Merge tag 'kvm-arm-for-4.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-next

KVM/ARM changes for Linux v4.5

- Complete rewrite of the arm64 world switch in C, hopefully
  paving the way for more sharing with the 32bit code, better
  maintainability and easier integration of new features.
  Also smaller and slightly faster in some cases...
- Support for 16bit VM identifiers
- Various cleanups

1 files changed, 231 insertions, 37 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 955ec152cb71..45aebd966978 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -326,6 +326,118 @@ found:
 	return s;
 }
 
+/* Support code for asymmetrically connected dgram sockets
+ *
+ * If a datagram socket is connected to a socket not itself connected
+ * to the first socket (eg, /dev/log), clients may only enqueue more
+ * messages if the present receive queue of the server socket is not
+ * "too large". This means there's a second writeability condition
+ * poll and sendmsg need to test. The dgram recv code will do a wake
+ * up on the peer_wait wait queue of a socket upon reception of a
+ * datagram which needs to be propagated to sleeping would-be writers
+ * since these might not have sent anything so far. This can't be
+ * accomplished via poll_wait because the lifetime of the server
+ * socket might be less than that of its clients if these break their
+ * association with it or if the server socket is closed while clients
+ * are still connected to it and there's no way to inform "a polling
+ * implementation" that it should let go of a certain wait queue
+ *
+ * In order to propagate a wake up, a wait_queue_t of the client
+ * socket is enqueued on the peer_wait queue of the server socket
+ * whose wake function does a wake_up on the ordinary client socket
+ * wait queue. This connection is established whenever a write (or
+ * poll for write) hit the flow control condition and broken when the
+ * association to the server socket is dissolved or after a wake up
+ * was relayed.
+ */
+
+static int unix_dgram_peer_wake_relay(wait_queue_t *q, unsigned mode, int flags,
+				      void *key)
+{
+	struct unix_sock *u;
+	wait_queue_head_t *u_sleep;
+
+	u = container_of(q, struct unix_sock, peer_wake);
+
+	__remove_wait_queue(&unix_sk(u->peer_wake.private)->peer_wait,
+			    q);
+	u->peer_wake.private = NULL;
+
+	/* relaying can only happen while the wq still exists */
+	u_sleep = sk_sleep(&u->sk);
+	if (u_sleep)
+		wake_up_interruptible_poll(u_sleep, key);
+
+	return 0;
+}
+
+static int unix_dgram_peer_wake_connect(struct sock *sk, struct sock *other)
+{
+	struct unix_sock *u, *u_other;
+	int rc;
+
+	u = unix_sk(sk);
+	u_other = unix_sk(other);
+	rc = 0;
+	spin_lock(&u_other->peer_wait.lock);
+
+	if (!u->peer_wake.private) {
+		u->peer_wake.private = other;
+		__add_wait_queue(&u_other->peer_wait, &u->peer_wake);
+
+		rc = 1;
+	}
+
+	spin_unlock(&u_other->peer_wait.lock);
+	return rc;
+}
+
+static void unix_dgram_peer_wake_disconnect(struct sock *sk,
+					    struct sock *other)
+{
+	struct unix_sock *u, *u_other;
+
+	u = unix_sk(sk);
+	u_other = unix_sk(other);
+	spin_lock(&u_other->peer_wait.lock);
+
+	if (u->peer_wake.private == other) {
+		__remove_wait_queue(&u_other->peer_wait, &u->peer_wake);
+		u->peer_wake.private = NULL;
+	}
+
+	spin_unlock(&u_other->peer_wait.lock);
+}
+
+static void unix_dgram_peer_wake_disconnect_wakeup(struct sock *sk,
+						   struct sock *other)
+{
+	unix_dgram_peer_wake_disconnect(sk, other);
+	wake_up_interruptible_poll(sk_sleep(sk),
+				   POLLOUT |
+				   POLLWRNORM |
+				   POLLWRBAND);
+}
+
+/* preconditions:
+ *	- unix_peer(sk) == other
+ *	- association is stable
+ */
+static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other)
+{
+	int connected;
+
+	connected = unix_dgram_peer_wake_connect(sk, other);
+
+	if (unix_recvq_full(other))
+		return 1;
+
+	if (connected)
+		unix_dgram_peer_wake_disconnect(sk, other);
+
+	return 0;
+}
+
 static int unix_writable(const struct sock *sk)
 {
 	return sk->sk_state != TCP_LISTEN &&
@@ -431,6 +543,8 @@ static void unix_release_sock(struct sock *sk, int embrion)
 			skpair->sk_state_change(skpair);
 			sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);
 		}
+
+		unix_dgram_peer_wake_disconnect(sk, skpair);
 		sock_put(skpair); /* It may now die */
 		unix_peer(sk) = NULL;
 	}
@@ -666,6 +780,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
 	INIT_LIST_HEAD(&u->link);
 	mutex_init(&u->readlock); /* single task reading lock */
 	init_waitqueue_head(&u->peer_wait);
+	init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);
 	unix_insert_socket(unix_sockets_unbound(sk), sk);
 out:
 	if (sk == NULL)
@@ -1033,6 +1148,8 @@ restart:
 	if (unix_peer(sk)) {
 		struct sock *old_peer = unix_peer(sk);
 		unix_peer(sk) = other;
+		unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer);
+
 		unix_state_double_unlock(sk, other);
 
