[SCSI] iscsi class, libiscsi: add iscsi sysfs session state file

This adds a iscsi session state file which exports the session
state for both software and hardware iscsi. It also hooks libiscsi
in.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 104 insertions, 3 deletions

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 0d7b4e7..f876b0a 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -30,7 +30,7 @@
 #include <scsi/scsi_transport_iscsi.h>
 #include <scsi/iscsi_if.h>
 
-#define ISCSI_SESSION_ATTRS 18
+#define ISCSI_SESSION_ATTRS 19
 #define ISCSI_CONN_ATTRS 11
 #define ISCSI_HOST_ATTRS 4
 #define ISCSI_TRANSPORT_VERSION "2.0-867"
@@ -221,6 +221,54 @@ static struct iscsi_cls_conn *iscsi_conn_lookup(uint32_t sid, uint32_t cid)
  * The following functions can be used by LLDs that allocate
  * their own scsi_hosts or by software iscsi LLDs
  */
+static struct {
+	int value;
+	char *name;
+} iscsi_session_state_names[] = {
+	{ ISCSI_SESSION_LOGGED_IN,	"LOGGED_IN" },
+	{ ISCSI_SESSION_FAILED,		"FAILED" },
+	{ ISCSI_SESSION_FREE,		"FREE" },
+};
+
+const char *iscsi_session_state_name(int state)
+{
+	int i;
+	char *name = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(iscsi_session_state_names); i++) {
+		if (iscsi_session_state_names[i].value == state) {
+			name = iscsi_session_state_names[i].name;
+			break;
+		}
+	}
+	return name;
+}
+
+int iscsi_session_chkready(struct iscsi_cls_session *session)
+{
+	unsigned long flags;
+	int err;
+
+	spin_lock_irqsave(&session->lock, flags);
+	switch (session->state) {
+	case ISCSI_SESSION_LOGGED_IN:
+		err = 0;
+		break;
+	case ISCSI_SESSION_FAILED:
+		err = DID_IMM_RETRY << 16;
+		break;
+	case ISCSI_SESSION_FREE:
+		err = DID_NO_CONNECT << 16;
+		break;
+	default:
+		err = DID_NO_CONNECT << 16;
+		break;
+	}
+	spin_unlock_irqrestore(&session->lock, flags);
+	return err;
+}
+EXPORT_SYMBOL_GPL(iscsi_session_chkready);
+
 static void iscsi_session_release(struct device *dev)
 {
 	struct iscsi_cls_session *session = iscsi_dev_to_session(dev);
@@ -259,26 +307,57 @@ static void session_recovery_timedout(struct work_struct *work)
 	struct iscsi_cls_session *session =
 		container_of(work, struct iscsi_cls_session,
 			     recovery_work.work);
+	unsigned long flags;
 
 	dev_printk(KERN_INFO, &session->dev, "iscsi: session recovery timed "
 		  "out after %d secs\n", session->recovery_tmo);
 
+	spin_lock_irqsave(&session->lock, flags);
+	switch (session->state) {
+	case ISCSI_SESSION_FAILED:
+		session->state = ISCSI_SESSION_FREE;
+		break;
+	case ISCSI_SESSION_LOGGED_IN:
+	case ISCSI_SESSION_FREE:
+		/* we raced with the unblock's flush */
+		spin_unlock_irqrestore(&session->lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&session->lock, flags);
+
 	if (session->transport->session_recovery_timedout)
 		session->transport->session_recovery_timedout(session);
 
 	scsi_target_unblock(&session->dev);
 }
 
-void iscsi_unblock_session(struct iscsi_cls_session *session)
+void __iscsi_unblock_session(struct iscsi_cls_session *session)
 {
 	if (!cancel_delayed_work(&session->recovery_work))
 		flush_workqueue(iscsi_eh_timer_workq);
 	scsi_target_unblock(&session->dev);
 }
+
+void iscsi_unblock_session(struct iscsi_cls_session *session)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&session->lock, flags);
+	session->state = ISCSI_SESSION_LOGGED_IN;
+	spin_unlock_irqrestore(&session->lock, flags);
+
+	__iscsi_unblock_session(session);
+}
 EXPORT_SYMBOL_GPL(iscsi_unblock_session);
 
