target: Fix Task Aborted Status (TAS) handling

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>

3 files changed, 18 insertions, 16 deletions

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 70c638f730af..3f0338fff240 100644
--- a/drivers/target/target_core_tmr.c
+++ b/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);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 0a359fa82bd3..51a375453d9b 100644
--- a/drivers/target/target_core_transport.c
+++ b/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)
@@ -2784,13 +2787,17 @@ 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);
@@ -2804,7 +2811,7 @@ 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;
         }
@@ -2819,6 +2826,7 @@ 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;
                 }
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index f13fd09d91dc..ec3e3a3ff4f6 100644
--- a/include/target/target_core_base.h
+++ b/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,