target: Remove unnecessary se_task members
Christoph Hellwig [Wed, 12 Oct 2011 15:07:04 +0000 (11:07 -0400)]
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>

drivers/target/target_core_tmr.c
drivers/target/target_core_transport.c
include/target/target_core_base.h
include/target/target_core_transport.h

index b5c1864..b8a780f 100644 (file)
@@ -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);
 
index 165a60c..4a787a0 100644 (file)
@@ -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;
 
index 5e3dd14..45291b2 100644 (file)
@@ -409,15 +409,12 @@ struct se_task {
        u8              task_scsi_status;
        u8              task_flags;
        int             task_error_status;
-       bool            task_padded_sg;
        unsigned long long      task_lba;
-       u32             task_no;
        u32             task_sectors;
        u32             task_size;
        enum dma_data_direction task_data_direction;
        struct se_cmd *task_se_cmd;
        struct completion       task_stop_comp;
-       atomic_t        task_execute_queue;
        atomic_t        task_state_active;
        struct timer_list       task_timer;
        struct list_head t_list;
index c93cf0a..c5eb259 100644 (file)
@@ -135,6 +135,8 @@ extern void transport_add_task_to_execute_queue(struct se_task *,
                                                struct se_device *);
 extern void transport_remove_task_from_execute_queue(struct se_task *,
                                                struct se_device *);
+extern void __transport_remove_task_from_execute_queue(struct se_task *,
+                                               struct se_device *);
 unsigned char *transport_dump_cmd_direction(struct se_cmd *);
 extern void transport_dump_dev_state(struct se_device *, char *, int *);
 extern void transport_dump_dev_info(struct se_device *, struct se_lun *,