Instead of invoking target driver callback functions from the
context that handles an abort or LUN RESET task management function,
only set the abort flag from that context and perform the actual
abort handling from the context of the regular command processing
flow. This approach has the following advantages:
- The task management function code becomes much easier to read and
to verify since the number of potential race conditions against
the command processing flow is strongly reduced.
- It is no longer needed to store the command state into the command
itself since that information is no longer needed from the context
where a task management function is processed.
Notes:
- With this patch applied the CMD_T_ABORTED flag is checked at two points
by the target core: just before local execution of a command starts
(see also target_execute_cmd()) and also just before the response is
sent (see also target_complete_cmd()).
- A new reference count is introduced that tracks the number of
references held by the target driver, namely se_cmd.tgt_ref.
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Andy Grover <agrover@xxxxxxxxxx>
Cc: David Disseldorp <ddiss@xxxxxxx>
---
drivers/target/target_core_internal.h | 3 +-
drivers/target/target_core_tmr.c | 65 +++++-------
drivers/target/target_core_transport.c | 183 ++++++++++++++++-----------------
include/target/target_core_base.h | 1 +
4 files changed, 117 insertions(+), 135 deletions(-)
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index 48de996ad28d..944085bff6af 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -136,7 +136,6 @@ int init_se_kmem_caches(void);
void release_se_kmem_caches(void);
u32 scsi_get_new_index(scsi_index_t);
void transport_subsystem_check_init(void);
-void transport_cmd_finish_abort(struct se_cmd *, int);
unsigned char *transport_dump_cmd_direction(struct se_cmd *);
void transport_dump_dev_state(struct se_device *, char *, int *);
void transport_dump_dev_info(struct se_device *, struct se_lun *,
@@ -147,7 +146,7 @@ int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int);
void transport_clear_lun_ref(struct se_lun *);
int __target_put_sess_cmd(struct se_cmd *se_cmd);
-void transport_send_task_abort(struct se_cmd *);
+void target_show_cmd(const char *ctxt, struct se_cmd *cmd);
sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size);
void target_qf_do_work(struct work_struct *work);
bool target_check_wce(struct se_device *dev);
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 161c8b8482db..980d94277c8d 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -75,25 +75,6 @@ void core_tmr_release_req(struct se_tmr_req *tmr)
kfree(tmr);
}
-static void core_tmr_handle_tas_abort(struct se_cmd *cmd, int tas)
-{
- unsigned long flags;
- bool remove = true, send_tas;
- /*
- * TASK ABORTED status (TAS) bit support
- */
- spin_lock_irqsave(&cmd->t_state_lock, flags);
- send_tas = (cmd->transport_state & CMD_T_TAS);
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-
- if (send_tas) {
- remove = false;
- transport_send_task_abort(cmd);
- }
-
- transport_cmd_finish_abort(cmd, remove);
-}
-
static int target_check_cdb_and_preempt(struct list_head *list,
struct se_cmd *cmd)
{
@@ -192,13 +173,13 @@ void core_tmr_abort_task(
continue;
}
+ se_cmd->send_abort_response = false;
list_del_init(&se_cmd->se_cmd_list);
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
- cancel_work_sync(&se_cmd->work);
- transport_wait_for_tasks(se_cmd);
+ while (!wait_for_completion_timeout(&se_cmd->complete, 180 * HZ))
+ target_show_cmd(__func__, se_cmd);
- transport_cmd_finish_abort(se_cmd, true);
__target_put_sess_cmd(se_cmd);
printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"
@@ -295,14 +276,30 @@ static void core_tmr_drain_tmr_list(
(preempt_and_abort_list) ? "Preempt" : "", tmr_p,
tmr_p->function, tmr_p->response, cmd->t_state);
- cancel_work_sync(&cmd->work);
- transport_wait_for_tasks(cmd);
-
- transport_cmd_finish_abort(cmd, 1);
+ while (!wait_for_completion_timeout(&cmd->complete, 180 * HZ))
+ target_show_cmd(__func__, cmd);
__target_put_sess_cmd(cmd);
}
}
+/**
+ * core_tmr_drain_state_list() - abort SCSI commands associated with a device
+ *
+ * @dev: Device for which to abort outstanding SCSI commands.
+ * @prout_cmd: Pointer to the SCSI PREEMPT AND ABORT if this function is called
+ * to realize the PREEMPT AND ABORT functionality.
