[PATCH 4/8] batman-adv: Avoid deadlock between rtnl_lock and s_active
From: Sven Eckelmann <hidden>
Date: 2011-05-08 15:24:40
Also in:
batman
Subsystem:
batman advanced, the rest · Maintainers:
Marek Lindner, Simon Wunderlich, Antonio Quartulli, Sven Eckelmann, Linus Torvalds
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 <redacted> --- net/batman-adv/bat_sysfs.c | 18 +++++++++--------- 1 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/net/batman-adv/bat_sysfs.c b/net/batman-adv/bat_sysfs.c
index 85ba20d..497a070 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 (!rtnl_trylock()) { + ret = -ERESTARTSYS; + goto out; + } + if (status_tmp == IF_NOT_IN_USE) { - rtnl_lock(); hardif_disable_interface(hard_iface); - rtnl_unlock(); - goto out; + goto unlock; } /* if the interface already is in use */ - if (hard_iface->if_status != IF_NOT_IN_USE) { - rtnl_lock(); + if (hard_iface->if_status != IF_NOT_IN_USE) hardif_disable_interface(hard_iface); - rtnl_unlock(); - } - rtnl_lock(); ret = hardif_enable_interface(hard_iface, buff); + +unlock: rtnl_unlock(); - out: hardif_free_ref(hard_iface); return ret;
--
1.7.5.1