scsi: target/core: Fix TAS handling for aborted commands

The TASK ABORTED STATUS (TAS) bit is defined as follows in SAM:
"TASK_ABORTED: this status shall be returned if a command is aborted by a
command or task management function on another I_T nexus and the control
mode page TAS bit is set to one". TAS handling is spread over the target
core and the iSCSI target driver. If a LUN RESET is received, the target
core will send the TASK_ABORTED response for all commands for which such a
response has to be sent. If an ABORT TASK is received, only the iSCSI
target driver will send the TASK_ABORTED response for the commands for
which that response has to be sent. That is a bug since all target drivers
have to honor the TAS bit. Fix this by moving the code that handles TAS
from the iSCSI target driver into the target core. Additionally, if a
command has been aborted, instead of sending the TASK_ABORTED status from
the context that processes the SCSI command send it from the context of the
ABORT TMF. The core_tmr_abort_task() change in this patch causes the
CMD_T_TAS flag to be set if a TASK_ABORTED status has to be sent back to
the initiator that submitted the command. If that flag has been set
transport_cmd_finish_abort() will send the TASK_ABORTED response.

Cc: Nicholas Bellinger <[e-mail]>
Cc: Mike Christie <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: David Disseldorp <[e-mail]>
Cc: Hannes Reinecke <[e-mail]>
Signed-off-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/target/iscsi/iscsi_target.c

···
 			if (hdr->flags & ISCSI_FLAG_CMD_FINAL)
 				iscsit_stop_dataout_timer(cmd);
 
-			transport_check_aborted_status(se_cmd,
-					(hdr->flags & ISCSI_FLAG_CMD_FINAL));
 			return iscsit_dump_data_payload(conn, payload_length, 1);
 		}
 	} else {
···
 		 * TASK_ABORTED status.
 		 */
 		if (se_cmd->transport_state & CMD_T_ABORTED) {
-			if (hdr->flags & ISCSI_FLAG_CMD_FINAL)
-				if (--cmd->outstanding_r2ts < 1) {
-					iscsit_stop_dataout_timer(cmd);
-					transport_check_aborted_status(
-							se_cmd, 1);
-				}
+			if (hdr->flags & ISCSI_FLAG_CMD_FINAL &&
+			    --cmd->outstanding_r2ts < 1)
+				iscsit_stop_dataout_timer(cmd);
 
 			return iscsit_dump_data_payload(conn, payload_length, 1);
 		}

drivers/target/iscsi/iscsi_target_erl1.c

···
 				return 0;
 			}
 			spin_unlock_bh(&cmd->istate_lock);
-			/*
-			 * Determine if delayed TASK_ABORTED status for WRITEs
-			 * should be sent now if no unsolicited data out
-			 * payloads are expected, or if the delayed status
-			 * should be sent after unsolicited data out with
-			 * ISCSI_FLAG_CMD_FINAL set in iscsi_handle_data_out()
-			 */
-			if (transport_check_aborted_status(se_cmd,
-					(cmd->unsolicited_data == 0)) != 0)
+			if (cmd->se_cmd.transport_state & CMD_T_ABORTED)
 				return 0;
-			/*
-			 * Otherwise send CHECK_CONDITION and sense for
-			 * exception
-			 */
 			return transport_send_check_condition_and_sense(se_cmd,
 					cmd->sense_reason, 0);
 		}
···
 
 			if (!(cmd->cmd_flags &
 					ICF_NON_IMMEDIATE_UNSOLICITED_DATA)) {
-				/*
-				 * Send the delayed TASK_ABORTED status for
-				 * WRITEs if no more unsolicitied data is
-				 * expected.
-				 */
-				if (transport_check_aborted_status(se_cmd, 1)
-						!= 0)
+				if (cmd->se_cmd.transport_state & CMD_T_ABORTED)
 					return 0;
 
 				iscsit_set_dataout_sequence_values(cmd);
···
 
 		if ((cmd->data_direction == DMA_TO_DEVICE) &&
 		    !(cmd->cmd_flags & ICF_NON_IMMEDIATE_UNSOLICITED_DATA)) {
-			/*
-			 * Send the delayed TASK_ABORTED status for WRITEs if
-			 * no more nsolicitied data is expected.
-			 */
-			if (transport_check_aborted_status(se_cmd, 1) != 0)
+			if (cmd->se_cmd.transport_state & CMD_T_ABORTED)
 				return 0;
 
 			iscsit_set_unsoliticed_dataout(cmd);

drivers/target/target_core_tmr.c

···
 		printk("ABORT_TASK: Found referenced %s task_tag: %llu\n",
 			se_cmd->se_tfo->fabric_name, ref_tag);
 
