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Subject[PATCH 81/86] ppp: set qdisc_tx_busylock to avoid LOCKDEP splat
3.6.11.1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 0b652fb68c02c1acd0307d3acac4ae7123536031 ]

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>
---
drivers/net/ppp/ppp_generic.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 5c05572..2603b99 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -1021,7 +1021,15 @@ ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
return err;
}

+static struct lock_class_key ppp_tx_busylock;
+static int ppp_dev_init(struct net_device *dev)
+{
+ dev->qdisc_tx_busylock = &ppp_tx_busylock;
+ return 0;
+}
+
static const struct net_device_ops ppp_netdev_ops = {
+ .ndo_init = ppp_dev_init,
.ndo_start_xmit = ppp_start_xmit,
.ndo_do_ioctl = ppp_net_ioctl,
};
--
1.7.10.4



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