IPVS: Use global mutex in ip_vs_app.c

As part of the work to make IPVS network namespace aware
__ip_vs_app_mutex was replaced by a per-namespace lock,
ipvs->app_mutex. ipvs->app_key is also supplied for debugging purposes.

Unfortunately this implementation results in ipvs->app_key residing
in non-static storage which at the very least causes a lockdep warning.

This patch takes the rather heavy-handed approach of reinstating
__ip_vs_app_mutex which will cover access to the ipvs->list_head
of all network namespaces.

[   12.610000] IPVS: Creating netns size=2456 id=0
[   12.630000] IPVS: Registered protocols (TCP, UDP, SCTP, AH, ESP)
[   12.640000] BUG: key ffff880003bbf1a0 not in .data!
[   12.640000] ------------[ cut here ]------------
[   12.640000] WARNING: at kernel/lockdep.c:2701 lockdep_init_map+0x37b/0x570()
[   12.640000] Hardware name: Bochs
[   12.640000] Pid: 1, comm: swapper Tainted: G        W 2.6.38-kexec-06330-g69b7efe-dirty #122
[   12.650000] Call Trace:
[   12.650000]  [<ffffffff8102e685>] warn_slowpath_common+0x75/0xb0
[   12.650000]  [<ffffffff8102e6d5>] warn_slowpath_null+0x15/0x20
[   12.650000]  [<ffffffff8105967b>] lockdep_init_map+0x37b/0x570
[   12.650000]  [<ffffffff8105829d>] ? trace_hardirqs_on+0xd/0x10
[   12.650000]  [<ffffffff81055ad8>] debug_mutex_init+0x38/0x50
[   12.650000]  [<ffffffff8104bc4c>] __mutex_init+0x5c/0x70
[   12.650000]  [<ffffffff81685ee7>] __ip_vs_app_init+0x64/0x86
[   12.660000]  [<ffffffff81685a3b>] ? ip_vs_init+0x0/0xff
[   12.660000]  [<ffffffff811b1c33>] T.620+0x43/0x170
[   12.660000]  [<ffffffff811b1e9a>] ? register_pernet_subsys+0x1a/0x40
[   12.660000]  [<ffffffff81685a3b>] ? ip_vs_init+0x0/0xff
[   12.660000]  [<ffffffff81685a3b>] ? ip_vs_init+0x0/0xff
[   12.660000]  [<ffffffff811b1db7>] register_pernet_operations+0x57/0xb0
[   12.660000]  [<ffffffff81685a3b>] ? ip_vs_init+0x0/0xff
[   12.670000]  [<ffffffff811b1ea9>] register_pernet_subsys+0x29/0x40
[   12.670000]  [<ffffffff81685f19>] ip_vs_app_init+0x10/0x12
[   12.670000]  [<ffffffff81685a87>] ip_vs_init+0x4c/0xff
[   12.670000]  [<ffffffff8166562c>] do_one_initcall+0x7a/0x12e
[   12.670000]  [<ffffffff8166583e>] kernel_init+0x13e/0x1c2
[   12.670000]  [<ffffffff8128c134>] kernel_thread_helper+0x4/0x10
[   12.670000]  [<ffffffff8128ad40>] ? restore_args+0x0/0x30
[   12.680000]  [<ffffffff81665700>] ? kernel_init+0x0/0x1c2
[   12.680000]  [<ffffffff8128c130>] ? kernel_thread_helper+0x0/0x1global0
Signed-off-by: Simon Horman <horms@verge.net.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Julian Anastasov <ja@ssi.bg>
Cc: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_vs.h

@@ -801,8 +801,6 @@ struct netns_ipvs {
 	struct list_head	rs_table[IP_VS_RTAB_SIZE];
 	/* ip_vs_app */
 	struct list_head	app_list;
-	struct mutex		app_mutex;
-	struct lock_class_key	app_key;	/* mutex debuging */
 
