Merge git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending

Pull SCSI target fixes from Nicholas Bellinger:
 "Here are the target-pending fixes for v4.12-rc4:

   - ibmviscsis ABORT_TASK handling fixes that missed the v4.12 merge
     window. (Bryant Ly and Michael Cyr)

   - Re-add a target-core check enforcing WRITE overflow reject that was
     relaxed in v4.3, to avoid unsupported iscsi-target immediate data
     overflow. (nab)

   - Fix a target-core-user OOPs during device removal. (MNC + Bryant
     Ly)

   - Fix a long standing iscsi-target potential issue where kthread exit
     did not wait for kthread_should_stop(). (Jiang Yi)

   - Fix a iscsi-target v3.12.y regression OOPs involving initial login
     PDU processing during asynchronous TCP connection close. (MNC +
     nab)

  This is a little larger than usual for an -rc4, primarily due to the
  iscsi-target v3.12.y regression OOPs bug-fix.

  However, it's an important patch as MNC + Hannes where both able to
  trigger it using a reduced iscsi initiator login timeout combined with
  a backend taking a long time to complete I/Os during iscsi login
  driven session reinstatement"

* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  iscsi-target: Always wait for kthread_should_stop() before kthread exit
  iscsi-target: Fix initial login PDU asynchronous socket close OOPs
  tcmu: fix crash during device removal
  target: Re-add check to reject control WRITEs with overflow data
  ibmvscsis: Fix the incorrect req_lim_delta
  ibmvscsis: Clear left-over abort_cmd pointers

8 files changed, 240 insertions, 92 deletions

diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
index d390325c99ec..abf6026645dd 100644
--- a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
+++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
@@ -1170,6 +1170,8 @@ static struct ibmvscsis_cmd *ibmvscsis_get_free_cmd(struct scsi_info *vscsi)
 		cmd = list_first_entry_or_null(&vscsi->free_cmd,
 					       struct ibmvscsis_cmd, list);
 		if (cmd) {
+			if (cmd->abort_cmd)
+				cmd->abort_cmd = NULL;
 			cmd->flags &= ~(DELAY_SEND);
 			list_del(&cmd->list);
 			cmd->iue = iue;
@@ -1774,6 +1776,7 @@ static void ibmvscsis_send_messages(struct scsi_info *vscsi)
 				if (cmd->abort_cmd) {
 					retry = true;
 					cmd->abort_cmd->flags &= ~(DELAY_SEND);
+					cmd->abort_cmd = NULL;
 				}
 
 				/*
@@ -1788,6 +1791,25 @@ static void ibmvscsis_send_messages(struct scsi_info *vscsi)
 					list_del(&cmd->list);
 					ibmvscsis_free_cmd_resources(vscsi,
 								     cmd);
+					/*
+					 * With a successfully aborted op
+					 * through LIO we want to increment the
+					 * the vscsi credit so that when we dont
+					 * send a rsp to the original scsi abort
+					 * op (h_send_crq), but the tm rsp to
+					 * the abort is sent, the credit is
+					 * correctly sent with the abort tm rsp.
+					 * We would need 1 for the abort tm rsp
+					 * and 1 credit for the aborted scsi op.
+					 * Thus we need to increment here.
+					 * Also we want to increment the credit
+					 * here because we want to make sure
+					 * cmd is actually released first
+					 * otherwise the client will think it
+					 * it can send a new cmd, and we could
+					 * find ourselves short of cmd elements.
+					 */
+					vscsi->credit += 1;
 				} else {
 					iue = cmd->iue;
 
@@ -2962,10 +2984,7 @@ static long srp_build_response(struct scsi_info *vscsi,
 
 	rsp->opcode = SRP_RSP;
 
-	if (vscsi->credit > 0 && vscsi->state == SRP_PROCESSING)
-		rsp->req_lim_delta = cpu_to_be32(vscsi->credit);
-	else
-		rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
+	rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
 	rsp->tag = cmd->rsp.tag;
 	rsp->flags = 0;
 
