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| author | Bjorn Helgaas <bhelgaas@google.com> | 2016-03-24 21:56:21 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-03-25 11:23:14 -0400 |
| commit | 543e3a8da5a4c453e992d5351ef405d5e32f27d7 (patch) | |
| tree | bc8514faff2b7548705e02d57b711d7d96843abb | |
| parent | 7dd399130efb5a454daf24075b7563d197114e39 (diff) | |
| download | lwn-543e3a8da5a4c453e992d5351ef405d5e32f27d7.tar.gz lwn-543e3a8da5a4c453e992d5351ef405d5e32f27d7.zip | |
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 <bhelgaas@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/netpoll.c | 3 |
1 files changed, 2 insertions, 1 deletions
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(); |