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Message-ID: <20120607205356.GA2491@electric-eye.fr.zoreil.com>
Date: Thu, 7 Jun 2012 22:53:56 +0200
From: Francois Romieu <romieu@...zoreil.com>
To: Denys Fedoryshchenko <denys@...p.net.lb>
Cc: davem@...emloft.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: Deadlock, L2TP over IP are not working, 3.4.1
Denys Fedoryshchenko <denys@...p.net.lb> :
[...]
> [ 8683.927442] ======================================================
> [ 8683.927555] [ INFO: possible circular locking dependency detected ]
> [ 8683.927672] 3.4.1-build-0061 #14 Not tainted
> [ 8683.927782] -------------------------------------------------------
> [ 8683.927895] swapper/0/0 is trying to acquire lock:
> [ 8683.928007] (slock-AF_INET){+.-...}, at: [<e0fc73ec>]
> l2tp_xmit_skb+0x173/0x47e [l2tp_core]
> [ 8683.928121]
> [ 8683.928121] but task is already holding lock:
> [ 8683.928121] (_xmit_ETHER#2){+.-...}, at: [<c02f062d>]
> sch_direct_xmit+0x36/0x119
> [ 8683.928121]
> [ 8683.928121] which lock already depends on the new lock.
Any reason why it could not be made LLTX ?
(untested patch against -git, applies to 3.4.1 with some offset)
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 443591d..5725258 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -36,12 +36,20 @@
/* Default device name. May be overridden by name specified by user */
#define L2TP_ETH_DEV_NAME "l2tpeth%d"
+struct l2tp_eth_stats {
+ u64 packets;
+ u64 bytes;
+ struct u64_stats_sync syncp;
+};
+
/* via netdev_priv() */
struct l2tp_eth {
struct net_device *dev;
struct sock *tunnel_sock;
struct l2tp_session *session;
struct list_head list;
+ struct l2tp_eth_stats rstats;
+ struct l2tp_eth_stats tstats;
};
/* via l2tp_session_priv() */
@@ -87,25 +95,56 @@ static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct l2tp_eth *priv = netdev_priv(dev);
struct l2tp_session *session = priv->session;
+ struct l2tp_eth_stats *tstats = &priv->tstats;
l2tp_xmit_skb(session, skb, session->hdr_len);
- dev->stats.tx_bytes += skb->len;
- dev->stats.tx_packets++;
+ u64_stats_update_begin(&tstats->syncp);
+ tstats->packets++;
+ tstats->bytes += skb->len;
+ u64_stats_update_end(&tstats->syncp);
return 0;
}
+static struct rtnl_link_stats64 *
+l2tp_eth_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
+{
+ struct l2tp_eth *priv = netdev_priv(dev);
+ struct l2tp_eth_stats *s;
+ unsigned int start;
+
+ s = &priv->rstats;
+ do {
+ start = u64_stats_fetch_begin_bh(&s->syncp);
+ stats->rx_packets = s->packets;
+ stats->rx_bytes = s->bytes;
+ } while (u64_stats_fetch_retry_bh(&s->syncp, start));
+
+ s = &priv->tstats;
+ do {
+ start = u64_stats_fetch_begin_bh(&s->syncp);
+ stats->tx_packets = s->packets;
+ stats->tx_bytes = s->bytes;
+ } while (u64_stats_fetch_retry_bh(&s->syncp, start));
+
+ stats->rx_errors = dev->stats.rx_errors;
+
+ return stats;
+}
+
static struct net_device_ops l2tp_eth_netdev_ops = {
.ndo_init = l2tp_eth_dev_init,
.ndo_uninit = l2tp_eth_dev_uninit,
.ndo_start_xmit = l2tp_eth_dev_xmit,
+ .ndo_get_stats64 = l2tp_eth_get_stats64,
};
static void l2tp_eth_dev_setup(struct net_device *dev)
{
ether_setup(dev);
- dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+ dev->features |= NETIF_F_LLTX;
+ dev->priv_flags &= ~IFF_TX_SKB_SHARING;
dev->netdev_ops = &l2tp_eth_netdev_ops;
dev->destructor = free_netdev;
}
@@ -139,8 +178,13 @@ static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb,
nf_reset(skb);
if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
- dev->stats.rx_packets++;
- dev->stats.rx_bytes += data_len;
+ struct l2tp_eth *priv = netdev_priv(dev);
+ struct l2tp_eth_stats *rstats = &priv->rstats;
+
+ u64_stats_update_begin(&rstats->syncp);
+ rstats->packets++;
+ rstats->bytes += data_len;
+ u64_stats_update_end(&rstats->syncp);
} else
dev->stats.rx_errors++;
--
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