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 26a9bcd5ee6a..0d8f81591bed 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -3790,6 +3790,8 @@ int iscsi_target_tx_thread(void *arg)
 {
 	int ret = 0;
 	struct iscsi_conn *conn = arg;
+	bool conn_freed = false;
+
 	/*
 	 * Allow ourselves to be interrupted by SIGINT so that a
 	 * connection recovery / failure event can be triggered externally.
@@ -3815,12 +3817,14 @@ get_immediate:
 			goto transport_err;
 
 		ret = iscsit_handle_response_queue(conn);
-		if (ret == 1)
+		if (ret == 1) {
 			goto get_immediate;
-		else if (ret == -ECONNRESET)
+		} else if (ret == -ECONNRESET) {
+			conn_freed = true;
 			goto out;
-		else if (ret < 0)
+		} else if (ret < 0) {
 			goto transport_err;
+		}
 	}
 
 transport_err:
@@ -3830,8 +3834,13 @@ transport_err:
 	 * responsible for cleaning up the early connection failure.
 	 */
 	if (conn->conn_state != TARG_CONN_STATE_IN_LOGIN)
-		iscsit_take_action_for_connection_exit(conn);
+		iscsit_take_action_for_connection_exit(conn, &conn_freed);
 out:
+	if (!conn_freed) {
+		while (!kthread_should_stop()) {
+			msleep(100);
+		}
+	}
 	return 0;
 }
 
@@ -4004,6 +4013,7 @@ int iscsi_target_rx_thread(void *arg)
 {
 	int rc;
 	struct iscsi_conn *conn = arg;
+	bool conn_freed = false;
 
 	/*
 	 * Allow ourselves to be interrupted by SIGINT so that a
@@ -4016,7 +4026,7 @@ int iscsi_target_rx_thread(void *arg)
 	 */
 	rc = wait_for_completion_interruptible(&conn->rx_login_comp);
 	if (rc < 0 || iscsi_target_check_conn_state(conn))
-		return 0;
+		goto out;
 
 	if (!conn->conn_transport->iscsit_get_rx_pdu)
 		return 0;
@@ -4025,7 +4035,15 @@ int iscsi_target_rx_thread(void *arg)
 
 	if (!signal_pending(current))
 		atomic_set(&conn->transport_failed, 1);
-	iscsit_take_action_for_connection_exit(conn);
+	iscsit_take_action_for_connection_exit(conn, &conn_freed);
+
+out:
+	if (!conn_freed) {
+		while (!kthread_should_stop()) {
+			msleep(100);
+		}
+	}
+
 	return 0;
 }
 
diff --git a/drivers/target/iscsi/iscsi_target_erl0.c b/drivers/target/iscsi/iscsi_target_erl0.c
index 9a96e17bf7cd..7fe2aa73cff6 100644
--- a/drivers/target/iscsi/iscsi_target_erl0.c
+++ b/drivers/target/iscsi/iscsi_target_erl0.c
@@ -930,8 +930,10 @@ static void iscsit_handle_connection_cleanup(struct iscsi_conn *conn)
 	}
 }
 
-void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn)
+void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn, bool *conn_freed)
 {
+	*conn_freed = false;
+
 	spin_lock_bh(&conn->state_lock);
 	if (atomic_read(&conn->connection_exit)) {
 		spin_unlock_bh(&conn->state_lock);
@@ -942,6 +944,7 @@ void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn)
 	if (conn->conn_state == TARG_CONN_STATE_IN_LOGOUT) {
 		spin_unlock_bh(&conn->state_lock);
 		iscsit_close_connection(conn);
+		*conn_freed = true;
 		return;
 	}
 
@@ -955,4 +958,5 @@ void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn)
 	spin_unlock_bh(&conn->state_lock);
 
 	iscsit_handle_connection_cleanup(conn);
+	*conn_freed = true;
 }
diff --git a/drivers/target/iscsi/iscsi_target_erl0.h b/drivers/target/iscsi/iscsi_target_erl0.h
index 60e69e2af6ed..3822d9cd1230 100644
--- a/drivers/target/iscsi/iscsi_target_erl0.h
+++ b/drivers/target/iscsi/iscsi_target_erl0.h
@@ -15,6 +15,6 @@ extern int iscsit_stop_time2retain_timer(struct iscsi_session *);
 extern void iscsit_connection_reinstatement_rcfr(struct iscsi_conn *);
 extern void iscsit_cause_connection_reinstatement(struct iscsi_conn *, int);
 extern void iscsit_fall_back_to_erl0(struct iscsi_session *);
-extern void iscsit_take_action_for_connection_exit(struct iscsi_conn *);
+extern void iscsit_take_action_for_connection_exit(struct iscsi_conn *, bool *);
 
 #endif   /*** ISCSI_TARGET_ERL0_H ***/
diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 66238477137b..92b96b51d506 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1464,5 +1464,9 @@ int iscsi_target_login_thread(void *arg)
 			break;
 	}
 
