target: Remove legacy se_task->task_timer and associated logic

This patch removes the legacy usage of se_task->task_timer and associated
infrastructure that originally was used as a way to help manage buggy backend
SCSI LLDs that in certain cases would never return back an outstanding task.

This includes the removal of target_complete_timeout_work(), timeout logic
from transport_complete_task(), transport_task_timeout_handler(),
transport_start_task_timer(), the per device task_timeout configfs attribute,
and all task_timeout associated structure members and defines in
target_core_base.h

This is being removed in preparation to make transport_complete_task() run
in lock-less mode.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_configfs.c

@@ -716,9 +716,6 @@ SE_DEV_ATTR_RO(hw_queue_depth);
 DEF_DEV_ATTRIB(queue_depth);
 SE_DEV_ATTR(queue_depth, S_IRUGO | S_IWUSR);
 
-DEF_DEV_ATTRIB(task_timeout);
-SE_DEV_ATTR(task_timeout, S_IRUGO | S_IWUSR);
-
 DEF_DEV_ATTRIB(max_unmap_lba_count);
 SE_DEV_ATTR(max_unmap_lba_count, S_IRUGO | S_IWUSR);
 
@@ -752,7 +749,6 @@ static struct configfs_attribute *target_core_dev_attrib_attrs[] = {
 	&target_core_dev_attrib_optimal_sectors.attr,
 	&target_core_dev_attrib_hw_queue_depth.attr,
 	&target_core_dev_attrib_queue_depth.attr,
-	&target_core_dev_attrib_task_timeout.attr,
 	&target_core_dev_attrib_max_unmap_lba_count.attr,
 	&target_core_dev_attrib_max_unmap_block_desc_count.attr,
 	&target_core_dev_attrib_unmap_granularity.attr,

drivers/target/target_core_device.c

@@ -914,21 +914,6 @@ void se_dev_set_default_attribs(
 	dev->se_sub_dev->se_dev_attrib.queue_depth = dev_limits->queue_depth;
 }
 
-int se_dev_set_task_timeout(struct se_device *dev, u32 task_timeout)
-{
-	if (task_timeout > DA_TASK_TIMEOUT_MAX) {
-		pr_err("dev[%p]: Passed task_timeout: %u larger then"
-			" DA_TASK_TIMEOUT_MAX\n", dev, task_timeout);
-		return -EINVAL;
-	} else {
-		dev->se_sub_dev->se_dev_attrib.task_timeout = task_timeout;
-		pr_debug("dev[%p]: Set SE Device task_timeout: %u\n",
-			dev, task_timeout);
-	}
-
-	return 0;
-}
-
 int se_dev_set_max_unmap_lba_count(
 	struct se_device *dev,
 	u32 max_unmap_lba_count)

drivers/target/target_core_transport.c

@@ -75,7 +75,6 @@ static int __transport_execute_tasks(struct se_device *dev);
 static void transport_complete_task_attr(struct se_cmd *cmd);
 static void transport_handle_queue_full(struct se_cmd *cmd,
 		struct se_device *dev);
-static void transport_direct_request_timeout(struct se_cmd *cmd);
 static void transport_free_dev_tasks(struct se_cmd *cmd);
 static int transport_generic_get_mem(struct se_cmd *cmd);
 static void transport_put_cmd(struct se_cmd *cmd);
@@ -682,26 +681,6 @@ void transport_complete_sync_cache(struct se_cmd *cmd, int good)
 }
 EXPORT_SYMBOL(transport_complete_sync_cache);
 
-static void target_complete_timeout_work(struct work_struct *work)
-{
-	struct se_cmd *cmd = container_of(work, struct se_cmd, work);
-	unsigned long flags;
-
-	/*
-	 * Reset cmd->t_se_count to allow transport_put_cmd()
-	 * to allow last call to free memory resources.
-	 */
-	spin_lock_irqsave(&cmd->t_state_lock, flags);
-	if (atomic_read(&cmd->t_transport_timeout) > 1) {
-		int tmp = (atomic_read(&cmd->t_transport_timeout) - 1);
-
-		atomic_sub(tmp, &cmd->t_se_count);
-	}
-	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-
-	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);
@@ -726,8 +705,6 @@ void transport_complete_task(struct se_task *task, int success)
 	if (dev)
 		atomic_inc(&dev->depth_left);
 
