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>

3 files changed, 0 insertions, 175 deletions

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 1511a2ff86d8..e0c1e8a8dd4e 100644
--- a/drivers/target/target_core_configfs.c
+++ b/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,
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 81352b7f9130..f870c3bcfd82 100644
--- a/drivers/target/target_core_device.c
+++ b/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)
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 5027619552f0..d75255804481 100644
--- a/drivers/target/target_core_transport.c
+++ b/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;
 
@@ -749,35 +726,11 @@ 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
          * device queue depending upon int success.
@@ -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..