+	while (!kthread_should_stop()) {
+		msleep(100);
+	}
+
 	return 0;
 }
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 7ccc9c1cbfd1..6f88b31242b0 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -493,14 +493,60 @@ static void iscsi_target_restore_sock_callbacks(struct iscsi_conn *conn)
 
 static int iscsi_target_do_login(struct iscsi_conn *, struct iscsi_login *);
 
-static bool iscsi_target_sk_state_check(struct sock *sk)
+static bool __iscsi_target_sk_check_close(struct sock *sk)
 {
 	if (sk->sk_state == TCP_CLOSE_WAIT || sk->sk_state == TCP_CLOSE) {
-		pr_debug("iscsi_target_sk_state_check: TCP_CLOSE_WAIT|TCP_CLOSE,"
+		pr_debug("__iscsi_target_sk_check_close: TCP_CLOSE_WAIT|TCP_CLOSE,"
 			"returning FALSE\n");
-		return false;
+		return true;
 	}
-	return true;
+	return false;
+}
+
+static bool iscsi_target_sk_check_close(struct iscsi_conn *conn)
+{
+	bool state = false;
+
+	if (conn->sock) {
+		struct sock *sk = conn->sock->sk;
+
+		read_lock_bh(&sk->sk_callback_lock);
+		state = (__iscsi_target_sk_check_close(sk) ||
+			 test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags));
+		read_unlock_bh(&sk->sk_callback_lock);
+	}
+	return state;
+}
+
+static bool iscsi_target_sk_check_flag(struct iscsi_conn *conn, unsigned int flag)
+{
+	bool state = false;
+
+	if (conn->sock) {
+		struct sock *sk = conn->sock->sk;
+
+		read_lock_bh(&sk->sk_callback_lock);
+		state = test_bit(flag, &conn->login_flags);
+		read_unlock_bh(&sk->sk_callback_lock);
+	}
+	return state;
+}
+
+static bool iscsi_target_sk_check_and_clear(struct iscsi_conn *conn, unsigned int flag)
+{
+	bool state = false;
+
+	if (conn->sock) {
+		struct sock *sk = conn->sock->sk;
+
+		write_lock_bh(&sk->sk_callback_lock);
+		state = (__iscsi_target_sk_check_close(sk) ||
+			 test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags));
+		if (!state)
+			clear_bit(flag, &conn->login_flags);
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+	return state;
 }
 
 static void iscsi_target_login_drop(struct iscsi_conn *conn, struct iscsi_login *login)
@@ -540,6 +586,20 @@ static void iscsi_target_do_login_rx(struct work_struct *work)
 
 	pr_debug("entering iscsi_target_do_login_rx, conn: %p, %s:%d\n",
 			conn, current->comm, current->pid);
+	/*
+	 * If iscsi_target_do_login_rx() has been invoked by ->sk_data_ready()
+	 * before initial PDU processing in iscsi_target_start_negotiation()
+	 * has completed, go ahead and retry until it's cleared.
+	 *
+	 * Otherwise if the TCP connection drops while this is occuring,
+	 * iscsi_target_start_negotiation() will detect the failure, call
+	 * cancel_delayed_work_sync(&conn->login_work), and cleanup the
+	 * remaining iscsi connection resources from iscsi_np process context.
+	 */
+	if (iscsi_target_sk_check_flag(conn, LOGIN_FLAGS_INITIAL_PDU)) {
+		schedule_delayed_work(&conn->login_work, msecs_to_jiffies(10));
+		return;
+	}
 
 	spin_lock(&tpg->tpg_state_lock);
 	state = (tpg->tpg_state == TPG_STATE_ACTIVE);
@@ -547,26 +607,12 @@ static void iscsi_target_do_login_rx(struct work_struct *work)
 
 	if (!state) {
 		pr_debug("iscsi_target_do_login_rx: tpg_state != TPG_STATE_ACTIVE\n");
-		iscsi_target_restore_sock_callbacks(conn);
-		iscsi_target_login_drop(conn, login);
-		iscsit_deaccess_np(np, tpg, tpg_np);
-		return;
+		goto err;
 	}
 
