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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: Sven Eckelmann <sven@narfation.org>
This commit is contained in:
Sven Eckelmann 2011-05-03 13:10:06 +02:00
parent c3caf5196c
commit 3a4375a9f0
1 changed files with 11 additions and 11 deletions
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22
net/batman-adv/bat_sysfs.c
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@ -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))
goto out;
if (status_tmp == IF_NOT_IN_USE) {
rtnl_lock();
hardif_disable_interface(hard_iface);
rtnl_unlock();
if (!rtnl_trylock()) {
ret = -ERESTARTSYS;
goto out;
}
/* if the interface already is in use */
if (hard_iface->if_status != IF_NOT_IN_USE) {
rtnl_lock();
if (status_tmp == IF_NOT_IN_USE) {
hardif_disable_interface(hard_iface);
rtnl_unlock();
goto unlock;
}
rtnl_lock();
ret = hardif_enable_interface(hard_iface, buff);
rtnl_unlock();
/* if the interface already is in use */
if (hard_iface->if_status != IF_NOT_IN_USE)
hardif_disable_interface(hard_iface);
ret = hardif_enable_interface(hard_iface, buff);
unlock:
rtnl_unlock();
out:
hardif_free_ref(hard_iface);
return ret;