1 files changed, 16 insertions, 4 deletions

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 4822aafe638b..c9a15925a1f7 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -102,6 +102,7 @@ struct netconsole_target {
 	struct config_item	item;
 #endif
 	int			enabled;
+	struct mutex		mutex;
 	struct netpoll		np;
 };
 
@@ -181,6 +182,7 @@ static struct netconsole_target *alloc_param_target(char *target_config)
 	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 	nt->np.local_port = 6665;
 	nt->np.remote_port = 6666;
+	mutex_init(&nt->mutex);
 	memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 
 	/* Parse parameters and setup netpoll */
@@ -308,6 +310,7 @@ static ssize_t store_enabled(struct netconsole_target *nt,
 			     const char *buf,
 			     size_t count)
 {
+	unsigned long flags;
 	int enabled;
 	int err;
 
@@ -323,7 +326,6 @@ static ssize_t store_enabled(struct netconsole_target *nt,
 	}
 
 	if (enabled) {	/* 1 */
-
 		/*
 		 * Skip netpoll_parse_options() -- all the attributes are
 		 * already configured via configfs. Just print them out.
@@ -335,8 +337,14 @@ static ssize_t store_enabled(struct netconsole_target *nt,
 			return err;
 
 		printk(KERN_INFO "netconsole: network logging started\n");
-
 	} else {	/* 0 */
+		/* We need to disable the netconsole before cleaning it up
+		 * otherwise we might end up in write_msg() with
+		 * nt->np.dev == NULL and nt->enabled == 1
+		 */
+		spin_lock_irqsave(&target_list_lock, flags);
+		nt->enabled = 0;
+		spin_unlock_irqrestore(&target_list_lock, flags);
 		netpoll_cleanup(&nt->np);
 	}
 
@@ -557,8 +565,10 @@ static ssize_t netconsole_target_attr_store(struct config_item *item,
 	struct netconsole_target_attr *na =
 		container_of(attr, struct netconsole_target_attr, attr);
 
+	mutex_lock(&nt->mutex);
 	if (na->store)
 		ret = na->store(nt, buf, count);
+	mutex_unlock(&nt->mutex);
 
 	return ret;
 }
@@ -597,6 +607,7 @@ static struct config_item *make_netconsole_target(struct config_group *group,
 	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 	nt->np.local_port = 6665;
 	nt->np.remote_port = 6666;
+	mutex_init(&nt->mutex);
 	memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 
 	/* Initialize the config_item member */
@@ -677,12 +688,13 @@ restart:
 			case NETDEV_RELEASE:
 			case NETDEV_JOIN:
 			case NETDEV_UNREGISTER:
-				/*
-				 * rtnl_lock already held
+				/* rtnl_lock already held
 				 * we might sleep in __netpoll_cleanup()
 				 */
 				spin_unlock_irqrestore(&target_list_lock, flags);
+
 				__netpoll_cleanup(&nt->np);
+
 				spin_lock_irqsave(&target_list_lock, flags);
 				dev_put(nt->np.dev);
 				nt->np.dev = NULL;