-	if (conn->sock) {
-		struct sock *sk = conn->sock->sk;
-
-		read_lock_bh(&sk->sk_callback_lock);
-		state = iscsi_target_sk_state_check(sk);
-		read_unlock_bh(&sk->sk_callback_lock);
-
-		if (!state) {
-			pr_debug("iscsi_target_do_login_rx, TCP state CLOSE\n");
-			iscsi_target_restore_sock_callbacks(conn);
-			iscsi_target_login_drop(conn, login);
-			iscsit_deaccess_np(np, tpg, tpg_np);
-			return;
-		}
+	if (iscsi_target_sk_check_close(conn)) {
+		pr_debug("iscsi_target_do_login_rx, TCP state CLOSE\n");
+		goto err;
 	}
 
 	conn->login_kworker = current;
@@ -584,34 +630,29 @@ static void iscsi_target_do_login_rx(struct work_struct *work)
 	flush_signals(current);
 	conn->login_kworker = NULL;
 
-	if (rc < 0) {
-		iscsi_target_restore_sock_callbacks(conn);
-		iscsi_target_login_drop(conn, login);
-		iscsit_deaccess_np(np, tpg, tpg_np);
-		return;
-	}
+	if (rc < 0)
+		goto err;
 
 	pr_debug("iscsi_target_do_login_rx after rx_login_io, %p, %s:%d\n",
 			conn, current->comm, current->pid);
 
 	rc = iscsi_target_do_login(conn, login);
 	if (rc < 0) {
-		iscsi_target_restore_sock_callbacks(conn);
-		iscsi_target_login_drop(conn, login);
-		iscsit_deaccess_np(np, tpg, tpg_np);
+		goto err;
 	} else if (!rc) {
-		if (conn->sock) {
-			struct sock *sk = conn->sock->sk;
-
-			write_lock_bh(&sk->sk_callback_lock);
-			clear_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags);
-			write_unlock_bh(&sk->sk_callback_lock);
-		}
+		if (iscsi_target_sk_check_and_clear(conn, LOGIN_FLAGS_READ_ACTIVE))
+			goto err;
 	} else if (rc == 1) {
 		iscsi_target_nego_release(conn);
 		iscsi_post_login_handler(np, conn, zero_tsih);
 		iscsit_deaccess_np(np, tpg, tpg_np);
 	}
+	return;
+
+err:
+	iscsi_target_restore_sock_callbacks(conn);
+	iscsi_target_login_drop(conn, login);
+	iscsit_deaccess_np(np, tpg, tpg_np);
 }
 
 static void iscsi_target_do_cleanup(struct work_struct *work)
@@ -659,31 +700,54 @@ static void iscsi_target_sk_state_change(struct sock *sk)
 		orig_state_change(sk);
 		return;
 	}
+	state = __iscsi_target_sk_check_close(sk);
+	pr_debug("__iscsi_target_sk_close_change: state: %d\n", state);
+
 	if (test_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags)) {
 		pr_debug("Got LOGIN_FLAGS_READ_ACTIVE=1 sk_state_change"
 			 " conn: %p\n", conn);
+		if (state)
+			set_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags);
 		write_unlock_bh(&sk->sk_callback_lock);
 		orig_state_change(sk);
 		return;
 	}
-	if (test_and_set_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags)) {
+	if (test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags)) {
 		pr_debug("Got LOGIN_FLAGS_CLOSED=1 sk_state_change conn: %p\n",
 			 conn);
 		write_unlock_bh(&sk->sk_callback_lock);
 		orig_state_change(sk);
 		return;
 	}
+	/*
+	 * If the TCP connection has dropped, go ahead and set LOGIN_FLAGS_CLOSED,
+	 * but only queue conn->login_work -> iscsi_target_do_login_rx()
+	 * processing if LOGIN_FLAGS_INITIAL_PDU has already been cleared.
+	 *
+	 * When iscsi_target_do_login_rx() runs, iscsi_target_sk_check_close()
+	 * will detect the dropped TCP connection from delayed workqueue context.
+	 *
+	 * If LOGIN_FLAGS_INITIAL_PDU is still set, which means the initial
+	 * iscsi_target_start_negotiation() is running, iscsi_target_do_login()
+	 * via iscsi_target_sk_check_close() or iscsi_target_start_negotiation()
+	 * via iscsi_target_sk_check_and_clear() is responsible for detecting the
+	 * dropped TCP connection in iscsi_np process context, and cleaning up
+	 * the remaining iscsi connection resources.
+	 */
+	if (state) {
+		pr_debug("iscsi_target_sk_state_change got failed state\n");
+		set_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags);
+		state = test_bit(LOGIN_FLAGS_INITIAL_PDU, &conn->login_flags);
+		write_unlock_bh(&sk->sk_callback_lock);
 