 	/* ip_vs_proto */
 	#define IP_VS_PROTO_TAB_SIZE	32	/* must be power of 2 */

net/netfilter/ipvs/ip_vs_app.c

@@ -43,6 +43,8 @@ EXPORT_SYMBOL(register_ip_vs_app);
 EXPORT_SYMBOL(unregister_ip_vs_app);
 EXPORT_SYMBOL(register_ip_vs_app_inc);
 
+static DEFINE_MUTEX(__ip_vs_app_mutex);
+
 /*
  *	Get an ip_vs_app object
  */
@@ -167,14 +169,13 @@ int
 register_ip_vs_app_inc(struct net *net, struct ip_vs_app *app, __u16 proto,
 		       __u16 port)
 {
-	struct netns_ipvs *ipvs = net_ipvs(net);
 	int result;
 
-	mutex_lock(&ipvs->app_mutex);
+	mutex_lock(&__ip_vs_app_mutex);
 
 	result = ip_vs_app_inc_new(net, app, proto, port);
 
-	mutex_unlock(&ipvs->app_mutex);
+	mutex_unlock(&__ip_vs_app_mutex);
 
 	return result;
 }
@@ -189,11 +190,11 @@ int register_ip_vs_app(struct net *net, struct ip_vs_app *app)
 	/* increase the module use count */
 	ip_vs_use_count_inc();
 
-	mutex_lock(&ipvs->app_mutex);
+	mutex_lock(&__ip_vs_app_mutex);
 
 	list_add(&app->a_list, &ipvs->app_list);
 
-	mutex_unlock(&ipvs->app_mutex);
+	mutex_unlock(&__ip_vs_app_mutex);
 
 	return 0;
 }
@@ -205,10 +206,9 @@ int register_ip_vs_app(struct net *net, struct ip_vs_app *app)
  */
 void unregister_ip_vs_app(struct net *net, struct ip_vs_app *app)
 {
-	struct netns_ipvs *ipvs = net_ipvs(net);
 	struct ip_vs_app *inc, *nxt;
 
-	mutex_lock(&ipvs->app_mutex);
+	mutex_lock(&__ip_vs_app_mutex);
 
 	list_for_each_entry_safe(inc, nxt, &app->incs_list, a_list) {
 		ip_vs_app_inc_release(net, inc);
@@ -216,7 +216,7 @@ void unregister_ip_vs_app(struct net *net, struct ip_vs_app *app)
 
 	list_del(&app->a_list);
 
-	mutex_unlock(&ipvs->app_mutex);
+	mutex_unlock(&__ip_vs_app_mutex);
 
 	/* decrease the module use count */
 	ip_vs_use_count_dec();
@@ -501,7 +501,7 @@ static void *ip_vs_app_seq_start(struct seq_file *seq, loff_t *pos)
 	struct net *net = seq_file_net(seq);
 	struct netns_ipvs *ipvs = net_ipvs(net);
 
-	mutex_lock(&ipvs->app_mutex);
+	mutex_lock(&__ip_vs_app_mutex);
 
 	return *pos ? ip_vs_app_idx(ipvs, *pos - 1) : SEQ_START_TOKEN;
 }
@@ -535,9 +535,7 @@ static void *ip_vs_app_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 
 static void ip_vs_app_seq_stop(struct seq_file *seq, void *v)
 {
-	struct netns_ipvs *ipvs = net_ipvs(seq_file_net(seq));
-
-	mutex_unlock(&ipvs->app_mutex);
+	mutex_unlock(&__ip_vs_app_mutex);
 }
 
 static int ip_vs_app_seq_show(struct seq_file *seq, void *v)
@@ -583,7 +581,6 @@ static int __net_init __ip_vs_app_init(struct net *net)
 	struct netns_ipvs *ipvs = net_ipvs(net);
 
 	INIT_LIST_HEAD(&ipvs->app_list);
-	__mutex_init(&ipvs->app_mutex, "ipvs->app_mutex", &ipvs->app_key);
 	proc_net_fops_create(net, "ip_vs_app", 0, &ip_vs_app_fops);
 	return 0;
 }