+ * @tmr_sess: Session through which the LUN RESET has been received.
+ * @tas: Task Aborted Status (TAS) bit from the SCSI control mode page.
+ * A quote from SPC-4, paragraph "7.5.10 Control mode page":
+ * "A task aborted status (TAS) bit set to zero specifies that
+ * aborted commands shall be terminated by the device server
+ * without any response to the application client. A TAS bit set
+ * to one specifies that commands aborted by the actions of an I_T
+ * nexus other than the I_T nexus on which the command was
+ * received shall be completed with TASK ABORTED status."
+ * @preempt_and_abort_list: For the PREEMPT AND ABORT functionality, a list
+ * with registrations that will be preempted.
+ */
static void core_tmr_drain_state_list(
struct se_device *dev,
struct se_cmd *prout_cmd,
@@ -311,6 +308,7 @@ static void core_tmr_drain_state_list(
struct list_head *preempt_and_abort_list)
{
LIST_HEAD(drain_task_list);
+ struct se_node_acl *tmr_nacl = tmr_sess ? tmr_sess->se_node_acl : NULL;
struct se_session *sess;
struct se_cmd *cmd, *next;
unsigned long flags;
@@ -365,6 +363,8 @@ static void core_tmr_drain_state_list(
list_move_tail(&cmd->state_list, &drain_task_list);
cmd->state_active = false;
+ if (tmr_nacl && tmr_nacl != cmd->se_sess->se_node_acl && tas)
+ cmd->send_abort_response = true;
}
spin_unlock_irqrestore(&dev->execute_task_lock, flags);
@@ -387,17 +387,8 @@ static void core_tmr_drain_state_list(
(cmd->transport_state & CMD_T_STOP) != 0,
(cmd->transport_state & CMD_T_SENT) != 0);
- /*
- * If the command may be queued onto a workqueue cancel it now.
- *
- * This is equivalent to removal from the execute queue in the
- * loop above, but we do it down here given that
- * cancel_work_sync may block.
- */
- cancel_work_sync(&cmd->work);
- transport_wait_for_tasks(cmd);
-
- core_tmr_handle_tas_abort(cmd, tas);
+ while (!wait_for_completion_timeout(&cmd->complete, 180 * HZ))
+ target_show_cmd(__func__, cmd);
__target_put_sess_cmd(cmd);
}
}
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 533b584c2806..aac1fc1b2a7c 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -644,25 +644,6 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd)
percpu_ref_put(&lun->lun_ref);
}
-void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
-{
- bool ack_kref = (cmd->se_cmd_flags & SCF_ACK_KREF);
-
- if (cmd->se_cmd_flags & SCF_SE_LUN_CMD)
- transport_lun_remove_cmd(cmd);
- /*
- * Allow the fabric driver to unmap any resources before
- * releasing the descriptor via TFO->release_cmd()
- */
- if (remove)
- cmd->se_tfo->aborted_task(cmd);
-
- if (transport_cmd_check_stop_to_fabric(cmd))
- return;
- if (remove && ack_kref)
- transport_put_cmd(cmd);
-}
-
static void target_complete_failure_work(struct work_struct *work)
{
struct se_cmd *cmd = container_of(work, struct se_cmd, work);
@@ -694,14 +675,58 @@ static unsigned char *transport_get_sense_buffer(struct se_cmd *cmd)
return cmd->sense_buffer;
}
+static void transport_handle_abort(struct se_cmd *cmd)
+{
+ bool ack_kref = cmd->se_cmd_flags & SCF_ACK_KREF;
+
+ transport_lun_remove_cmd(cmd);
+
+ if (cmd->send_abort_response) {
+ cmd->scsi_status = SAM_STAT_TASK_ABORTED;
+ pr_debug("Setting SAM_STAT_TASK_ABORTED status for CDB: 0x%02x, ITT: 0x%08llx\n",
+ cmd->t_task_cdb[0], cmd->tag);
+ trace_target_cmd_complete(cmd);
+ cmd->se_tfo->queue_status(cmd);
+ transport_cmd_check_stop_to_fabric(cmd);
+ } else {
+ /*
+ * Allow the fabric driver to unmap any resources before
+ * releasing the descriptor via TFO->release_cmd()
+ */
+ cmd->se_tfo->aborted_task(cmd);
+ /*
+ * To do: establish a unit attention condition on the I_T
+ * nexus associated with cmd. See also the paragraph "Aborting
+ * commands" in SAM.
