releases/3.4.20/0044-libceph-start-tracking-connection-socket-state.patch

From 1dc8c9af19ebb0486a3d573579358c4a3f918bb0 Mon Sep 17 00:00:00 2001
From: Alex Elder <elder@inktank.com>
Date: Tue, 22 May 2012 22:15:49 -0500
Subject: libceph: start tracking connection socket state

From: Alex Elder <elder@inktank.com>

(cherry picked from commit ce2c8903e76e690846a00a0284e4bd9ee954d680)

Start explicitly keeping track of the state of a ceph connection's
socket, separate from the state of the connection itself.  Create
placeholder functions to encapsulate the state transitions.

    --------
    | NEW* |  transient initial state
    --------
        | con_sock_state_init()
        v
    ----------
    | CLOSED |  initialized, but no socket (and no
    ----------  TCP connection)
     ^      \
     |       \ con_sock_state_connecting()
     |        ----------------------
     |                              \
     + con_sock_state_closed()       \
     |\                               \
     | \                               \
     |  -----------                     \
     |  | CLOSING |  socket event;       \
     |  -----------  await close          \
     |       ^                            |
     |       |                            |
     |       + con_sock_state_closing()   |
     |      / \                           |
     |     /   ---------------            |
     |    /                   \           v
     |   /                    --------------
     |  /    -----------------| CONNECTING |  socket created, TCP
     |  |   /                 --------------  connect initiated
     |  |   | con_sock_state_connected()
     |  |   v
    -------------
    | CONNECTED |  TCP connection established
    -------------

Make the socket state an atomic variable, reinforcing that it's a
distinct transtion with no possible "intermediate/both" states.
This is almost certainly overkill at this point, though the
transitions into CONNECTED and CLOSING state do get called via
socket callback (the rest of the transitions occur with the
connection mutex held).  We can back out the atomicity later.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil<sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/ceph/messenger.h |    8 +++--
 net/ceph/messenger.c           |   64 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 2 deletions(-)

--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -137,14 +137,18 @@ struct ceph_connection {
 	const struct ceph_connection_operations *ops;
 
 	struct ceph_messenger *msgr;
+
+	atomic_t sock_state;
 	struct socket *sock;
+	struct ceph_entity_addr peer_addr; /* peer address */
+	struct ceph_entity_addr peer_addr_for_me;
+
 	unsigned long flags;
 	unsigned long state;
 	const char *error_msg;  /* error message, if any */
 
-	struct ceph_entity_addr peer_addr; /* peer address */
 	struct ceph_entity_name peer_name; /* peer name */
-	struct ceph_entity_addr peer_addr_for_me;
+
 	unsigned peer_features;
 	u32 connect_seq;      /* identify the most recent connection
 				 attempt for this connection, client */
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -29,6 +29,14 @@
  * the sender.
  */
 
+/* State values for ceph_connection->sock_state; NEW is assumed to be 0 */
+
+#define CON_SOCK_STATE_NEW		0	/* -> CLOSED */
+#define CON_SOCK_STATE_CLOSED		1	/* -> CONNECTING */
+#define CON_SOCK_STATE_CONNECTING	2	/* -> CONNECTED or -> CLOSING */
+#define CON_SOCK_STATE_CONNECTED	3	/* -> CLOSING or -> CLOSED */
+#define CON_SOCK_STATE_CLOSING		4	/* -> CLOSED */
+
 /* static tag bytes (protocol control messages) */
 static char tag_msg = CEPH_MSGR_TAG_MSG;
 static char tag_ack = CEPH_MSGR_TAG_ACK;
@@ -147,6 +155,55 @@ void ceph_msgr_flush(void)
 }
 EXPORT_SYMBOL(ceph_msgr_flush);
 
+/* Connection socket state transition functions */
+
+static void con_sock_state_init(struct ceph_connection *con)
+{
+	int old_state;
+
+	old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CLOSED);
+	if (WARN_ON(old_state != CON_SOCK_STATE_NEW))
+		printk("%s: unexpected old state %d\n", __func__, old_state);
+}
+
+static void con_sock_state_connecting(struct ceph_connection *con)
+{
+	int old_state;
+
+	old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CONNECTING);
+	if (WARN_ON(old_state != CON_SOCK_STATE_CLOSED))
+		printk("%s: unexpected old state %d\n", __func__, old_state);
+}
+
+static void con_sock_state_connected(struct ceph_connection *con)
+{
+	int old_state;
+
+	old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CONNECTED);
+	if (WARN_ON(old_state != CON_SOCK_STATE_CONNECTING))
+		printk("%s: unexpected old state %d\n", __func__, old_state);
+}
+
+static void con_sock_state_closing(struct ceph_connection *con)
+{
+	int old_state;
+
+	old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CLOSING);
+	if (WARN_ON(old_state != CON_SOCK_STATE_CONNECTING &&
+			old_state != CON_SOCK_STATE_CONNECTED &&
+			old_state != CON_SOCK_STATE_CLOSING))
+		printk("%s: unexpected old state %d\n", __func__, old_state);
+}
+
+static void con_sock_state_closed(struct ceph_connection *con)
+{
+	int old_state;
+
+	old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CLOSED);
+	if (WARN_ON(old_state != CON_SOCK_STATE_CONNECTED &&
+			old_state != CON_SOCK_STATE_CLOSING))
+		printk("%s: unexpected old state %d\n", __func__, old_state);
+}
 
 /*
  * socket callback functions
@@ -203,6 +260,7 @@ static void ceph_sock_state_change(struc
 		dout("%s TCP_CLOSE\n", __func__);
 	case TCP_CLOSE_WAIT:
 		dout("%s TCP_CLOSE_WAIT\n", __func__);
+		con_sock_state_closing(con);
 		if (test_and_set_bit(SOCK_CLOSED, &con->flags) == 0) {
 			if (test_bit(CONNECTING, &con->state))
 				con->error_msg = "connection failed";
@@ -213,6 +271,7 @@ static void ceph_sock_state_change(struc
 		break;
 	case TCP_ESTABLISHED:
 		dout("%s TCP_ESTABLISHED\n", __func__);
+		con_sock_state_connected(con);
 		queue_con(con);
 		break;
 	default:	/* Everything else is uninteresting */
@@ -277,6 +336,7 @@ static int ceph_tcp_connect(struct ceph_
 		return ret;
 	}
 	con->sock = sock;
+	con_sock_state_connecting(con);
 
 	return 0;
 }
@@ -343,6 +403,7 @@ static int con_close_socket(struct ceph_
 	sock_release(con->sock);
 	con->sock = NULL;
 	clear_bit(SOCK_CLOSED, &con->state);
+	con_sock_state_closed(con);
 	return rc;
 }
 
@@ -462,6 +523,9 @@ void ceph_con_init(struct ceph_messenger
 	memset(con, 0, sizeof(*con));
 	atomic_set(&con->nref, 1);
 	con->msgr = msgr;
+
+	con_sock_state_init(con);
+
 	mutex_init(&con->mutex);
 	INIT_LIST_HEAD(&con->out_queue);
 	INIT_LIST_HEAD(&con->out_sent);