-	del_timer(&task->task_timer);
-
 	spin_lock_irqsave(&cmd->t_state_lock, flags);
 	task->task_flags &= ~TF_ACTIVE;
 
@@ -749,34 +726,10 @@ void transport_complete_task(struct se_task *task, int success)
 	 * to complete for an exception condition
 	 */
 	if (task->task_flags & TF_REQUEST_STOP) {
-		/*
-		 * Decrement cmd->t_se_count if this task had
-		 * previously thrown its timeout exception handler.
-		 */
-		if (task->task_flags & TF_TIMEOUT) {
-			atomic_dec(&cmd->t_se_count);
-			task->task_flags &= ~TF_TIMEOUT;
-		}
 		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-
 		complete(&task->task_stop_comp);
 		return;
 	}
-	/*
-	 * If the task's timeout handler has fired, use the t_task_cdbs_timeout
-	 * left counter to determine when the struct se_cmd is ready to be queued to
-	 * the processing thread.
-	 */
-	if (task->task_flags & TF_TIMEOUT) {
-		if (!atomic_dec_and_test(&cmd->t_task_cdbs_timeout_left)) {
-			spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-			return;
-		}
-		INIT_WORK(&cmd->work, target_complete_timeout_work);
-		goto out_queue;
-	}
-	atomic_dec(&cmd->t_task_cdbs_timeout_left);
-
 	/*
 	 * Decrement the outstanding t_task_cdbs_left count.  The last
 	 * struct se_task from struct se_cmd will complete itself into the
@@ -800,7 +753,6 @@ void transport_complete_task(struct se_task *task, int success)
 		INIT_WORK(&cmd->work, target_complete_ok_work);
 	}
 
-out_queue:
 	cmd->t_state = TRANSPORT_COMPLETE;
 	atomic_set(&cmd->t_transport_active, 1);
 	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
@@ -1519,7 +1471,6 @@ transport_generic_get_task(struct se_cmd *cmd,
 	INIT_LIST_HEAD(&task->t_list);
 	INIT_LIST_HEAD(&task->t_execute_list);
 	INIT_LIST_HEAD(&task->t_state_list);
-	init_timer(&task->task_timer);
 	init_completion(&task->task_stop_comp);
 	task->task_se_cmd = cmd;
 	task->task_data_direction = data_direction;
@@ -1787,7 +1738,6 @@ bool target_stop_task(struct se_task *task, unsigned long *flags)
 		spin_unlock_irqrestore(&cmd->t_state_lock, *flags);
 
 		pr_debug("Task %p waiting to complete\n", task);
-		del_timer_sync(&task->task_timer);
 		wait_for_completion(&task->task_stop_comp);
 		pr_debug("Task %p stopped successfully\n", task);
 
@@ -1876,7 +1826,6 @@ static void transport_generic_request_failure(
 		transport_complete_task_attr(cmd);
 
 	if (complete) {
-		transport_direct_request_timeout(cmd);
 		cmd->transport_error_status = PYX_TRANSPORT_LU_COMM_FAILURE;
 	}
 
@@ -1979,25 +1928,6 @@ queue_full:
 	transport_handle_queue_full(cmd, cmd->se_dev);
 }
 
-static void transport_direct_request_timeout(struct se_cmd *cmd)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&cmd->t_state_lock, flags);
-	if (!atomic_read(&cmd->t_transport_timeout)) {
-		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-		return;
-	}
-	if (atomic_read(&cmd->t_task_cdbs_timeout_left)) {
-		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-		return;
-	}
-
-	atomic_sub(atomic_read(&cmd->t_transport_timeout),
-		   &cmd->t_se_count);
-	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-}
-
 static inline u32 transport_lba_21(unsigned char *cdb)
 {
 	return ((cdb[1] & 0x1f) << 16) | (cdb[2] << 8) | cdb[3];
@@ -2040,80 +1970,6 @@ static void transport_set_supported_SAM_opcode(struct se_cmd *se_cmd)
 	spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
 }
 