+ */
+ if (transport_cmd_check_stop_to_fabric(cmd) == 0 && ack_kref)
+ transport_put_cmd(cmd);
+ }
+}
+
+static void target_abort_work(struct work_struct *work)
+{
+ struct se_cmd *cmd = container_of(work, struct se_cmd, work);
+
+ transport_handle_abort(cmd);
+}
+
+/* May be called from interrupt context so must not sleep. */
void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
{
struct se_device *dev = cmd->se_dev;
int success = scsi_status == GOOD;
unsigned long flags;
- cmd->scsi_status = scsi_status;
+ if (cmd->transport_state & CMD_T_ABORTED) {
+ INIT_WORK(&cmd->work, target_abort_work);
+ goto queue_work;
+ } else if (cmd->transport_state & CMD_T_STOP) {
+ complete_all(&cmd->t_transport_stop_comp);
+ return;
+ }
+ cmd->scsi_status = scsi_status;
spin_lock_irqsave(&cmd->t_state_lock, flags);
cmd->transport_state &= ~CMD_T_BUSY;
@@ -714,16 +739,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
success = 1;
}
- /*
- * Check for case where an explicit ABORT_TASK has been received
- * and transport_wait_for_tasks() will be waiting for completion..
- */
- if (cmd->transport_state & CMD_T_ABORTED ||
- cmd->transport_state & CMD_T_STOP) {
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- complete_all(&cmd->t_transport_stop_comp);
- return;
- } else if (!success) {
+ if (!success) {
INIT_WORK(&cmd->work, target_complete_failure_work);
} else {
INIT_WORK(&cmd->work, target_complete_ok_work);
@@ -733,6 +749,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
cmd->transport_state |= (CMD_T_COMPLETE | CMD_T_ACTIVE);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+queue_work:
if (cmd->se_cmd_flags & SCF_USE_CPUID)
queue_work_on(cmd->cpuid, target_completion_wq, &cmd->work);
else
@@ -1215,6 +1232,7 @@ void transport_init_se_cmd(
INIT_LIST_HEAD(&cmd->state_list);
init_completion(&cmd->t_transport_stop_comp);
init_completion(&cmd->cmd_wait_comp);
+ init_completion(&cmd->complete);
spin_lock_init(&cmd->t_state_lock);
kref_init(&cmd->cmd_kref);
atomic_set(&cmd->tgt_ref, 1);
@@ -1886,6 +1904,7 @@ void target_execute_cmd(struct se_cmd *cmd)
spin_lock_irq(&cmd->t_state_lock);
if (__transport_check_aborted_status(cmd, 1)) {
spin_unlock_irq(&cmd->t_state_lock);
+ transport_handle_abort(cmd);
return;
}
if (cmd->transport_state & CMD_T_STOP) {
@@ -2494,15 +2513,11 @@ static void target_wait_free_cmd(struct se_cmd *cmd, bool *aborted, bool *tas)
int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
{
- int ret = 0;
bool aborted = false, tas = false;
if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) {
if (wait_for_tasks && (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
target_wait_free_cmd(cmd, &aborted, &tas);
-
- if (!aborted || tas)
- ret = transport_put_cmd(cmd);
} else {
if (wait_for_tasks)
target_wait_free_cmd(cmd, &aborted, &tas);
@@ -2516,23 +2531,12 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
if (cmd->se_lun)
transport_lun_remove_cmd(cmd);
-
- if (!aborted || tas)
- ret = transport_put_cmd(cmd);
}
- /*
- * If the task has been internally aborted due to TMR ABORT_TASK
- * or LUN_RESET, target_core_tmr.c is responsible for performing
- * the remaining calls to target_put_sess_cmd(), and not the
- * callers of this function.