 		if (other != old_peer)
@@ -1434,6 +1551,14 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen
 	return err;
 }
 
+static bool unix_passcred_enabled(const struct socket *sock,
+				  const struct sock *other)
+{
+	return test_bit(SOCK_PASSCRED, &sock->flags) ||
+	       !other->sk_socket ||
+	       test_bit(SOCK_PASSCRED, &other->sk_socket->flags);
+}
+
 /*
  * Some apps rely on write() giving SCM_CREDENTIALS
  * We include credentials if source or destination socket
@@ -1444,14 +1569,41 @@ static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
 {
 	if (UNIXCB(skb).pid)
 		return;
-	if (test_bit(SOCK_PASSCRED, &sock->flags) ||
-	    !other->sk_socket ||
-	    test_bit(SOCK_PASSCRED, &other->sk_socket->flags)) {
+	if (unix_passcred_enabled(sock, other)) {
 		UNIXCB(skb).pid  = get_pid(task_tgid(current));
 		current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);
 	}
 }
 
+static int maybe_init_creds(struct scm_cookie *scm,
+			    struct socket *socket,
+			    const struct sock *other)
+{
+	int err;
+	struct msghdr msg = { .msg_controllen = 0 };
+
+	err = scm_send(socket, &msg, scm, false);
+	if (err)
+		return err;
+
+	if (unix_passcred_enabled(socket, other)) {
+		scm->pid = get_pid(task_tgid(current));
+		current_uid_gid(&scm->creds.uid, &scm->creds.gid);
+	}
+	return err;
+}
+
+static bool unix_skb_scm_eq(struct sk_buff *skb,
+			    struct scm_cookie *scm)
+{
+	const struct unix_skb_parms *u = &UNIXCB(skb);
+
+	return u->pid == scm->pid &&
+	       uid_eq(u->uid, scm->creds.uid) &&
+	       gid_eq(u->gid, scm->creds.gid) &&
+	       unix_secdata_eq(scm, skb);
+}
+
 /*
  *	Send AF_UNIX data.
  */
@@ -1472,6 +1624,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 	struct scm_cookie scm;
 	int max_level;
 	int data_len = 0;
+	int sk_locked;
 
 	wait_for_unix_gc();
 	err = scm_send(sock, msg, &scm, false);
@@ -1550,12 +1703,14 @@ restart:
 		goto out_free;
 	}
 
