From 3a4375a9f0080e6ae40af63e2e2c1e70a6dcb775 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Tue, 3 May 2011 13:10:06 +0200 Subject: [PATCH] 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 --- net/batman-adv/bat_sysfs.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/net/batman-adv/bat_sysfs.c b/net/batman-adv/bat_sysfs.c index 85ba20d98a66..497a0700cc3c 100644 --- a/net/batman-adv/bat_sysfs.c +++ b/net/batman-adv/bat_sysfs.c @@ -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;