-	state = iscsi_target_sk_state_check(sk);
-	write_unlock_bh(&sk->sk_callback_lock);
-
-	pr_debug("iscsi_target_sk_state_change: state: %d\n", state);
+		orig_state_change(sk);
 
-	if (!state) {
-		pr_debug("iscsi_target_sk_state_change got failed state\n");
-		schedule_delayed_work(&conn->login_cleanup_work, 0);
+		if (!state)
+			schedule_delayed_work(&conn->login_work, 0);
 		return;
 	}
+	write_unlock_bh(&sk->sk_callback_lock);
+
 	orig_state_change(sk);
 }
 
@@ -946,6 +1010,15 @@ static int iscsi_target_do_login(struct iscsi_conn *conn, struct iscsi_login *lo
 			if (iscsi_target_handle_csg_one(conn, login) < 0)
 				return -1;
 			if (login_rsp->flags & ISCSI_FLAG_LOGIN_TRANSIT) {
+				/*
+				 * Check to make sure the TCP connection has not
+				 * dropped asynchronously while session reinstatement
+				 * was occuring in this kthread context, before
+				 * transitioning to full feature phase operation.
+				 */
+				if (iscsi_target_sk_check_close(conn))
+					return -1;
+
 				login->tsih = conn->sess->tsih;
 				login->login_complete = 1;
 				iscsi_target_restore_sock_callbacks(conn);
@@ -972,21 +1045,6 @@ static int iscsi_target_do_login(struct iscsi_conn *conn, struct iscsi_login *lo
 		break;
 	}
 
-	if (conn->sock) {
-		struct sock *sk = conn->sock->sk;
-		bool state;
-
-		read_lock_bh(&sk->sk_callback_lock);
-		state = iscsi_target_sk_state_check(sk);
-		read_unlock_bh(&sk->sk_callback_lock);
-
-		if (!state) {
-			pr_debug("iscsi_target_do_login() failed state for"
-				 " conn: %p\n", conn);
-			return -1;
-		}
-	}
-
 	return 0;
 }
 
@@ -1255,10 +1313,22 @@ int iscsi_target_start_negotiation(
 
 		write_lock_bh(&sk->sk_callback_lock);
 		set_bit(LOGIN_FLAGS_READY, &conn->login_flags);
+		set_bit(LOGIN_FLAGS_INITIAL_PDU, &conn->login_flags);
 		write_unlock_bh(&sk->sk_callback_lock);
 	}
-
+	/*
+	 * If iscsi_target_do_login returns zero to signal more PDU
+	 * exchanges are required to complete the login, go ahead and
+	 * clear LOGIN_FLAGS_INITIAL_PDU but only if the TCP connection
+	 * is still active.
+	 *
+	 * Otherwise if TCP connection dropped asynchronously, go ahead
+	 * and perform connection cleanup now.
+	 */
 	ret = iscsi_target_do_login(conn, login);
+	if (!ret && iscsi_target_sk_check_and_clear(conn, LOGIN_FLAGS_INITIAL_PDU))
+		ret = -1;
+
 	if (ret < 0) {
 		cancel_delayed_work_sync(&conn->login_work);
 		cancel_delayed_work_sync(&conn->login_cleanup_work);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 37f57357d4a0..6025935036c9 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1160,15 +1160,28 @@ target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
 	if (cmd->unknown_data_length) {
 		cmd->data_length = size;
 	} else if (size != cmd->data_length) {
-		pr_warn("TARGET_CORE[%s]: Expected Transfer Length:"
+		pr_warn_ratelimited("TARGET_CORE[%s]: Expected Transfer Length:"
 			" %u does not match SCSI CDB Length: %u for SAM Opcode:"
 			" 0x%02x\n", cmd->se_tfo->get_fabric_name(),
 				cmd->data_length, size, cmd->t_task_cdb[0]);
 
