scsi: iscsi: Fix NOP handling during conn recovery

If a offload driver doesn't use the xmit workqueue, then when we are doing
ep_disconnect libiscsi can still inject PDUs to the driver. This adds a
check for if the connection is bound before trying to inject PDUs.

Link: https://lore.kernel.org/r/20220408001314.5014-9-michael.christie@oracle.com
Tested-by: Manish Rangankar <mrangankar@marvell.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Chris Leech <cleech@redhat.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libiscsi.c

@@ -678,7 +678,8 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 	struct iscsi_task *task;
 	itt_t itt;
 
-	if (session->state == ISCSI_STATE_TERMINATE)
+	if (session->state == ISCSI_STATE_TERMINATE ||
+	    !test_bit(ISCSI_CONN_FLAG_BOUND, &conn->flags))
 		return NULL;
 
 	if (opcode == ISCSI_OP_LOGIN || opcode == ISCSI_OP_TEXT) {
@@ -2214,6 +2215,8 @@ void iscsi_conn_unbind(struct iscsi_cls_conn *cls_conn, bool is_active)
 	iscsi_suspend_tx(conn);
 
 	spin_lock_bh(&session->frwd_lock);
+	clear_bit(ISCSI_CONN_FLAG_BOUND, &conn->flags);
+
 	if (!is_active) {
 		/*
 		 * if logout timed out before userspace could even send a PDU
@@ -3317,6 +3320,8 @@ int iscsi_conn_bind(struct iscsi_cls_session *cls_session,
 	spin_lock_bh(&session->frwd_lock);
 	if (is_leading)
 		session->leadconn = conn;
+
+	set_bit(ISCSI_CONN_FLAG_BOUND, &conn->flags);
 	spin_unlock_bh(&session->frwd_lock);
 
 	/*

include/scsi/libiscsi.h

@@ -56,7 +56,7 @@ enum {
 /* Connection flags */
 #define ISCSI_CONN_FLAG_SUSPEND_TX	BIT(0)
 #define ISCSI_CONN_FLAG_SUSPEND_RX	BIT(1)
-
+#define ISCSI_CONN_FLAG_BOUND		BIT(2)
 
 #define ISCSI_ITT_MASK			0x1fff
 #define ISCSI_TOTAL_CMDS_MAX		4096