+	sk_locked = 0;
 	unix_state_lock(other);
+restart_locked:
 	err = -EPERM;
 	if (!unix_may_send(sk, other))
 		goto out_unlock;
 
-	if (sock_flag(other, SOCK_DEAD)) {
+	if (unlikely(sock_flag(other, SOCK_DEAD))) {
 		/*
 		 *	Check with 1003.1g - what should
 		 *	datagram error
@@ -1563,10 +1718,14 @@ restart:
 		unix_state_unlock(other);
 		sock_put(other);
 
+		if (!sk_locked)
+			unix_state_lock(sk);
+
 		err = 0;
-		unix_state_lock(sk);
 		if (unix_peer(sk) == other) {
 			unix_peer(sk) = NULL;
+			unix_dgram_peer_wake_disconnect_wakeup(sk, other);
+
 			unix_state_unlock(sk);
 
 			unix_dgram_disconnected(sk, other);
@@ -1592,21 +1751,38 @@ restart:
 			goto out_unlock;
 	}
 
-	if (unix_peer(other) != sk && unix_recvq_full(other)) {
-		if (!timeo) {
-			err = -EAGAIN;
-			goto out_unlock;
+	if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) {
+		if (timeo) {
+			timeo = unix_wait_for_peer(other, timeo);
+
+			err = sock_intr_errno(timeo);
+			if (signal_pending(current))
+				goto out_free;
+
+			goto restart;
 		}
 
-		timeo = unix_wait_for_peer(other, timeo);
+		if (!sk_locked) {
+			unix_state_unlock(other);
+			unix_state_double_lock(sk, other);
+		}
 
-		err = sock_intr_errno(timeo);
-		if (signal_pending(current))
-			goto out_free;
+		if (unix_peer(sk) != other ||
+		    unix_dgram_peer_wake_me(sk, other)) {
+			err = -EAGAIN;
+			sk_locked = 1;
+			goto out_unlock;
+		}
 
-		goto restart;
+		if (!sk_locked) {
+			sk_locked = 1;
+			goto restart_locked;
+		}
 	}
 
+	if (unlikely(sk_locked))
+		unix_state_unlock(sk);
+
 	if (sock_flag(other, SOCK_RCVTSTAMP))
 		__net_timestamp(skb);
 	maybe_add_creds(skb, sock, other);
@@ -1620,6 +1796,8 @@ restart:
 	return len;
 
 out_unlock:
+	if (sk_locked)
+		unix_state_unlock(sk);
 	unix_state_unlock(other);
 out_free:
 	kfree_skb(skb);
@@ -1741,8 +1919,10 @@ out_err:
 static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,
 				    int offset, size_t size, int flags)
 {
-	int err = 0;
-	bool send_sigpipe = true;
+	int err;
+	bool send_sigpipe = false;
+	bool init_scm = true;
+	struct scm_cookie scm;
 	struct sock *other, *sk = socket->sk;
 	struct sk_buff *skb, *newskb = NULL, *tail = NULL;
 
@@ -1760,7 +1940,7 @@ alloc_skb:
 		newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT,
 					      &err, 0);
 		if (!newskb)
-			return err;
+			goto err;
 	}
 
 	/* we must acquire readlock as we modify already present
@@ -1769,12 +1949,12 @@ alloc_skb:
 	err = mutex_lock_interruptible(&unix_sk(other)->readlock);
 	if (err) {
 		err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS;
-		send_sigpipe = false;
 		goto err;
 	}
 
 	if (sk->sk_shutdown & SEND_SHUTDOWN) {
 		err = -EPIPE;
+		send_sigpipe = true;
 		goto err_unlock;
 	}
 
@@ -1783,17 +1963,27 @@ alloc_skb:
 	if (sock_flag(other, SOCK_DEAD) ||
 	    other->sk_shutdown & RCV_SHUTDOWN) {
 		err = -EPIPE;
+		send_sigpipe = true;
 		goto err_state_unlock;
 	}
 
