target: Fix Task Aborted Status (TAS) handling

commit 68259b5 upstream.

This patch addresses three of long standing issues wrt to Task
Aborted Status (TAS) handling.

The first is the incorrect assumption in core_tmr_handle_tas_abort()
that TASK_ABORTED status is sent for the task referenced by TMR
ABORT_TASK, and sending TASK_ABORTED status for TMR LUN_RESET on
the same nexus the LUN_RESET was received.

The second is to ensure the lun reference count is dropped within
transport_cmd_finish_abort() by calling transport_lun_remove_cmd()
before invoking transport_cmd_check_stop_to_fabric().

The last is to fix the delayed TAS handling to allow outstanding
WRITEs to complete before sending the TASK_ABORTED status. This
includes changing transport_check_aborted_status() to avoid
processing when SCF_SEND_DELAYED_TAS has not be set, and updating
transport_send_task_abort() to drop the SCF_SENT_DELAYED_TAS
check.

Signed-off-by: Alex Leung <amleung21@yahoo.com>
Cc: Alex Leung <amleung21@yahoo.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/target/target_core_tmr.c

@@ -87,14 +87,17 @@ static void core_tmr_handle_tas_abort(
 	struct se_cmd *cmd,
 	int tas)
 {
+	bool remove = true;
 	/*
 	 * TASK ABORTED status (TAS) bit support
 	*/
 	if ((tmr_nacl &&
-	     (tmr_nacl == cmd->se_sess->se_node_acl)) || tas)
+	     (tmr_nacl != cmd->se_sess->se_node_acl)) && tas) {
+		remove = false;
 		transport_send_task_abort(cmd);
+	}
 
-	transport_cmd_finish_abort(cmd, 0);
+	transport_cmd_finish_abort(cmd, remove);
 }
 
 static int target_check_cdb_and_preempt(struct list_head *list,
@@ -150,18 +153,9 @@ void core_tmr_abort_task(
 
 		cancel_work_sync(&se_cmd->work);
 		transport_wait_for_tasks(se_cmd);
-		/*
-		 * Now send SAM_STAT_TASK_ABORTED status for the referenced
-		 * se_cmd descriptor..
-		 */
-		transport_send_task_abort(se_cmd);
-		/*
-		 * Also deal with possible extra acknowledge reference..
-		 */
-		if (se_cmd->se_cmd_flags & SCF_ACK_KREF)
-			target_put_sess_cmd(se_sess, se_cmd);
 
 		target_put_sess_cmd(se_sess, se_cmd);
+		transport_cmd_finish_abort(se_cmd, true);
 
 		printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"
 				" ref_tag: %d\n", ref_tag);

drivers/target/target_core_transport.c

@@ -603,6 +603,9 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd)
 
 void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
 {
+	if (cmd->se_cmd_flags & SCF_SE_LUN_CMD)
+		transport_lun_remove_cmd(cmd);
+
 	if (transport_cmd_check_stop_to_fabric(cmd))
 		return;
 	if (remove)
@@ -2825,13 +2828,17 @@ int transport_check_aborted_status(struct se_cmd *cmd, int send_status)
 	if (!(cmd->transport_state & CMD_T_ABORTED))
 		return 0;
 
-	if (!send_status || (cmd->se_cmd_flags & SCF_SENT_DELAYED_TAS))
+	/*
+	 * If cmd has been aborted but either no status is to be sent or it has
+	 * already been sent, just return
+	 */
+	if (!send_status || !(cmd->se_cmd_flags & SCF_SEND_DELAYED_TAS))
 		return 1;
 
 	pr_debug("Sending delayed SAM_STAT_TASK_ABORTED status for CDB: 0x%02x ITT: 0x%08x\n",
 		 cmd->t_task_cdb[0], cmd->se_tfo->get_task_tag(cmd));
 
-	cmd->se_cmd_flags |= SCF_SENT_DELAYED_TAS;
+	cmd->se_cmd_flags &= ~SCF_SEND_DELAYED_TAS;
 	cmd->scsi_status = SAM_STAT_TASK_ABORTED;
 	trace_target_cmd_complete(cmd);
 	cmd->se_tfo->queue_status(cmd);
@@ -2845,7 +2852,7 @@ void transport_send_task_abort(struct se_cmd *cmd)
 	unsigned long flags;
 
 	spin_lock_irqsave(&cmd->t_state_lock, flags);
-	if (cmd->se_cmd_flags & (SCF_SENT_CHECK_CONDITION | SCF_SENT_DELAYED_TAS)) {
+	if (cmd->se_cmd_flags & (SCF_SENT_CHECK_CONDITION)) {
 		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 		return;
 	}
@@ -2860,6 +2867,7 @@ void transport_send_task_abort(struct se_cmd *cmd)
 	if (cmd->data_direction == DMA_TO_DEVICE) {
 		if (cmd->se_tfo->write_pending_status(cmd) != 0) {
 			cmd->transport_state |= CMD_T_ABORTED;
+			cmd->se_cmd_flags |= SCF_SEND_DELAYED_TAS;
 			smp_mb__after_atomic_inc();
 			return;
 		}

include/target/target_core_base.h

@@ -162,7 +162,7 @@ enum se_cmd_flags_table {
 	SCF_SENT_CHECK_CONDITION	= 0x00000800,
 	SCF_OVERFLOW_BIT		= 0x00001000,
 	SCF_UNDERFLOW_BIT		= 0x00002000,
-	SCF_SENT_DELAYED_TAS		= 0x00004000,
+	SCF_SEND_DELAYED_TAS		= 0x00004000,
 	SCF_ALUA_NON_OPTIMIZED		= 0x00008000,
 	SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC = 0x00020000,
 	SCF_ACK_KREF			= 0x00040000,