target: Remove unnecessary se_task members

This is a squashed version of the following unnecessary se_task structure
member removal patches:

target: remove the task_execute_queue field in se_task

    Instead of using a separate flag we can simply do list_emptry checks
    on t_execute_list if we make sure to always use list_del_init to remove
    a task from the list.  Also factor some duplicate code into a new
    __transport_remove_task_from_execute_queue helper.

target: remove the read-only task_no field in se_task

    The task_no field never was initialized and only used in debug printks,
    so kill it.

target: remove the task_padded_sg field in se_task

    This field is only check in one place and not actually needed there.

    Rationale:
    - transport_do_task_sg_chain asserts that we have task_sg_chaining
      set early on
    - we only make use of the sg_prev_nents field we calculate based on it
      if there is another sg list that gets chained onto this one, which
      never happens for the last (or only) task.

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

2 files changed, 26 insertions, 40 deletions

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index b5c18648fa2..b8a780fff36 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -226,11 +226,8 @@ static void core_tmr_drain_task_list(
                 /*
                  * Remove from task execute list before processing drain_task_list
                  */
-                if (atomic_read(&task->task_execute_queue) != 0) {
-                        list_del(&task->t_execute_list);
-                        atomic_set(&task->task_execute_queue, 0);
-                        atomic_dec(&dev->execute_tasks);
-                }
+                if (!list_empty(&task->t_execute_list))
+                        __transport_remove_task_from_execute_queue(task, dev);
         }
         spin_unlock_irqrestore(&dev->execute_task_lock, flags);
 
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 165a60c875a..4a787a0ab06 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -915,38 +915,36 @@ static void transport_add_tasks_from_cmd(struct se_cmd *cmd)
 
         spin_lock_irqsave(&dev->execute_task_lock, flags);
         list_for_each_entry(task, &cmd->t_task_list, t_list) {
-                if (atomic_read(&task->task_execute_queue))
+                if (!list_empty(&task->t_execute_list))
                         continue;
                 /*
                  * __transport_add_task_to_execute_queue() handles the
                  * SAM Task Attribute emulation if enabled
                  */
                 __transport_add_task_to_execute_queue(task, task_prev, dev);
-                atomic_set(&task->task_execute_queue, 1);
                 task_prev = task;
         }
         spin_unlock_irqrestore(&dev->execute_task_lock, flags);
 }
 
-/*      transport_remove_task_from_execute_queue():
- *
- *
- */
+void __transport_remove_task_from_execute_queue(struct se_task *task,
+                struct se_device *dev)
+{
+        list_del_init(&task->t_execute_list);
+        atomic_dec(&dev->execute_tasks);
+}
+
 void transport_remove_task_from_execute_queue(
         struct se_task *task,
         struct se_device *dev)
 {
         unsigned long flags;
 
-        if (atomic_read(&task->task_execute_queue) == 0) {
-                dump_stack();
+        if (WARN_ON(list_empty(&task->t_execute_list)))
                 return;
-        }
 
         spin_lock_irqsave(&dev->execute_task_lock, flags);
-        list_del(&task->t_execute_list);
-        atomic_set(&task->task_execute_queue, 0);
-        atomic_dec(&dev->execute_tasks);
+        __transport_remove_task_from_execute_queue(task, dev);
         spin_unlock_irqrestore(&dev->execute_task_lock, flags);
 }
 
@@ -1787,8 +1785,7 @@ static int transport_stop_tasks_for_cmd(struct se_cmd *cmd)
         spin_lock_irqsave(&cmd->t_state_lock, flags);
         list_for_each_entry_safe(task, task_tmp,
                                 &cmd->t_task_list, t_list) {
-                pr_debug("task_no[%d] - Processing task %p\n",
-                                task->task_no, task);
+                pr_debug("Processing task %p\n", task);
                 /*
                  * If the struct se_task has not been sent and is not active,
                  * remove the struct se_task from the execution queue.
@@ -1799,8 +1796,7 @@ static int transport_stop_tasks_for_cmd(struct se_cmd *cmd)
                         transport_remove_task_from_execute_queue(task,
                                         cmd->se_dev);
 