-		if (cmd->data_direction == DMA_TO_DEVICE &&
-		    cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
-			pr_err("Rejecting underflow/overflow WRITE data\n");
-			return TCM_INVALID_CDB_FIELD;
+		if (cmd->data_direction == DMA_TO_DEVICE) {
+			if (cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
+				pr_err_ratelimited("Rejecting underflow/overflow"
+						   " for WRITE data CDB\n");
+				return TCM_INVALID_CDB_FIELD;
+			}
+			/*
+			 * Some fabric drivers like iscsi-target still expect to
+			 * always reject overflow writes.  Reject this case until
+			 * full fabric driver level support for overflow writes
+			 * is introduced tree-wide.
+			 */
+			if (size > cmd->data_length) {
+				pr_err_ratelimited("Rejecting overflow for"
+						   " WRITE control CDB\n");
+				return TCM_INVALID_CDB_FIELD;
+			}
 		}
 		/*
 		 * Reject READ_* or WRITE_* with overflow/underflow for
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 9045837f748b..beb5f098f32d 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -97,7 +97,7 @@ struct tcmu_hba {
 
 struct tcmu_dev {
 	struct list_head node;
-
+	struct kref kref;
 	struct se_device se_dev;
 
 	char *name;
@@ -969,6 +969,7 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
 	udev = kzalloc(sizeof(struct tcmu_dev), GFP_KERNEL);
 	if (!udev)
 		return NULL;
+	kref_init(&udev->kref);
 
 	udev->name = kstrdup(name, GFP_KERNEL);
 	if (!udev->name) {
@@ -1145,6 +1146,24 @@ static int tcmu_open(struct uio_info *info, struct inode *inode)
 	return 0;
 }
 
+static void tcmu_dev_call_rcu(struct rcu_head *p)
+{
+	struct se_device *dev = container_of(p, struct se_device, rcu_head);
+	struct tcmu_dev *udev = TCMU_DEV(dev);
+
+	kfree(udev->uio_info.name);
+	kfree(udev->name);
+	kfree(udev);
+}
+
+static void tcmu_dev_kref_release(struct kref *kref)
+{
+	struct tcmu_dev *udev = container_of(kref, struct tcmu_dev, kref);
+	struct se_device *dev = &udev->se_dev;
+
+	call_rcu(&dev->rcu_head, tcmu_dev_call_rcu);
+}
+
 static int tcmu_release(struct uio_info *info, struct inode *inode)
 {
 	struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
@@ -1152,7 +1171,8 @@ static int tcmu_release(struct uio_info *info, struct inode *inode)
 	clear_bit(TCMU_DEV_BIT_OPEN, &udev->flags);
 
 	pr_debug("close\n");
-
+	/* release ref from configure */
+	kref_put(&udev->kref, tcmu_dev_kref_release);
 	return 0;
 }
 
@@ -1272,6 +1292,12 @@ static int tcmu_configure_device(struct se_device *dev)
 		dev->dev_attrib.hw_max_sectors = 128;
 	dev->dev_attrib.hw_queue_depth = 128;
 
+	/*
+	 * Get a ref incase userspace does a close on the uio device before
+	 * LIO has initiated tcmu_free_device.
+	 */
+	kref_get(&udev->kref);
+
 	ret = tcmu_netlink_event(TCMU_CMD_ADDED_DEVICE, udev->uio_info.name,
 				 udev->uio_info.uio_dev->minor);
 	if (ret)
@@ -1284,11 +1310,13 @@ static int tcmu_configure_device(struct se_device *dev)
 	return 0;
 
 err_netlink:
+	kref_put(&udev->kref, tcmu_dev_kref_release);
 	uio_unregister_device(&udev->uio_info);
 err_register:
 	vfree(udev->mb_addr);
 err_vzalloc:
 	kfree(info->name);
+	info->name = NULL;
 
 	return ret;
 }
@@ -1302,14 +1330,6 @@ static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd)
 	return -EINVAL;
 }
 
-static void tcmu_dev_call_rcu(struct rcu_head *p)
-{
-	struct se_device *dev = container_of(p, struct se_device, rcu_head);
-	struct tcmu_dev *udev = TCMU_DEV(dev);
-
-	kfree(udev);
-}
-
 static bool tcmu_dev_configured(struct tcmu_dev *udev)
 {
 	return udev->uio_info.uio_dev ? true : false;
@@ -1364,10 +1384,10 @@ static void tcmu_free_device(struct se_device *dev)
 				   udev->uio_info.uio_dev->minor);
 
 		uio_unregister_device(&udev->uio_info);
-		kfree(udev->uio_info.name);
-		kfree(udev->name);
 	}
-	call_rcu(&dev->rcu_head, tcmu_dev_call_rcu);
+
+	/* release ref from init */
+	kref_put(&udev->kref, tcmu_dev_kref_release);
 }
 
 enum {