 void iscsi_block_session(struct iscsi_cls_session *session)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&session->lock, flags);
+	session->state = ISCSI_SESSION_FAILED;
+	spin_unlock_irqrestore(&session->lock, flags);
+
 	scsi_target_block(&session->dev);
 	queue_delayed_work(iscsi_eh_timer_workq, &session->recovery_work,
 			   session->recovery_tmo * HZ);
@@ -327,10 +406,12 @@ iscsi_alloc_session(struct Scsi_Host *shost,
 
 	session->transport = transport;
 	session->recovery_tmo = 120;
+	session->state = ISCSI_SESSION_FREE;
 	INIT_DELAYED_WORK(&session->recovery_work, session_recovery_timedout);
 	INIT_LIST_HEAD(&session->host_list);
 	INIT_LIST_HEAD(&session->sess_list);
 	INIT_WORK(&session->unbind_work, __iscsi_unbind_session);
+	spin_lock_init(&session->lock);
 
 	/* this is released in the dev's release function */
 	scsi_host_get(shost);
@@ -444,7 +525,10 @@ void iscsi_remove_session(struct iscsi_cls_session *session)
 	 * If we are blocked let commands flow again. The lld or iscsi
 	 * layer should set up the queuecommand to fail commands.
 	 */
-	iscsi_unblock_session(session);
+	spin_lock_irqsave(&session->lock, flags);
+	session->state = ISCSI_SESSION_FREE;
+	spin_unlock_irqrestore(&session->lock, flags);
+	__iscsi_unblock_session(session);
 	iscsi_unbind_session(session);
 	/*
 	 * If the session dropped while removing devices then we need to make
@@ -661,16 +745,23 @@ EXPORT_SYMBOL_GPL(iscsi_recv_pdu);
 
 void iscsi_conn_error(struct iscsi_cls_conn *conn, enum iscsi_err error)
 {
+	struct iscsi_cls_session *session = iscsi_conn_to_session(conn);
 	struct nlmsghdr	*nlh;
 	struct sk_buff	*skb;
 	struct iscsi_uevent *ev;
 	struct iscsi_internal *priv;
 	int len = NLMSG_SPACE(sizeof(*ev));
+	unsigned long flags;
 
 	priv = iscsi_if_transport_lookup(conn->transport);
 	if (!priv)
 		return;
 
+	spin_lock_irqsave(&session->lock, flags);
+	if (session->state == ISCSI_SESSION_LOGGED_IN)
+		session->state = ISCSI_SESSION_FAILED;
+	spin_unlock_irqrestore(&session->lock, flags);
+
 	skb = alloc_skb(len, GFP_ATOMIC);
 	if (!skb) {
 		dev_printk(KERN_ERR, &conn->dev, "iscsi: gracefully ignored "
@@ -1246,6 +1337,15 @@ iscsi_session_attr(fast_abort, ISCSI_PARAM_FAST_ABORT, 0);
 iscsi_session_attr(abort_tmo, ISCSI_PARAM_ABORT_TMO, 0);
 iscsi_session_attr(lu_reset_tmo, ISCSI_PARAM_LU_RESET_TMO, 0);
 
+static ssize_t
+show_priv_session_state(struct class_device *cdev, char *buf)
+{
+	struct iscsi_cls_session *session = iscsi_cdev_to_session(cdev);
+	return sprintf(buf, "%s\n", iscsi_session_state_name(session->state));
+}
+static ISCSI_CLASS_ATTR(priv_sess, state, S_IRUGO, show_priv_session_state,
+			NULL);
+
 #define iscsi_priv_session_attr_show(field, format)			\
 static ssize_t								\
 show_priv_session_##field(struct class_device *cdev, char *buf)		\
@@ -1472,6 +1572,7 @@ iscsi_register_transport(struct iscsi_transport *tt)
 	SETUP_SESSION_RD_ATTR(abort_tmo, ISCSI_ABORT_TMO);
 	SETUP_SESSION_RD_ATTR(lu_reset_tmo,ISCSI_LU_RESET_TMO);
 	SETUP_PRIV_SESSION_RD_ATTR(recovery_tmo);
+	SETUP_PRIV_SESSION_RD_ATTR(state);
 
 	BUG_ON(count > ISCSI_SESSION_ATTRS);
 	priv->session_attrs[count] = NULL;