From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch adds SCF_EMULATE_QUEUE_FULL support using -EAGAIN failures
via transport_handle_queue_full() to signal queue full in completion
path TFO->queue_data_in() and TFO->queue_status() callbacks.
This is done using a new se_cmd->transport_qf_callback() to handle
the following queue full exception cases within target core:
*) TRANSPORT_COMPLETE_OK (for completion path queue full)
*) TRANSPORT_COMPLETE_QF_WP (for TRANSPORT_WRITE_PENDING queue full)
*) transport_send_check_condition_and_sense() failure paths in
transport_generic_request_failure() and transport_generic_complete_ok()
All logic is driven using se_device->qf_work_queue -> target_qf_do_work()
to to requeue outstanding se_cmd at the head of se_dev->queue_obj->qobj_list
for transport_processing_thread() execution.
Tested using tcm_qla2xxx with MAX_OUTSTANDING_COMMANDS=128 for FCP READ
to trigger the TRANSPORT_COMPLETE_OK queue full cases, and a simulated
TFO->write_pending() -EAGAIN failure to trigger TRANSPORT_COMPLETE_QF_WP.
Reported-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_transport.c | 194 +++++++++++++++++++++++++++++---
include/target/target_core_base.h | 9 ++
2 files changed, 188 insertions(+), 15 deletions(-)
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 1ae6eb7..056c4cb 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -204,6 +204,9 @@ static int transport_generic_write_pending(struct se_cmd *);
static int transport_processing_thread(void *param);
static int __transport_execute_tasks(struct se_device *dev);
static void transport_complete_task_attr(struct se_cmd *cmd);
+static int transport_complete_qf(struct se_cmd *cmd);
+static void transport_handle_queue_full(struct se_cmd *cmd,
+ struct se_device *dev, int (*qf_callback)(struct se_cmd *));
static void transport_direct_request_timeout(struct se_cmd *cmd);
static void transport_free_dev_tasks(struct se_cmd *cmd);
static u32 transport_allocate_tasks(struct se_cmd *cmd,
@@ -768,7 +771,11 @@ static void transport_add_cmd_to_queue(
}
spin_lock_irqsave(&qobj->cmd_queue_lock, flags);
- list_add_tail(&cmd->se_queue_node, &qobj->qobj_list);
+ if (cmd->se_cmd_flags & SCF_EMULATE_QUEUE_FULL) {
+ cmd->se_cmd_flags &= ~SCF_EMULATE_QUEUE_FULL;
+ list_add(&cmd->se_queue_node, &qobj->qobj_list);
+ } else
+ list_add_tail(&cmd->se_queue_node, &qobj->qobj_list);
atomic_inc(&cmd->t_transport_queue_active);
spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);
@@ -1102,6 +1109,40 @@ void transport_remove_task_from_execute_queue(
spin_unlock_irqrestore(&dev->execute_task_lock, flags);
}
+/*
+ * Handle QUEUE_FULL / -EAGAIN status
+ */
+
+static void target_qf_do_work(struct work_struct *work)
+{
+ struct se_device *dev = container_of(work, struct se_device,
+ qf_work_queue);
+ struct se_cmd *cmd, *cmd_tmp;
+
+ spin_lock_irq(&dev->qf_cmd_lock);
+ list_for_each_entry_safe(cmd, cmd_tmp, &dev->qf_cmd_list, se_qf_node) {
+
+ list_del(&cmd->se_qf_node);
+ atomic_dec(&dev->dev_qf_count);
+ smp_mb__after_atomic_dec();
+ spin_unlock_irq(&dev->qf_cmd_lock);
+
+ printk(KERN_INFO "Processing %s cmd: %p QUEUE_FULL in work queue"
+ " context: %s\n", cmd->se_tfo->get_fabric_name(), cmd,
+ (cmd->t_state == TRANSPORT_COMPLETE_OK) ? "COMPLETE_OK" :
+ (cmd->t_state == TRANSPORT_COMPLETE_QF_WP) ? "WRITE_PENDING"
+ : "UNKNOWN");
+ /*
+ * The SCF_EMULATE_QUEUE_FULL flag will be cleared once se_cmd
+ * has been added to head of queue
+ */
+ transport_add_cmd_to_queue(cmd, cmd->t_state);
+
+ spin_lock_irq(&dev->qf_cmd_lock);
+ }
+ spin_unlock_irq(&dev->qf_cmd_lock);