- */
if (aborted) {
pr_debug("Detected CMD_T_ABORTED for ITT: %llu\n", cmd->tag);
wait_for_completion(&cmd->cmd_wait_comp);
- transport_put_cmd(cmd);
- ret = 1;
}
- return ret;
+ return transport_put_cmd(cmd);
}
EXPORT_SYMBOL(transport_generic_free_cmd);
@@ -2644,6 +2648,43 @@ int target_put_sess_cmd(struct se_cmd *se_cmd)
}
EXPORT_SYMBOL(target_put_sess_cmd);
+static const char *data_dir_name(enum dma_data_direction d)
+{
+ switch (d) {
+ case DMA_BIDIRECTIONAL: return "BIDI";
+ case DMA_TO_DEVICE: return "WRITE";
+ case DMA_FROM_DEVICE: return "READ";
+ case DMA_NONE: return "NONE";
+ default: return "(?)";
+ }
+}
+
+static const char *cmd_state_name(enum transport_state_table t)
+{
+ switch (t) {
+ case TRANSPORT_NO_STATE: return "NO_STATE";
+ case TRANSPORT_NEW_CMD: return "NEW_CMD";
+ case TRANSPORT_WRITE_PENDING: return "WRITE_PENDING";
+ case TRANSPORT_PROCESSING: return "PROCESSING";
+ case TRANSPORT_COMPLETE: return "COMPLETE";
+ case TRANSPORT_ISTATE_PROCESSING:
+ return "ISTATE_PROCESSING";
+ case TRANSPORT_COMPLETE_QF_WP: return "COMPLETE_QF_WP";
+ case TRANSPORT_COMPLETE_QF_OK: return "COMPLETE_QF_OK";
+ default: return "?";
+ }
+}
+
+void target_show_cmd(const char *ctxt, struct se_cmd *cmd)
+{
+ pr_debug("%s: still waiting for %s with tag %#llx; dir %s i_state %d t_tate %s len %d tgt_ref %d refcnt %d\n",
+ ctxt, cmd->se_cmd_flags & SCF_SCSI_TMR_CDB ? "tmf" : "cmd",
+ cmd->tag, data_dir_name(cmd->data_direction),
+ cmd->se_tfo->get_cmd_state(cmd), cmd_state_name(cmd->t_state),
+ cmd->data_length, atomic_read(&cmd->tgt_ref),
+ atomic_read(&cmd->cmd_kref.refcount));
+}
+
/* target_sess_cmd_list_set_waiting - Flag all commands in
* sess_cmd_list to complete cmd_wait_comp. Set
* sess_tearing_down so no more commands are queued.
@@ -3017,16 +3058,7 @@ static int __transport_check_aborted_status(struct se_cmd *cmd, int send_status)
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);
- cmd->se_tfo->queue_status(cmd);
- spin_lock_irq(&cmd->t_state_lock);
return 1;
}
@@ -3043,47 +3075,6 @@ int transport_check_aborted_status(struct se_cmd *cmd, int send_status)
}
EXPORT_SYMBOL(transport_check_aborted_status);
-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)) {
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- return;
- }
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-
- /*
- * If there are still expected incoming fabric WRITEs, we wait
- * until until they have completed before sending a TASK_ABORTED
- * response. This response with TASK_ABORTED status will be
- * queued back to fabric module by transport_check_aborted_status().
- */
- if (cmd->data_direction == DMA_TO_DEVICE) {
- if (cmd->se_tfo->write_pending_status(cmd) != 0) {
- spin_lock_irqsave(&cmd->t_state_lock, flags);
- if (cmd->se_cmd_flags & SCF_SEND_DELAYED_TAS) {
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- goto send_abort;
- }
- cmd->se_cmd_flags |= SCF_SEND_DELAYED_TAS;
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- return;
- }
- }
-send_abort:
- cmd->scsi_status = SAM_STAT_TASK_ABORTED;
-
- transport_lun_remove_cmd(cmd);
-
- pr_debug("Setting SAM_STAT_TASK_ABORTED status for CDB: 0x%02x, ITT: 0x%08llx\n",
- cmd->t_task_cdb[0], cmd->tag);
-
- trace_target_cmd_complete(cmd);
- cmd->se_tfo->queue_status(cmd);
-}
-
static void target_tmr_work(struct work_struct *work)
{
struct se_cmd *cmd = container_of(work, struct se_cmd, work);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index c84e5eecb94d..e5e0fd852ff5 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -444,6 +444,7 @@ struct se_cmd {
unsigned cmd_wait_set:1;
unsigned unknown_data_length:1;
bool state_active:1;
+ bool send_abort_response:1;
u64 tag; /* SAM command identifier aka task tag */
/* Delay for ALUA Active/NonOptimized state access in milliseconds */
int alua_nonop_delay;
--
2.11.0
--
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