-/*
- * Called from interrupt context.
- */
-static void transport_task_timeout_handler(unsigned long data)
-{
-	struct se_task *task = (struct se_task *)data;
-	struct se_cmd *cmd = task->task_se_cmd;
-	unsigned long flags;
-
-	pr_debug("transport task timeout fired! task: %p cmd: %p\n", task, cmd);
-
-	spin_lock_irqsave(&cmd->t_state_lock, flags);
-
-	/*
-	 * Determine if transport_complete_task() has already been called.
-	 */
-	if (!(task->task_flags & TF_ACTIVE)) {
-		pr_debug("transport task: %p cmd: %p timeout !TF_ACTIVE\n",
-			 task, cmd);
-		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-		return;
-	}
-
-	atomic_inc(&cmd->t_se_count);
-	atomic_inc(&cmd->t_transport_timeout);
-	cmd->t_tasks_failed = 1;
-
-	task->task_flags |= TF_TIMEOUT;
-	task->task_error_status = PYX_TRANSPORT_TASK_TIMEOUT;
-	task->task_scsi_status = 1;
-
-	if (task->task_flags & TF_REQUEST_STOP) {
-		pr_debug("transport task: %p cmd: %p timeout TF_REQUEST_STOP"
-				" == 1\n", task, cmd);
-		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-		complete(&task->task_stop_comp);
-		return;
-	}
-
-	if (!atomic_dec_and_test(&cmd->t_task_cdbs_left)) {
-		pr_debug("transport task: %p cmd: %p timeout non zero"
-				" t_task_cdbs_left\n", task, cmd);
-		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-		return;
-	}
-	pr_debug("transport task: %p cmd: %p timeout ZERO t_task_cdbs_left\n",
-			task, cmd);
-
-	INIT_WORK(&cmd->work, target_complete_failure_work);
-	cmd->t_state = TRANSPORT_COMPLETE;
-	atomic_set(&cmd->t_transport_active, 1);
-	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-
-	queue_work(target_completion_wq, &cmd->work);
-}
-
-static void transport_start_task_timer(struct se_task *task)
-{
-	struct se_device *dev = task->task_se_cmd->se_dev;
-	int timeout;
-
-	/*
-	 * If the task_timeout is disabled, exit now.
-	 */
-	timeout = dev->se_sub_dev->se_dev_attrib.task_timeout;
-	if (!timeout)
-		return;
-
-	task->task_timer.expires = (get_jiffies_64() + timeout * HZ);
-	task->task_timer.data = (unsigned long) task;
-	task->task_timer.function = transport_task_timeout_handler;
-	add_timer(&task->task_timer);
-}
-
 static inline int transport_tcq_window_closed(struct se_device *dev)
 {
 	if (dev->dev_tcq_window_closed++ <
@@ -2296,7 +2152,6 @@ check_depth:
 	    cmd->t_task_list_num)
 		atomic_set(&cmd->t_transport_sent, 1);
 
-	transport_start_task_timer(task);
 	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 	/*
 	 * The struct se_cmd->transport_emulate_cdb() function pointer is used
@@ -2310,7 +2165,6 @@ check_depth:
 			spin_lock_irqsave(&cmd->t_state_lock, flags);
 			task->task_flags &= ~TF_ACTIVE;
 			spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-			del_timer_sync(&task->task_timer);
 			atomic_set(&cmd->t_transport_sent, 0);
 			transport_stop_tasks_for_cmd(cmd);
 			atomic_inc(&dev->depth_left);
@@ -2350,7 +2204,6 @@ check_depth:
 			spin_lock_irqsave(&cmd->t_state_lock, flags);
 			task->task_flags &= ~TF_ACTIVE;
 			spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-			del_timer_sync(&task->task_timer);
 			atomic_set(&cmd->t_transport_sent, 0);
 			transport_stop_tasks_for_cmd(cmd);
 			atomic_inc(&dev->depth_left);
@@ -3543,14 +3396,6 @@ static void transport_free_dev_tasks(struct se_cmd *cmd)
 	while (!list_empty(&dispose_list)) {
 		task = list_first_entry(&dispose_list, struct se_task, t_list);
 
-		/*
-		 * We already cancelled all pending timers in
-		 * transport_complete_task, but that was just a pure del_timer,
-		 * so do a full del_timer_sync here to make sure any handler
-		 * that was running at that point has finished execution.
-		 */
-		del_timer_sync(&task->task_timer);
-
 		if (task->task_sg != cmd->t_data_sg &&
 		    task->task_sg != cmd->t_bidi_data_sg)
 			kfree(task->task_sg);
@@ -4007,7 +3852,6 @@ int transport_generic_new_cmd(struct se_cmd *cmd)
 	cmd->t_task_list_num = (task_cdbs + task_cdbs_bidi);
 	atomic_set(&cmd->t_task_cdbs_left, cmd->t_task_list_num);
 	atomic_set(&cmd->t_task_cdbs_ex_left, cmd->t_task_list_num);
-	atomic_set(&cmd->t_task_cdbs_timeout_left, cmd->t_task_list_num);
 
