s390/cio/chp : Remove deprecated create_singlethread_workqueue

The workqueue "chp_wq" is involved in performing pending
configure tasks for channel paths.

It has a single work item(&cfg_work) and hence doesn't require
ordering. Also, it is not being used on a memory reclaim path.
Hence, the singlethreaded workqueue has been replaced with the use of
system_wq.

System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 9 deletions

diff --git a/drivers/s390/cio/chp.c b/drivers/s390/cio/chp.c
index d3b72eab2b8f..e96aced58627 100644
--- a/drivers/s390/cio/chp.c
+++ b/drivers/s390/cio/chp.c
@@ -47,8 +47,6 @@ static DEFINE_MUTEX(info_lock);
 /* Time after which channel-path status may be outdated. */
 static unsigned long chp_info_expires;
 
-/* Workqueue to perform pending configure tasks. */
-static struct workqueue_struct *chp_wq;
 static struct work_struct cfg_work;
 
 /* Wait queue for configure completion events. */
@@ -717,7 +715,7 @@ static void cfg_func(struct work_struct *work)
                 wake_up_interruptible(&cfg_wait_queue);
                 return;
         }
-        queue_work(chp_wq, &cfg_work);
+        schedule_work(&cfg_work);
 }
 
 /**
@@ -735,7 +733,7 @@ void chp_cfg_schedule(struct chp_id chpid, int configure)
         cfg_set_task(chpid, configure ? cfg_configure : cfg_deconfigure);
         cfg_busy = 1;
         mutex_unlock(&cfg_lock);
-        queue_work(chp_wq, &cfg_work);
+        schedule_work(&cfg_work);
 }
 
 /**
@@ -769,11 +767,6 @@ static int __init chp_init(void)
         ret = crw_register_handler(CRW_RSC_CPATH, chp_process_crw);
         if (ret)
                 return ret;
-        chp_wq = create_singlethread_workqueue("cio_chp");
-        if (!chp_wq) {
-                crw_unregister_handler(CRW_RSC_CPATH);
-                return -ENOMEM;
-        }
         INIT_WORK(&cfg_work, cfg_func);
         init_waitqueue_head(&cfg_wait_queue);
         if (info_update())