+	if (init_scm) {
+		err = maybe_init_creds(&scm, socket, other);
+		if (err)
+			goto err_state_unlock;
+		init_scm = false;
+	}
+
 	skb = skb_peek_tail(&other->sk_receive_queue);
 	if (tail && tail == skb) {
 		skb = newskb;
-	} else if (!skb) {
-		if (newskb)
+	} else if (!skb || !unix_skb_scm_eq(skb, &scm)) {
+		if (newskb) {
 			skb = newskb;
-		else
+		} else {
+			tail = skb;
 			goto alloc_skb;
+		}
 	} else if (newskb) {
 		/* this is fast path, we don't necessarily need to
 		 * call to kfree_skb even though with newskb == NULL
@@ -1814,6 +2004,9 @@ alloc_skb:
 	atomic_add(size, &sk->sk_wmem_alloc);
 
 	if (newskb) {
+		err = unix_scm_to_skb(&scm, skb, false);
+		if (err)
+			goto err_state_unlock;
 		spin_lock(&other->sk_receive_queue.lock);
 		__skb_queue_tail(&other->sk_receive_queue, newskb);
 		spin_unlock(&other->sk_receive_queue.lock);
@@ -1823,7 +2016,7 @@ alloc_skb:
 	mutex_unlock(&unix_sk(other)->readlock);
 
 	other->sk_data_ready(other);
-
+	scm_destroy(&scm);
 	return size;
 
 err_state_unlock:
@@ -1834,6 +2027,8 @@ err:
 	kfree_skb(newskb);
 	if (send_sigpipe && !(flags & MSG_NOSIGNAL))
 		send_sig(SIGPIPE, current, 0);
+	if (!init_scm)
+		scm_destroy(&scm);
 	return err;
 }
 
@@ -1996,7 +2191,7 @@ static long unix_stream_data_wait(struct sock *sk, long timeo,
 		    !timeo)
 			break;
 
-		set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
+		sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 		unix_state_unlock(sk);
 		timeo = freezable_schedule_timeout(timeo);
 		unix_state_lock(sk);
@@ -2004,7 +2199,7 @@ static long unix_stream_data_wait(struct sock *sk, long timeo,
 		if (sock_flag(sk, SOCK_DEAD))
 			break;
 
-		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
+		sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 	}
 
 	finish_wait(sk_sleep(sk), &wait);
@@ -2137,10 +2332,7 @@ unlock:
 
 		if (check_creds) {
 			/* Never glue messages from different writers */
-			if ((UNIXCB(skb).pid  != scm.pid) ||
-			    !uid_eq(UNIXCB(skb).uid, scm.creds.uid) ||
-			    !gid_eq(UNIXCB(skb).gid, scm.creds.gid) ||
-			    !unix_secdata_eq(&scm, skb))
+			if (!unix_skb_scm_eq(skb, &scm))
 				break;
 		} else if (test_bit(SOCK_PASSCRED, &sock->flags)) {
 			/* Copy credentials */
@@ -2476,20 +2668,22 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
 		return mask;
 
 	writable = unix_writable(sk);
-	other = unix_peer_get(sk);
-	if (other) {
-		if (unix_peer(other) != sk) {
-			sock_poll_wait(file, &unix_sk(other)->peer_wait, wait);
-			if (unix_recvq_full(other))
-				writable = 0;
-		}
-		sock_put(other);
+	if (writable) {
+		unix_state_lock(sk);
+
+		other = unix_peer(sk);
+		if (other && unix_peer(other) != sk &&
+		    unix_recvq_full(other) &&
+		    unix_dgram_peer_wake_me(sk, other))
+			writable = 0;
+
+		unix_state_unlock(sk);
 	}
 
 	if (writable)
 		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
 	else
-		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
+		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 
 	return mask;
 }