 	/*
 	 * For WRITEs, let the fabric know its buffer is ready..

include/target/target_core_base.h

@@ -75,8 +75,7 @@ enum transport_tpg_type_table {
 enum se_task_flags {
 	TF_ACTIVE		= (1 << 0),
 	TF_SENT			= (1 << 1),
-	TF_TIMEOUT		= (1 << 2),
-	TF_REQUEST_STOP		= (1 << 3),
+	TF_REQUEST_STOP		= (1 << 2),
 };
 
 /* Special transport agnostic struct se_cmd->t_states */
@@ -404,7 +403,6 @@ struct se_task {
 	int			task_error_status;
 	enum dma_data_direction	task_data_direction;
 	atomic_t		task_state_active;
-	struct timer_list	task_timer;
 	struct list_head	t_list;
 	struct list_head	t_execute_list;
 	struct list_head	t_state_list;
@@ -469,7 +467,6 @@ struct se_cmd {
 	atomic_t		t_se_count;
 	atomic_t		t_task_cdbs_left;
 	atomic_t		t_task_cdbs_ex_left;
-	atomic_t		t_task_cdbs_timeout_left;
 	atomic_t		t_task_cdbs_sent;
 	atomic_t		t_transport_aborted;
 	atomic_t		t_transport_active;
@@ -477,7 +474,6 @@ struct se_cmd {
 	atomic_t		t_transport_queue_active;
 	atomic_t		t_transport_sent;
 	atomic_t		t_transport_stop;
-	atomic_t		t_transport_timeout;
 	atomic_t		transport_dev_active;
 	atomic_t		transport_lun_active;
 	atomic_t		transport_lun_fe_stop;
@@ -646,7 +642,6 @@ struct se_dev_attrib {
 	u32		optimal_sectors;
 	u32		hw_queue_depth;
 	u32		queue_depth;
-	u32		task_timeout;
 	u32		max_unmap_lba_count;
 	u32		max_unmap_block_desc_count;
 	u32		unmap_granularity;

include/target/target_core_transport.h

@@ -22,10 +22,9 @@
 #define PYX_TRANSPORT_LU_COMM_FAILURE		-7
 #define PYX_TRANSPORT_UNKNOWN_MODE_PAGE		-8
 #define PYX_TRANSPORT_WRITE_PROTECTED		-9
-#define PYX_TRANSPORT_TASK_TIMEOUT		-10
-#define PYX_TRANSPORT_RESERVATION_CONFLICT	-11
-#define PYX_TRANSPORT_ILLEGAL_REQUEST		-12
-#define PYX_TRANSPORT_USE_SENSE_REASON		-13
+#define PYX_TRANSPORT_RESERVATION_CONFLICT	-10
+#define PYX_TRANSPORT_ILLEGAL_REQUEST		-11
+#define PYX_TRANSPORT_USE_SENSE_REASON		-12
 
 #ifndef SAM_STAT_RESERVATION_CONFLICT
 #define SAM_STAT_RESERVATION_CONFLICT		0x18
@@ -38,13 +37,6 @@
 #define TRANSPORT_PLUGIN_VHBA_PDEV		2
 #define TRANSPORT_PLUGIN_VHBA_VDEV		3
 
-/* For SE OBJ Plugins, in seconds */
-#define TRANSPORT_TIMEOUT_TUR			10
-#define TRANSPORT_TIMEOUT_TYPE_DISK		60
-#define TRANSPORT_TIMEOUT_TYPE_ROM		120
-#define TRANSPORT_TIMEOUT_TYPE_TAPE		600
-#define TRANSPORT_TIMEOUT_TYPE_OTHER		300
-
 /*
  * struct se_subsystem_dev->su_dev_flags
 */
@@ -61,8 +53,6 @@
 #define DF_SPC2_RESERVATIONS_WITH_ISID		0x00000004
 
 /* struct se_dev_attrib sanity values */
-/* 10 Minutes */
-#define DA_TASK_TIMEOUT_MAX			600
 /* Default max_unmap_lba_count */
 #define DA_MAX_UNMAP_LBA_COUNT			0
 /* Default max_unmap_block_desc_count */