+}
+
unsigned char *transport_dump_cmd_direction(struct se_cmd *cmd)
{
switch (cmd->data_direction) {
@@ -1531,6 +1572,7 @@ struct se_device *transport_add_device_to_core_hba(
INIT_LIST_HEAD(&dev->delayed_cmd_list);
INIT_LIST_HEAD(&dev->ordered_cmd_list);
INIT_LIST_HEAD(&dev->state_task_list);
+ INIT_LIST_HEAD(&dev->qf_cmd_list);
spin_lock_init(&dev->execute_task_lock);
spin_lock_init(&dev->delayed_cmd_lock);
spin_lock_init(&dev->ordered_cmd_lock);
@@ -1541,6 +1583,7 @@ struct se_device *transport_add_device_to_core_hba(
spin_lock_init(&dev->dev_status_thr_lock);
spin_lock_init(&dev->se_port_lock);
spin_lock_init(&dev->se_tmr_lock);
+ spin_lock_init(&dev->qf_cmd_lock);
dev->queue_depth = dev_limits->queue_depth;
atomic_set(&dev->depth_left, dev->queue_depth);
@@ -1584,7 +1627,10 @@ struct se_device *transport_add_device_to_core_hba(
dev->transport->name);
goto out;
}
-
+ /*
+ * Setup work_queue for QUEUE_FULL
+ */
+ INIT_WORK(&dev->qf_work_queue, target_qf_do_work);
/*
* Preload the initial INQUIRY const values if we are doing
* anything virtual (IBLOCK, FILEIO, RAMDISK), but not for TCM/pSCSI
@@ -1697,6 +1743,7 @@ void transport_init_se_cmd(
INIT_LIST_HEAD(&cmd->se_lun_node);
INIT_LIST_HEAD(&cmd->se_delayed_node);
INIT_LIST_HEAD(&cmd->se_ordered_node);
+ INIT_LIST_HEAD(&cmd->se_qf_node);
INIT_LIST_HEAD(&cmd->t_mem_list);
INIT_LIST_HEAD(&cmd->t_mem_bidi_list);
@@ -2019,6 +2066,8 @@ static void transport_generic_request_failure(
int complete,
int sc)
{
+ int ret = 0;
+
DEBUG_GRF("-----[ Storage Engine Exception for cmd: %p ITT: 0x%08x"
" CDB: 0x%02x\n", cmd, cmd->se_tfo->get_task_tag(cmd),
cmd->t_task_cdb[0]);
@@ -2109,7 +2158,9 @@ static void transport_generic_request_failure(
cmd->orig_fe_lun, 0x2C,
ASCQ_2CH_PREVIOUS_RESERVATION_CONFLICT_STATUS);
- cmd->se_tfo->queue_status(cmd);
+ ret = cmd->se_tfo->queue_status(cmd);
+ if (ret == -EAGAIN)
+ goto queue_full;
goto check_stop;
case PYX_TRANSPORT_USE_SENSE_REASON:
/*
@@ -2126,13 +2177,22 @@ static void transport_generic_request_failure(
if (!sc)
transport_new_cmd_failure(cmd);
- else
- transport_send_check_condition_and_sense(cmd,
- cmd->scsi_sense_reason, 0);
+ else {
+ ret = transport_send_check_condition_and_sense(cmd,
+ cmd->scsi_sense_reason, 0);
+ if (ret == -EAGAIN)
+ goto queue_full;
+ }
+
check_stop:
transport_lun_remove_cmd(cmd);
if (!(transport_cmd_check_stop_to_fabric(cmd)))
;
+ return;
+
+queue_full:
+ cmd->t_state = TRANSPORT_COMPLETE_OK;
+ transport_handle_queue_full(cmd, cmd->se_dev, transport_complete_qf);
}
static void transport_direct_request_timeout(struct se_cmd *cmd)
@@ -3637,9 +3697,53 @@ static void transport_complete_task_attr(struct se_cmd *cmd)
wake_up_interruptible(&dev->dev_queue_obj.thread_wq);
}
+static int transport_complete_qf(struct se_cmd *cmd)
+{
+ int ret = 0;
+
+ if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE)
+ return cmd->se_tfo->queue_status(cmd);
+
+ switch (cmd->data_direction) {
+ case DMA_FROM_DEVICE:
+ ret = cmd->se_tfo->queue_data_in(cmd);
+ break;
+ case DMA_TO_DEVICE:
+ if (!list_empty(&cmd->t_mem_bidi_list)) {
+ ret = cmd->se_tfo->queue_data_in(cmd);
+ if (ret < 0)
+ return ret;
+ }
+ /* Fall through for DMA_TO_DEVICE */
+ case DMA_NONE:
+ ret = cmd->se_tfo->queue_status(cmd);
+ break;
+ default:
+ break;
+ }
+
+ return ret;
+}
+
+static void transport_handle_queue_full(
+ struct se_cmd *cmd,
+ struct se_device *dev,
+ int (*qf_callback)(struct se_cmd *))
+{
+ spin_lock_irq(&dev->qf_cmd_lock);
+ cmd->se_cmd_flags |= SCF_EMULATE_QUEUE_FULL;
+ cmd->transport_qf_callback = qf_callback;
