called by the notifier with rtnl_lock and tries to
remove sysfs entries when a NETDEV_UNREGISTER event is received. This
will automatically take the s_active lock.

The s_active lock is also used when a new interface is added to a meshif
through sysfs. In that situation we cannot wait for the rntl_lock before
creating the actual batman-adv interface to prevent a deadlock. It is
still possible to try to get the rtnl_lock and immediately abort the
current operation when the trylock call failed.

Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
parent c3caf519

net/batman-adv/bat_sysfs.c

+9 −9
Original line number Original line Diff line number Diff line
@@ -488,24 +488,24 @@ static ssize_t store_mesh_iface(struct kobject *kobj, struct attribute *attr, 
	    (strncmp(hard_iface->soft_iface->name, buff, IFNAMSIZ) == 0))

	    (strncmp(hard_iface->soft_iface->name, buff, IFNAMSIZ) == 0))

		goto out;

		goto out;





	if (!rtnl_trylock()) {

		ret = -ERESTARTSYS;

		goto out;

	}



	if (status_tmp == IF_NOT_IN_USE) {

	if (status_tmp == IF_NOT_IN_USE) {

		rtnl_lock();

		hardif_disable_interface(hard_iface);

		hardif_disable_interface(hard_iface);

		rtnl_unlock();

		goto unlock;

		goto out;

	}

	}





	/* if the interface already is in use */

	/* if the interface already is in use */

	if (hard_iface->if_status != IF_NOT_IN_USE) {

	if (hard_iface->if_status != IF_NOT_IN_USE)

		rtnl_lock();

		hardif_disable_interface(hard_iface);

		hardif_disable_interface(hard_iface);

		rtnl_unlock();

	}





	rtnl_lock();

	ret = hardif_enable_interface(hard_iface, buff);

	ret = hardif_enable_interface(hard_iface, buff);

	rtnl_unlock();





unlock:

	rtnl_unlock();

out:

out:

	hardif_free_ref(hard_iface);

	hardif_free_ref(hard_iface);

	return ret;

	return ret;