[TWSK]: Grab the module refcount for timewait sockets

This is required to avoid unloading a module that has active timewait
sockets, such as DCCP.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_timewait_sock.h

@@ -19,6 +19,7 @@
 
 #include <linux/ip.h>
 #include <linux/list.h>
+#include <linux/module.h>
 #include <linux/timer.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
@@ -193,11 +194,13 @@ static inline u32 inet_rcv_saddr(const struct sock *sk)
 static inline void inet_twsk_put(struct inet_timewait_sock *tw)
 {
 	if (atomic_dec_and_test(&tw->tw_refcnt)) {
+		struct module *owner = tw->tw_prot->owner;
 #ifdef SOCK_REFCNT_DEBUG
 		printk(KERN_DEBUG "%s timewait_sock %p released\n",
 		       tw->tw_prot->name, tw);
 #endif
 		kmem_cache_free(tw->tw_prot->twsk_slab, tw);
+		module_put(owner);
 	}
 }
 

net/ipv4/inet_timewait_sock.c

@@ -111,6 +111,7 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int stat
 		tw->tw_prot	    = sk->sk_prot_creator;
 		atomic_set(&tw->tw_refcnt, 1);
 		inet_twsk_dead_node_init(tw);
+		__module_get(tw->tw_prot->owner);
 	}
 
 	return tw;