+ list_add_tail(&cmd->se_qf_node, &cmd->se_dev->qf_cmd_list);
+ atomic_inc(&dev->dev_qf_count);
+ smp_mb__after_atomic_inc();
+ spin_unlock_irq(&cmd->se_dev->qf_cmd_lock);
+
+ schedule_work(&cmd->se_dev->qf_work_queue);
+}
+
static void transport_generic_complete_ok(struct se_cmd *cmd)
{
- int reason = 0;
+ int reason = 0, ret;
/*
* Check if we need to move delayed/dormant tasks from cmds on the
* delayed execution list after a HEAD_OF_QUEUE or ORDERED Task
@@ -3648,6 +3752,21 @@ static void transport_generic_complete_ok(struct se_cmd *cmd)
if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
transport_complete_task_attr(cmd);
/*
+ * Check to schedule QUEUE_FULL work, or execute an existing
+ * cmd->transport_qf_callback()
+ */
+ if (atomic_read(&cmd->se_dev->dev_qf_count) != 0)
+ schedule_work(&cmd->se_dev->qf_work_queue);
+
+ if (cmd->transport_qf_callback) {
+ ret = cmd->transport_qf_callback(cmd);
+ if (ret < 0)
+ goto queue_full;
+
+ cmd->transport_qf_callback = NULL;
+ goto done;
+ }
+ /*
* Check if we need to retrieve a sense buffer from
* the struct se_cmd in question.
*/
@@ -3660,8 +3779,11 @@ static void transport_generic_complete_ok(struct se_cmd *cmd)
* a non GOOD status.
*/
if (cmd->scsi_status) {
- transport_send_check_condition_and_sense(
+ ret = transport_send_check_condition_and_sense(
cmd, reason, 1);
+ if (ret == -EAGAIN)
+ goto queue_full;
+
transport_lun_remove_cmd(cmd);
transport_cmd_check_stop_to_fabric(cmd);
return;
@@ -3693,7 +3815,9 @@ static void transport_generic_complete_ok(struct se_cmd *cmd)
cmd->t_task_buf,
cmd->data_length);
- cmd->se_tfo->queue_data_in(cmd);
+ ret = cmd->se_tfo->queue_data_in(cmd);
+ if (ret == -EAGAIN)
+ goto queue_full;
break;
case DMA_TO_DEVICE:
spin_lock(&cmd->se_lun->lun_sep_lock);
@@ -3712,19 +3836,30 @@ static void transport_generic_complete_ok(struct se_cmd *cmd)
cmd->data_length;
}
spin_unlock(&cmd->se_lun->lun_sep_lock);
- cmd->se_tfo->queue_data_in(cmd);
+ ret = cmd->se_tfo->queue_data_in(cmd);
+ if (ret == -EAGAIN)
+ goto queue_full;
break;
}
/* Fall through for DMA_TO_DEVICE */
case DMA_NONE:
- cmd->se_tfo->queue_status(cmd);
+ ret = cmd->se_tfo->queue_status(cmd);
+ if (ret == -EAGAIN)
+ goto queue_full;
break;
default:
break;
}
+done:
transport_lun_remove_cmd(cmd);
transport_cmd_check_stop_to_fabric(cmd);
+ return;
+
+queue_full:
+ printk(KERN_INFO "Handling complete_ok QUEUE_FULL: se_cmd: %p,"
+ " data_direction: %d\n", cmd, cmd->data_direction);
+ transport_handle_queue_full(cmd, cmd->se_dev, transport_complete_qf);
}
static void transport_free_dev_tasks(struct se_cmd *cmd)
@@ -4866,6 +5001,11 @@ void transport_generic_process_write(struct se_cmd *cmd)
}
EXPORT_SYMBOL(transport_generic_process_write);
+static int transport_write_pending_qf(struct se_cmd *cmd)
+{
+ return cmd->se_tfo->write_pending(cmd);
+}
+
/* transport_generic_write_pending():
*
*
@@ -4878,6 +5018,17 @@ static int transport_generic_write_pending(struct se_cmd *cmd)
spin_lock_irqsave(&cmd->t_state_lock, flags);
cmd->t_state = TRANSPORT_WRITE_PENDING;
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
+ if (cmd->transport_qf_callback) {
+ ret = cmd->transport_qf_callback(cmd);
+ if (ret == -EAGAIN)
+ goto queue_full;
+ else if (ret < 0)
+ return ret;
+
+ cmd->transport_qf_callback = NULL;
+ return 0;
+ }
/*
* For the TCM control CDBs using a contiguous buffer, do the memcpy
* from the passed Linux/SCSI struct scatterlist located at
@@ -4903,10 +5054,19 @@ static int transport_generic_write_pending(struct se_cmd *cmd)
* frontend know that WRITE buffers are ready.
