[PATCH 1/2] scsi: iscsi: introduce session UNBOUND state to avoid multiple unbind event

[Wenchao Hao <haowenchao@huawei.com>]

Fix the issue of kernel send multiple ISCSI_KEVENT_UNBIND_SESSION event.
If session is in UNBOUND state, do not perform unbind operations anymore,
else unbind session and set session to UNBOUND state.

Reference:https://github.com/open-iscsi/open-iscsi/issues/338

Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
---
 drivers/scsi/scsi_transport_iscsi.c | 19 +++++++++++++++++--
 include/scsi/scsi_transport_iscsi.h |  1 +
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 27951ea05dd4..97a9fee02efa 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -1656,6 +1656,7 @@ static struct {
 	{ ISCSI_SESSION_LOGGED_IN,	"LOGGED_IN" },
 	{ ISCSI_SESSION_FAILED,		"FAILED" },
 	{ ISCSI_SESSION_FREE,		"FREE" },
+	{ ISCSI_SESSION_UNBOUND,	"UNBOUND" },
 };
 
 static const char *iscsi_session_state_name(int state)
@@ -1686,6 +1687,9 @@ int iscsi_session_chkready(struct iscsi_cls_session *session)
 	case ISCSI_SESSION_FREE:
 		err = DID_TRANSPORT_FAILFAST << 16;
 		break;
+	case ISCSI_SESSION_UNBOUND:
+		err = DID_NO_CONNECT << 16;
+		break;
 	default:
 		err = DID_NO_CONNECT << 16;
 		break;
@@ -1838,7 +1842,8 @@ int iscsi_block_scsi_eh(struct scsi_cmnd *cmd)
 
 	spin_lock_irqsave(&session->lock, flags);
 	while (session->state != ISCSI_SESSION_LOGGED_IN) {
-		if (session->state == ISCSI_SESSION_FREE) {
+		if ((session->state == ISCSI_SESSION_FREE) ||
+		    (session->state == ISCSI_SESSION_UNBOUND)) {
 			ret = FAST_IO_FAIL;
 			break;
 		}
@@ -1869,6 +1874,7 @@ static void session_recovery_timedout(struct work_struct *work)
 		break;
 	case ISCSI_SESSION_LOGGED_IN:
 	case ISCSI_SESSION_FREE:
+	case ISCSI_SESSION_UNBOUND:
 		/* we raced with the unblock's flush */
 		spin_unlock_irqrestore(&session->lock, flags);
 		return;
@@ -1957,6 +1963,14 @@ static void __iscsi_unbind_session(struct work_struct *work)
 	unsigned long flags;
 	unsigned int target_id;
 
+	spin_lock_irqsave(&session->lock, flags);
+	if (session->state == ISCSI_SESSION_UNBOUND) {
+		spin_unlock_irqrestore(&session->lock, flags);
+		return;
+	}
+	session->state = ISCSI_SESSION_UNBOUND;
+	spin_unlock_irqrestore(&session->lock, flags);
+
 	ISCSI_DBG_TRANS_SESSION(session, "Unbinding session\n");
 
 	/* Prevent new scans and make sure scanning is not in progress */
@@ -4329,7 +4343,8 @@ store_priv_session_##field(struct device *dev,				\
 	struct iscsi_cls_session *session =				\
 		iscsi_dev_to_session(dev->parent);			\
 	if ((session->state == ISCSI_SESSION_FREE) ||			\
-	    (session->state == ISCSI_SESSION_FAILED))			\
+	    (session->state == ISCSI_SESSION_FAILED) ||			\
+	    (session->state == ISCSI_SESSION_UNBOUND))			\
 		return -EBUSY;						\
 	if (strncmp(buf, "off", 3) == 0) {				\
 		session->field = -1;					\
diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index 38e4a67f5922..80149643cbcd 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -232,6 +232,7 @@ enum {
 	ISCSI_SESSION_LOGGED_IN,
 	ISCSI_SESSION_FAILED,
 	ISCSI_SESSION_FREE,
+	ISCSI_SESSION_UNBOUND,
 };
 
 #define ISCSI_MAX_TARGET -1
-- 
2.32.0