-                        pr_debug("task_no[%d] - Removed from execute queue\n",
-                                task->task_no);
+                        pr_debug("Task %p removed from execute queue\n", task);
                         spin_lock_irqsave(&cmd->t_state_lock, flags);
                         continue;
                 }
@@ -1814,17 +1810,15 @@ static int transport_stop_tasks_for_cmd(struct se_cmd *cmd)
                         spin_unlock_irqrestore(&cmd->t_state_lock,
                                         flags);
 
-                        pr_debug("task_no[%d] - Waiting to complete\n",
-                                task->task_no);
+                        pr_debug("Task %p waiting to complete\n", task);
                         wait_for_completion(&task->task_stop_comp);
-                        pr_debug("task_no[%d] - Stopped successfully\n",
-                                task->task_no);
+                        pr_debug("Task %p stopped successfully\n", task);
 
                         spin_lock_irqsave(&cmd->t_state_lock, flags);
                         atomic_dec(&cmd->t_task_cdbs_left);
                         task->task_flags &= ~(TF_ACTIVE | TF_REQUEST_STOP);
                 } else {
-                        pr_debug("task_no[%d] - Did nothing\n", task->task_no);
+                        pr_debug("Task %p - did nothing\n", task);
                         ret++;
                 }
 
@@ -2347,9 +2341,7 @@ check_depth:
         }
         task = list_first_entry(&dev->execute_task_list,
                                 struct se_task, t_execute_list);
-        list_del(&task->t_execute_list);
-        atomic_set(&task->task_execute_queue, 0);
-        atomic_dec(&dev->execute_tasks);
+        __transport_remove_task_from_execute_queue(task, dev);
         spin_unlock_irq(&dev->execute_task_lock);
 
         atomic_dec(&dev->depth_left);
@@ -2681,9 +2673,9 @@ static int transport_get_sense_data(struct se_cmd *cmd)
 
                 sense_buffer = dev->transport->get_sense_buffer(task);
                 if (!sense_buffer) {
-                        pr_err("ITT[0x%08x]_TASK[%d]: Unable to locate"
+                        pr_err("ITT[0x%08x]_TASK[%p]: Unable to locate"
                                 " sense buffer for task with sense\n",
-                                cmd->se_tfo->get_task_tag(cmd), task->task_no);
+                                cmd->se_tfo->get_task_tag(cmd), task);
                         continue;
                 }
                 spin_unlock_irqrestore(&cmd->t_state_lock, flags);
@@ -3897,15 +3889,13 @@ void transport_do_task_sg_chain(struct se_cmd *cmd)
                 /*
                  * For the padded tasks, use the extra SGL vector allocated
                  * in transport_allocate_data_tasks() for the sg_prev_nents
-                 * offset into sg_chain() above..  The last task of a
-                 * multi-task list, or a single task will not have
-                 * task->task_sg_padded set..
+                 * offset into sg_chain() above.
+                 *
+                 * We do not need the padding for the last task (or a single
+                 * task), but in that case we will never use the sg_prev_nents
+                 * value below which would be incorrect.
                  */
-                if (task->task_padded_sg)
-                        sg_prev_nents = (task->task_sg_nents + 1);
-                else
-                        sg_prev_nents = task->task_sg_nents;
-
+                sg_prev_nents = (task->task_sg_nents + 1);
                 sg_prev = task->task_sg;
         }
         /*
@@ -3992,7 +3982,6 @@ static int transport_allocate_data_tasks(
                  */
                 if (cmd->se_tfo->task_sg_chaining && (i < (task_count - 1))) {
                         task_sg_nents_padded = (task->task_sg_nents + 1);
-                        task->task_padded_sg = 1;
                 } else
                         task_sg_nents_padded = task->task_sg_nents;