diff mbox

[2/2] batman-adv: Avoid deadlock between rtnl_lock and s_active

Message ID 1304421006-7137-1-git-send-email-linus.luessing@web.de (mailing list archive)
State Accepted, archived
Headers

Commit Message

Linus Lüssing May 3, 2011, 11:10 a.m. UTC 
  From: Sven Eckelmann <sven@narfation.org>

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>
---
 bat_sysfs.c |   18 +++++++++---------
 1 files changed, 9 insertions(+), 9 deletions(-)

Comments

Marek Lindner May 4, 2011, 2:57 p.m. UTC | #1 
On Tuesday 03 May 2011 13:10:06 Linus Lüssing wrote:
> From: Sven Eckelmann <sven@narfation.org>
> 
> 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.

Applied in b278a6c.

Thanks,
Marek
diff mbox

Patch

diff --git a/bat_sysfs.c b/bat_sysfs.c
index 85ba20d..497a070 100644
--- a/bat_sysfs.c
+++ b/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);
-	rtnl_unlock();
 
+unlock:
+	rtnl_unlock();
 out:
 	hardif_free_ref(hard_iface);
 	return ret;