[SCSI] scsi_transport_iscsi: Add conn login, kernel to user, event to support offload session login.

Offload drivers like qla4xxx will offload the sending of the login/logout
pdus still, so this patch adds iscsi_conn_login_event which is
used by these types of drivers to notify userspace that the connection
has changed state.

It also adds a iscsi_is_session_online helper so the lld
can query the sessions state field.

Signed-off-by: Manish Rangankar <manish.rangankar@qlogic.com>
Signed-off-by: Lalit Chandivade <lalit.chandivade@qlogic.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/scsi_transport_iscsi.c

@@ -693,6 +693,19 @@ int iscsi_session_chkready(struct iscsi_cls_session *session)
 }
 EXPORT_SYMBOL_GPL(iscsi_session_chkready);
 
+int iscsi_is_session_online(struct iscsi_cls_session *session)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&session->lock, flags);
+	if (session->state == ISCSI_SESSION_LOGGED_IN)
+		ret = 1;
+	spin_unlock_irqrestore(&session->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iscsi_is_session_online);
+
 static void iscsi_session_release(struct device *dev)
 {
 	struct iscsi_cls_session *session = iscsi_dev_to_session(dev);
@@ -1433,6 +1446,40 @@ void iscsi_conn_error_event(struct iscsi_cls_conn *conn, enum iscsi_err error)
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_error_event);
 
+void iscsi_conn_login_event(struct iscsi_cls_conn *conn,
+			    enum iscsi_conn_state state)
+{
+	struct nlmsghdr *nlh;
+	struct sk_buff  *skb;
+	struct iscsi_uevent *ev;
+	struct iscsi_internal *priv;
+	int len = NLMSG_SPACE(sizeof(*ev));
+
+	priv = iscsi_if_transport_lookup(conn->transport);
+	if (!priv)
+		return;
+
+	skb = alloc_skb(len, GFP_ATOMIC);
+	if (!skb) {
+		iscsi_cls_conn_printk(KERN_ERR, conn, "gracefully ignored "
+				      "conn login (%d)\n", state);
+		return;
+	}
+
+	nlh = __nlmsg_put(skb, 0, 0, 0, (len - sizeof(*nlh)), 0);
+	ev = NLMSG_DATA(nlh);
+	ev->transport_handle = iscsi_handle(conn->transport);
+	ev->type = ISCSI_KEVENT_CONN_LOGIN_STATE;
+	ev->r.conn_login.state = state;
+	ev->r.conn_login.cid = conn->cid;
+	ev->r.conn_login.sid = iscsi_conn_get_sid(conn);
+	iscsi_multicast_skb(skb, ISCSI_NL_GRP_ISCSID, GFP_ATOMIC);
+
+	iscsi_cls_conn_printk(KERN_INFO, conn, "detected conn login (%d)\n",
+			      state);
+}
+EXPORT_SYMBOL_GPL(iscsi_conn_login_event);
+
 static int
 iscsi_if_send_reply(uint32_t group, int seq, int type, int done, int multi,
 		    void *payload, int size)

include/scsi/iscsi_if.h

@@ -71,6 +71,7 @@ enum iscsi_uevent_e {
 
 	ISCSI_KEVENT_PATH_REQ		= KEVENT_BASE + 7,
 	ISCSI_KEVENT_IF_DOWN		= KEVENT_BASE + 8,
+	ISCSI_KEVENT_CONN_LOGIN_STATE   = KEVENT_BASE + 9,
 };
 
 enum iscsi_tgt_dscvr {
@@ -198,6 +199,11 @@ struct iscsi_uevent {
 			uint32_t	cid;
 			uint64_t	recv_handle;
 		} recv_req;
+		struct msg_conn_login {
+			uint32_t        sid;
+			uint32_t        cid;
+			uint32_t        state; /* enum iscsi_conn_state */
+		} conn_login;
 		struct msg_conn_error {
 			uint32_t	sid;
 			uint32_t	cid;
@@ -309,6 +315,16 @@ enum iscsi_net_param {
 	ISCSI_NET_PARAM_IFACE_NAME		= 17,
 };
 
+enum iscsi_conn_state {
+	ISCSI_CONN_STATE_FREE,
+	ISCSI_CONN_STATE_XPT_WAIT,
+	ISCSI_CONN_STATE_IN_LOGIN,
+	ISCSI_CONN_STATE_LOGGED_IN,
+	ISCSI_CONN_STATE_IN_LOGOUT,
+	ISCSI_CONN_STATE_LOGOUT_REQUESTED,
+	ISCSI_CONN_STATE_CLEANUP_WAIT,
+};
+
 /*
  * Common error codes
  */
@@ -421,6 +437,7 @@ enum iscsi_host_param {
 #define CAP_DIGEST_OFFLOAD	0x1000	/* offload hdr and data digests */
 #define CAP_PADDING_OFFLOAD	0x2000	/* offload padding insertion, removal,
 					 and verification */
+#define CAP_LOGIN_OFFLOAD	0x4000  /* offload session login */
 
 /*
  * These flags describes reason of stop_conn() call

include/scsi/scsi_transport_iscsi.h

@@ -156,6 +156,8 @@ extern int iscsi_unregister_transport(struct iscsi_transport *tt);
  */
 extern void iscsi_conn_error_event(struct iscsi_cls_conn *conn,
 				   enum iscsi_err error);
+extern void iscsi_conn_login_event(struct iscsi_cls_conn *conn,
+				   enum iscsi_conn_state state);
 extern int iscsi_recv_pdu(struct iscsi_cls_conn *conn, struct iscsi_hdr *hdr,
 			  char *data, uint32_t data_size);
 
@@ -268,6 +270,7 @@ struct iscsi_iface {
 	dev_printk(prefix, &(_cls_conn)->dev, fmt, ##a)
 
 extern int iscsi_session_chkready(struct iscsi_cls_session *session);
+extern int iscsi_is_session_online(struct iscsi_cls_session *session);
 extern struct iscsi_cls_session *iscsi_alloc_session(struct Scsi_Host *shost,
 				struct iscsi_transport *transport, int dd_size);
 extern int iscsi_add_session(struct iscsi_cls_session *session,