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ppp: set qdisc_tx_busylock to avoid LOCKDEP splat

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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>
This commit is contained in:
Eric Dumazet 2013-02-19 10:42:03 -08:00 • committed by David S. Miller
commit 303c07db48
1 changed files with 8 additions and 0 deletions
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8
drivers/net/ppp/ppp_generic.c
View file

@ -1058,7 +1058,15 @@ ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
return stats64; return stats64;
} }
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 = { static const struct net_device_ops ppp_netdev_ops = {
.ndo_init = ppp_dev_init,
.ndo_start_xmit = ppp_start_xmit, .ndo_start_xmit = ppp_start_xmit,
.ndo_do_ioctl = ppp_net_ioctl, .ndo_do_ioctl = ppp_net_ioctl,
.ndo_get_stats64 = ppp_get_stats64, .ndo_get_stats64 = ppp_get_stats64,