-		if (!__target_check_io_state(se_cmd, se_sess, 0))
+		if (!__target_check_io_state(se_cmd, se_sess,
+					     dev->dev_attrib.emulate_tas))
 			continue;
 
 		spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);

drivers/target/target_core_transport.c

···
 	if (cmd->transport_complete_callback)
 		cmd->transport_complete_callback(cmd, false, NULL);
 
-	if (transport_check_aborted_status(cmd, 1))
+	if (cmd->transport_state & CMD_T_ABORTED)
 		return;
 
 	switch (sense_reason) {
···
 	return true;
 }
 
-static int __transport_check_aborted_status(struct se_cmd *, int);
-
 void target_execute_cmd(struct se_cmd *cmd)
 {
 	/*
···
 	 * If the received CDB has already been aborted stop processing it here.
 	 */
 	spin_lock_irq(&cmd->t_state_lock);
-	if (__transport_check_aborted_status(cmd, 1)) {
+	if (cmd->transport_state & CMD_T_ABORTED) {
 		spin_unlock_irq(&cmd->t_state_lock);
 		return;
 	}
···
 	return cmd->se_tfo->queue_status(cmd);
 }
 EXPORT_SYMBOL(transport_send_check_condition_and_sense);
-
-static int __transport_check_aborted_status(struct se_cmd *cmd, int send_status)
-	__releases(&cmd->t_state_lock)
-	__acquires(&cmd->t_state_lock)
-{
-	int ret;
-
-	assert_spin_locked(&cmd->t_state_lock);
-	WARN_ON_ONCE(!irqs_disabled());
-
-	if (!(cmd->transport_state & CMD_T_ABORTED))
-		return 0;
-	/*
-	 * 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)) {
-		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%08llx\n", cmd->t_task_cdb[0], cmd->tag);
-
-	cmd->se_cmd_flags &= ~SCF_SEND_DELAYED_TAS;
-	cmd->scsi_status = SAM_STAT_TASK_ABORTED;
-	trace_target_cmd_complete(cmd);
-
-	spin_unlock_irq(&cmd->t_state_lock);
-	ret = cmd->se_tfo->queue_status(cmd);
-	if (ret)
-		transport_handle_queue_full(cmd, cmd->se_dev, ret, false);
-	spin_lock_irq(&cmd->t_state_lock);
-
-	return 1;
-}
-
-int transport_check_aborted_status(struct se_cmd *cmd, int send_status)
-{
-	int ret;
-
-	spin_lock_irq(&cmd->t_state_lock);
-	ret = __transport_check_aborted_status(cmd, send_status);
-	spin_unlock_irq(&cmd->t_state_lock);
-
-	return ret;
-}
-EXPORT_SYMBOL(transport_check_aborted_status);
 
 void transport_send_task_abort(struct se_cmd *cmd)
 {

include/target/target_core_base.h

···
 	SCF_SENT_CHECK_CONDITION	= 0x00000800,
 	SCF_OVERFLOW_BIT		= 0x00001000,
 	SCF_UNDERFLOW_BIT		= 0x00002000,
-	SCF_SEND_DELAYED_TAS		= 0x00004000,
 	SCF_ALUA_NON_OPTIMIZED		= 0x00008000,
 	SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC = 0x00020000,
 	SCF_COMPARE_AND_WRITE		= 0x00080000,

include/target/target_core_fabric.h

···
 int	transport_generic_free_cmd(struct se_cmd *, int);
 
 bool	transport_wait_for_tasks(struct se_cmd *);
-int	transport_check_aborted_status(struct se_cmd *, int);
 int	transport_send_check_condition_and_sense(struct se_cmd *,
 		sense_reason_t, int);
 int	target_get_sess_cmd(struct se_cmd *, bool);