net: annotate data-races around sk->sk_lingertime

sk_getsockopt() runs locklessly. This means sk->sk_lingertime
can be read while other threads are changing its value.

Other reads also happen without socket lock being held,
and must be annotated.

Remove preprocessor logic using BITS_PER_LONG, compilers
are smart enough to figure this by themselves.

v2: fixed a clang W=1 (-Wtautological-constant-out-of-range-compare) warning
    (Jakub)

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bluetooth/iso.c

@@ -1475,7 +1475,7 @@ static int iso_sock_release(struct socket *sock)
 
 	iso_sock_close(sk);
 
-	if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
+	if (sock_flag(sk, SOCK_LINGER) && READ_ONCE(sk->sk_lingertime) &&
 	    !(current->flags & PF_EXITING)) {
 		lock_sock(sk);
 		err = bt_sock_wait_state(sk, BT_CLOSED, sk->sk_lingertime);

net/bluetooth/sco.c

@@ -1245,7 +1245,7 @@ static int sco_sock_release(struct socket *sock)
 
 	sco_sock_close(sk);
 
-	if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
+	if (sock_flag(sk, SOCK_LINGER) && READ_ONCE(sk->sk_lingertime) &&
 	    !(current->flags & PF_EXITING)) {
 		lock_sock(sk);
 		err = bt_sock_wait_state(sk, BT_CLOSED, sk->sk_lingertime);

net/core/sock.c

@@ -797,7 +797,7 @@ EXPORT_SYMBOL(sock_set_reuseport);
 void sock_no_linger(struct sock *sk)
 {
 	lock_sock(sk);
-	sk->sk_lingertime = 0;
+	WRITE_ONCE(sk->sk_lingertime, 0);
 	sock_set_flag(sk, SOCK_LINGER);
 	release_sock(sk);
 }
@@ -1230,15 +1230,15 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 			ret = -EFAULT;
 			break;
 		}
-		if (!ling.l_onoff)
+		if (!ling.l_onoff) {
 			sock_reset_flag(sk, SOCK_LINGER);
-		else {
-#if (BITS_PER_LONG == 32)
-			if ((unsigned int)ling.l_linger >= MAX_SCHEDULE_TIMEOUT/HZ)
-				sk->sk_lingertime = MAX_SCHEDULE_TIMEOUT;
+		} else {
+			unsigned long t_sec = ling.l_linger;
+
+			if (t_sec >= MAX_SCHEDULE_TIMEOUT / HZ)
+				WRITE_ONCE(sk->sk_lingertime, MAX_SCHEDULE_TIMEOUT);
 			else
-#endif
-				sk->sk_lingertime = (unsigned int)ling.l_linger * HZ;
+				WRITE_ONCE(sk->sk_lingertime, t_sec * HZ);
 			sock_set_flag(sk, SOCK_LINGER);
 		}
 		break;
@@ -1692,7 +1692,7 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 	case SO_LINGER:
 		lv		= sizeof(v.ling);
 		v.ling.l_onoff	= sock_flag(sk, SOCK_LINGER);
-		v.ling.l_linger	= sk->sk_lingertime / HZ;
+		v.ling.l_linger	= READ_ONCE(sk->sk_lingertime) / HZ;
 		break;
 
 	case SO_BSDCOMPAT:

net/sched/em_meta.c

@@ -502,7 +502,7 @@ META_COLLECTOR(int_sk_lingertime)
 		*err = -1;
 		return;
 	}
-	dst->value = sk->sk_lingertime / HZ;
+	dst->value = READ_ONCE(sk->sk_lingertime) / HZ;
 }
 
 META_COLLECTOR(int_sk_err_qlen)

net/smc/af_smc.c

@@ -1840,7 +1840,7 @@ void smc_close_non_accepted(struct sock *sk)
 	lock_sock(sk);
 	if (!sk->sk_lingertime)
 		/* wait for peer closing */
-		sk->sk_lingertime = SMC_MAX_STREAM_WAIT_TIMEOUT;
+		WRITE_ONCE(sk->sk_lingertime, SMC_MAX_STREAM_WAIT_TIMEOUT);
 	__smc_release(smc);
 	release_sock(sk);
 	sock_put(sk); /* sock_hold above */