*/
ret = cmd->se_tfo->write_pending(cmd);
- if (ret < 0)
+ if (ret == -EAGAIN)
+ goto queue_full;
+ else if (ret < 0)
return ret;
return PYX_TRANSPORT_WRITE_PENDING;
+
+queue_full:
+ printk(KERN_INFO "Handling write_pending QUEUE__FULL: se_cmd: %p\n", cmd);
+ cmd->t_state = TRANSPORT_COMPLETE_QF_WP;
+ transport_handle_queue_full(cmd, cmd->se_dev,
+ transport_write_pending_qf);
+ return ret;
}
void transport_release_cmd(struct se_cmd *cmd)
@@ -5410,8 +5570,7 @@ int transport_send_check_condition_and_sense(
cmd->scsi_sense_length = TRANSPORT_SENSE_BUFFER + offset;
after_reason:
- cmd->se_tfo->queue_status(cmd);
- return 0;
+ return cmd->se_tfo->queue_status(cmd);
}
EXPORT_SYMBOL(transport_send_check_condition_and_sense);
@@ -5733,7 +5892,9 @@ get_cmd:
/* Fall through */
case TRANSPORT_NEW_CMD:
ret = transport_generic_new_cmd(cmd);
- if (ret < 0) {
+ if (ret == -EAGAIN)
+ break;
+ else if (ret < 0) {
cmd->transport_error_status = ret;
transport_generic_request_failure(cmd, NULL,
0, (cmd->data_direction !=
@@ -5763,6 +5924,9 @@ get_cmd:
transport_stop_all_task_timers(cmd);
transport_generic_request_timeout(cmd);
break;
+ case TRANSPORT_COMPLETE_QF_WP:
+ transport_generic_write_pending(cmd);
+ break;
default:
printk(KERN_ERR "Unknown t_state: %d deferred_t_state:"
" %d for ITT: 0x%08x i_state: %d on SE LUN:"
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 71abc4c..cd163dd 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -99,6 +99,7 @@ enum transport_state_table {
TRANSPORT_FREE = 15,
TRANSPORT_NEW_CMD_MAP = 16,
TRANSPORT_FREE_CMD_INTR = 17,
+ TRANSPORT_COMPLETE_QF_WP = 18,
};
/* Used for struct se_cmd->se_cmd_flags */
@@ -125,6 +126,7 @@ enum se_cmd_flags_table {
SCF_PASSTHROUGH_CONTIG_TO_SG = 0x00200000,
SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC = 0x00400000,
SCF_EMULATE_CDB_ASYNC = 0x01000000,
+ SCF_EMULATE_QUEUE_FULL = 0x02000000,
};
/* struct se_dev_entry->lun_flags and struct se_lun->lun_access */
@@ -466,6 +468,7 @@ struct se_cmd {
struct list_head se_delayed_node;
struct list_head se_ordered_node;
struct list_head se_lun_node;
+ struct list_head se_qf_node;
struct se_device *se_dev;
struct se_dev_entry *se_deve;
struct se_device *se_obj_ptr;
@@ -480,6 +483,8 @@ struct se_cmd {
void (*transport_split_cdb)(unsigned long long, u32 *, unsigned char *);
void (*transport_wait_for_tasks)(struct se_cmd *, int, int);
void (*transport_complete_callback)(struct se_cmd *);
+ int (*transport_qf_callback)(struct se_cmd *);
+
unsigned char *t_task_cdb;
unsigned char __t_task_cdb[TCM_MAX_COMMAND_SIZE];
unsigned long long t_task_lba;
@@ -743,6 +748,7 @@ struct se_device {
atomic_t dev_status_thr_count;
atomic_t dev_hoq_count;
atomic_t dev_ordered_sync;
+ atomic_t dev_qf_count;
struct se_obj dev_obj;
struct se_obj dev_access_obj;
struct se_obj dev_export_obj;
@@ -758,6 +764,7 @@ struct se_device {
spinlock_t dev_status_thr_lock;
spinlock_t se_port_lock;
spinlock_t se_tmr_lock;
+ spinlock_t qf_cmd_lock;
/* Used for legacy SPC-2 reservationsa */
struct se_node_acl *dev_reserved_node_acl;
/* Used for ALUA Logical Unit Group membership */
@@ -771,10 +778,12 @@ struct se_device {
struct task_struct *process_thread;
pid_t process_thread_pid;
struct task_struct *dev_mgmt_thread;
+ struct work_struct qf_work_queue;
struct list_head delayed_cmd_list;
struct list_head ordered_cmd_list;
struct list_head execute_task_list;
struct list_head state_task_list;
+ struct list_head qf_cmd_list;
/* Pointer to associated SE HBA */
struct se_hba *se_hba;
struct se_subsystem_dev *se_sub_dev;
--
1.7.6
--
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