[SCSI] libsas: trim sas_task of slow path infrastructure

The timer and the completion are only used for slow path tasks (smp, and
lldd tmfs), yet we incur the allocation space and cpu setup time for
every fast path task.

Cc: Xiangliang Yu <yuxiangl@marvell.com>
Acked-by: Jack Wang <jack_wang@usish.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

3 files changed, 37 insertions, 14 deletions

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 879dbbe69799..efc6e72f09f3 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -51,14 +51,14 @@ static void smp_task_timedout(unsigned long _task)
                 task->task_state_flags |= SAS_TASK_STATE_ABORTED;
         spin_unlock_irqrestore(&task->task_state_lock, flags);
 
-        complete(&task->completion);
+        complete(&task->slow_task->completion);
 }
 
 static void smp_task_done(struct sas_task *task)
 {
-        if (!del_timer(&task->timer))
+        if (!del_timer(&task->slow_task->timer))
                 return;
-        complete(&task->completion);
+        complete(&task->slow_task->completion);
 }
 
 /* Give it some long enough timeout. In seconds. */
@@ -79,7 +79,7 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
                         break;
                 }
 
-                task = sas_alloc_task(GFP_KERNEL);
+                task = sas_alloc_slow_task(GFP_KERNEL);
                 if (!task) {
                         res = -ENOMEM;
                         break;
@@ -91,20 +91,20 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
 
                 task->task_done = smp_task_done;
 
-                task->timer.data = (unsigned long) task;
-                task->timer.function = smp_task_timedout;
-                task->timer.expires = jiffies + SMP_TIMEOUT*HZ;
-                add_timer(&task->timer);
+                task->slow_task->timer.data = (unsigned long) task;
+                task->slow_task->timer.function = smp_task_timedout;
+                task->slow_task->timer.expires = jiffies + SMP_TIMEOUT*HZ;
+                add_timer(&task->slow_task->timer);
 
                 res = i->dft->lldd_execute_task(task, 1, GFP_KERNEL);
 
                 if (res) {
-                        del_timer(&task->timer);
+                        del_timer(&task->slow_task->timer);
                         SAS_DPRINTK("executing SMP task failed:%d\n", res);
                         break;
                 }
 
-                wait_for_completion(&task->completion);
+                wait_for_completion(&task->slow_task->completion);
                 res = -ECOMM;
                 if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
                         SAS_DPRINTK("smp task timed out or aborted\n");
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 1bbab3d94a20..014297c05880 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -48,18 +48,37 @@ struct sas_task *sas_alloc_task(gfp_t flags)
                 INIT_LIST_HEAD(&task->list);
                 spin_lock_init(&task->task_state_lock);
                 task->task_state_flags = SAS_TASK_STATE_PENDING;
-                init_timer(&task->timer);
-                init_completion(&task->completion);
         }
 
         return task;
 }
 EXPORT_SYMBOL_GPL(sas_alloc_task);
 
+struct sas_task *sas_alloc_slow_task(gfp_t flags)
+{
+        struct sas_task *task = sas_alloc_task(flags);
+        struct sas_task_slow *slow = kmalloc(sizeof(*slow), flags);
+
+        if (!task || !slow) {
+                if (task)
+                        kmem_cache_free(sas_task_cache, task);
+                kfree(slow);
+                return NULL;
+        }
+
+        task->slow_task = slow;
+        init_timer(&slow->timer);
+        init_completion(&slow->completion);
+
+        return task;
+}
+EXPORT_SYMBOL_GPL(sas_alloc_slow_task);
+
 void sas_free_task(struct sas_task *task)
 {
         if (task) {
                 BUG_ON(!list_empty(&task->list));
+                kfree(task->slow_task);
                 kmem_cache_free(sas_task_cache, task);
         }
 }
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 676414859872..6e795a174a12 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -1134,9 +1134,13 @@ void sas_task_abort(struct sas_task *task)
 
         /* Escape for libsas internal commands */
         if (!sc) {
-                if (!del_timer(&task->timer))
+                struct sas_task_slow *slow = task->slow_task;
+
+                if (!slow)
+                        return;
+                if (!del_timer(&slow->timer))
                         return;
-                task->timer.function(task->timer.data);
+                slow->timer.function(slow->timer.data);
                 return;
         }