From 543e3a8da5a4c453e992d5351ef405d5e32f27d7 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 24 Mar 2016 21:56:21 -0500 Subject: netpoll: Fix extra refcount release in netpoll_cleanup() netpoll_setup() does a dev_hold() on np->dev, the netpoll device. If it fails, it correctly does a dev_put() but leaves np->dev set. If we call netpoll_cleanup() after the failure, np->dev is still set so we do another dev_put(), which decrements the refcount an extra time. It's questionable to call netpoll_cleanup() after netpoll_setup() fails, but it can be difficult to find the problem, and we can easily avoid it in this case. The extra decrements can lead to hangs like this: unregister_netdevice: waiting for bond0 to become free. Usage count = -3 Set and clear np->dev at the points where we dev_hold() and dev_put() the device. Signed-off-by: Bjorn Helgaas Signed-off-by: David S. Miller --- net/core/netpoll.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 94acfc89ad97..a57bd17805b4 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -603,7 +603,6 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev) const struct net_device_ops *ops; int err; - np->dev = ndev; strlcpy(np->dev_name, ndev->name, IFNAMSIZ); INIT_WORK(&np->cleanup_work, netpoll_async_cleanup); @@ -670,6 +669,7 @@ int netpoll_setup(struct netpoll *np) goto unlock; } dev_hold(ndev); + np->dev = ndev; if (netdev_master_upper_dev_get(ndev)) { np_err(np, "%s is a slave device, aborting\n", np->dev_name); @@ -770,6 +770,7 @@ int netpoll_setup(struct netpoll *np) return 0; put: + np->dev = NULL; dev_put(ndev); unlock: rtnl_unlock(); -- cgit v1.2.3