[NET]: Replace CONFIG_NET_DEBUG with sysctl.

Covert network warning messages from a compile time to runtime choice.
Removes kernel config option and replaces it with new /proc/sys/net/core/warnings.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 1e75b15..b297120 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -136,6 +136,14 @@
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec
 	},
+	{
+		.ctl_name	= NET_CORE_WARNINGS,
+		.procname	= "warnings",
+		.data		= &net_msg_warn,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec
+	},
 	{ .ctl_name = 0 }
 };
 
diff --git a/net/core/utils.c b/net/core/utils.c
index 07236c1..34f0810 100644
--- a/net/core/utils.c
+++ b/net/core/utils.c
@@ -32,6 +32,8 @@
 
 int net_msg_cost = 5*HZ;
 int net_msg_burst = 10;
+int net_msg_warn = 1;
+EXPORT_SYMBOL(net_msg_warn);
 
 /*
  * All net warning printk()s should be guarded by this function.