sock: add net to prot->enter_memory_pressure callback

The tcp_enter_memory_pressure calls NET_INC_STATS, but doesn't
have where to get the net from.

I decided to add a sk argument, not the net itself, only to factor
all the required sock_net(sk) calls inside the enter_memory_pressure 
callback itself.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -565,7 +565,7 @@ struct proto {
 #endif
 
 	/* Memory pressure */
-	void			(*enter_memory_pressure)(void);
+	void			(*enter_memory_pressure)(struct sock *sk);
 	atomic_t		*memory_allocated;	/* Current allocated memory. */
 	atomic_t		*sockets_allocated;	/* Current number of sockets. */
 	/*
@@ -1210,7 +1210,7 @@ static inline struct page *sk_stream_alloc_page(struct sock *sk)
 
 	page = alloc_pages(sk->sk_allocation, 0);
 	if (!page) {
-		sk->sk_prot->enter_memory_pressure();
+		sk->sk_prot->enter_memory_pressure(sk);
 		sk_stream_moderate_sndbuf(sk);
 	}
 	return page;

include/net/tcp.h

@@ -975,7 +975,7 @@ static inline void tcp_openreq_init(struct request_sock *req,
 	ireq->rmt_port = tcp_hdr(skb)->source;
 }
 
-extern void tcp_enter_memory_pressure(void);
+extern void tcp_enter_memory_pressure(struct sock *sk);
 
 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
 {

net/core/sock.c

@@ -1442,7 +1442,7 @@ int __sk_mem_schedule(struct sock *sk, int size, int kind)
 	/* Under pressure. */
 	if (allocated > prot->sysctl_mem[1])
 		if (prot->enter_memory_pressure)
-			prot->enter_memory_pressure();
+			prot->enter_memory_pressure(sk);
 
 	/* Over hard limit. */
 	if (allocated > prot->sysctl_mem[2])

net/decnet/af_decnet.c

@@ -451,7 +451,7 @@ static void dn_destruct(struct sock *sk)
 
 static int dn_memory_pressure;
 
-static void dn_enter_memory_pressure(void)
+static void dn_enter_memory_pressure(struct sock *sk)
 {
 	if (!dn_memory_pressure) {
 		dn_memory_pressure = 1;

net/ipv4/tcp.c

@@ -316,7 +316,7 @@ int tcp_memory_pressure __read_mostly;
 
 EXPORT_SYMBOL(tcp_memory_pressure);
 
-void tcp_enter_memory_pressure(void)
+void tcp_enter_memory_pressure(struct sock *sk)
 {
 	if (!tcp_memory_pressure) {
 		NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
@@ -649,7 +649,7 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
 		}
 		__kfree_skb(skb);
 	} else {
-		sk->sk_prot->enter_memory_pressure();
+		sk->sk_prot->enter_memory_pressure(sk);
 		sk_stream_moderate_sndbuf(sk);
 	}
 	return NULL;

net/sctp/socket.c

@@ -116,7 +116,7 @@ static int sctp_memory_pressure;
 static atomic_t sctp_memory_allocated;
 static atomic_t sctp_sockets_allocated;
 
-static void sctp_enter_memory_pressure(void)
+static void sctp_enter_memory_pressure(struct sock *sk)
 {
 	sctp_memory_pressure = 1;
 }