ppp: set qdisc_tx_busylock to avoid LOCKDEP splat
[ Upstream commit
303c07db487be59ae9fda10600ea65ca11c21497 ]
If a qdisc is installed on a ppp device, its possible to get
a lockdep splat under stress, because nested dev_queue_xmit() can
lock busylock a second time (on a different device, so its a false
positive)
Avoid this problem using a distinct lock_class_key for ppp
devices.
Reported-by: Yanko Kaneti <yaneti@declera.com>
Tested-by: Yanko Kaneti <yaneti@declera.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>