net: Explicitly initialize u64_stats_sync structures for lockdep

In order to enable lockdep on seqcount/seqlock structures, we
must explicitly initialize any locks.

The u64_stats_sync structure, uses a seqcount, and thus we need
to introduce a u64_stats_init() function and use it to initialize
the structure.

This unfortunately adds a lot of fairly trivial initialization code
to a number of drivers. But the benefit of ensuring correctness makes
this worth while.

Because these changes are required for lockdep to be enabled, and the
changes are quite trivial, I've not yet split this patch out into 30-some
separate patches, as I figured it would be better to get the various
maintainers thoughts on how to best merge this change along with
the seqcount lockdep enablement.

Feedback would be appreciated!

Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: James Morris <jmorris@namei.org>
Cc: Jesse Gross <jesse@nicira.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Mirko Lindner <mlindner@marvell.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Roger Luethi <rl@hellgate.ch>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Simon Horman <horms@verge.net.au>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Wensong Zhang <wensong@linux-vs.org>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/1381186321-4906-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 21 insertions, 1 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index cfeb85cff4f..5f4617e377b 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1518,6 +1518,7 @@ int snmp_mib_init(void __percpu *ptr[2], size_t mibsize, size_t align)
 	ptr[0] = __alloc_percpu(mibsize, align);
 	if (!ptr[0])
 		return -ENOMEM;
+
 #if SNMP_ARRAY_SZ == 2
 	ptr[1] = __alloc_percpu(mibsize, align);
 	if (!ptr[1]) {
@@ -1561,6 +1562,8 @@ static const struct net_protocol icmp_protocol = {
 
 static __net_init int ipv4_mib_init_net(struct net *net)
 {
+	int i;
+
 	if (snmp_mib_init((void __percpu **)net->mib.tcp_statistics,
 			  sizeof(struct tcp_mib),
 			  __alignof__(struct tcp_mib)) < 0)
@@ -1569,6 +1572,17 @@ static __net_init int ipv4_mib_init_net(struct net *net)
 			  sizeof(struct ipstats_mib),
 			  __alignof__(struct ipstats_mib)) < 0)
 		goto err_ip_mib;
+
+	for_each_possible_cpu(i) {
+		struct ipstats_mib *af_inet_stats;
+		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics[0], i);
+		u64_stats_init(&af_inet_stats->syncp);
+#if SNMP_ARRAY_SZ == 2
+		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics[1], i);
+		u64_stats_init(&af_inet_stats->syncp);
+#endif
+	}
+
 	if (snmp_mib_init((void __percpu **)net->mib.net_statistics,
 			  sizeof(struct linux_mib),
 			  __alignof__(struct linux_mib)) < 0)
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 63a6d6d6b87..caf01176a5e 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -976,13 +976,19 @@ int ip_tunnel_init(struct net_device *dev)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	struct iphdr *iph = &tunnel->parms.iph;
-	int err;
+	int i, err;
 
 	dev->destructor	= ip_tunnel_dev_free;
 	dev->tstats = alloc_percpu(struct pcpu_tstats);
 	if (!dev->tstats)
 		return -ENOMEM;
 
+	for_each_possible_cpu(i) {
+		struct pcpu_tstats *ipt_stats;
+		ipt_stats = per_cpu_ptr(dev->tstats, i);
+		u64_stats_init(&ipt_stats->syncp);
+	}
+
 	err = gro_cells_init(&tunnel->gro_cells, dev);
 	if (err) {
 		free_percpu(dev->tstats);