[PATCH 05/10] target/core: Use system workqueues for TMF

[PATCH 05/10] target/core: Use system workqueues for TMF

[Bart Van Assche]

A quote from SAM-5: "The order in which task management requests
are processed is not specified by the SCSI architecture model.
The SCSI architecture model does not require in-order delivery of
such task management requests or processing by the task manager
in the order received. To guarantee the processing order of task
management requests referencing sent to a specific logical unit,
an application client should not have more than one such task
management request pending to that logical unit." This means that
it is safe to use the system workqueues instead of tmr_wq for
processing TMFs. An intended side effect of this patch is that it
enables concurrent processing of TMFs.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Mike Christie <mchristi@redhat.com>
Cc: David Disseldorp <ddiss@suse.de>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/target/target_core_device.c    | 16 ----------------
 drivers/target/target_core_transport.c |  2 +-
 include/target/target_core_base.h      |  1 -
 3 files changed, 1 insertion(+), 18 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index c6b1122ee097..d452d2059946 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -985,18 +985,6 @@ int target_configure_device(struct se_device *dev)
 	if (ret)
 		goto out_destroy_device;
 
-	/*
-	 * Startup the struct se_device processing thread
-	 */
-	dev->tmr_wq = alloc_workqueue("tmr-%s", WQ_MEM_RECLAIM | WQ_UNBOUND, 1,
-				      dev->transport->name);
-	if (!dev->tmr_wq) {
-		pr_err("Unable to create tmr workqueue for %s\n",
-			dev->transport->name);
-		ret = -ENOMEM;
-		goto out_free_alua;
-	}
-
 	/*
 	 * Setup work_queue for QUEUE_FULL
 	 */
@@ -1025,8 +1013,6 @@ int target_configure_device(struct se_device *dev)
 
 	return 0;
 
-out_free_alua:
-	core_alua_free_lu_gp_mem(dev);
 out_destroy_device:
 	dev->transport->destroy_device(dev);
 out_free_index:
@@ -1045,8 +1031,6 @@ void target_free_device(struct se_device *dev)
 	WARN_ON(!list_empty(&dev->dev_sep_list));
 
 	if (target_dev_configured(dev)) {
-		destroy_workqueue(dev->tmr_wq);
-
 		dev->transport->destroy_device(dev);
 
 		mutex_lock(&device_mutex);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 3c4335e56f08..cf76d3709683 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -3411,7 +3411,7 @@ int transport_generic_handle_tmr(
 	}
 
 	INIT_WORK(&cmd->work, target_tmr_work);
-	queue_work(cmd->se_dev->tmr_wq, &cmd->work);
+	schedule_work(&cmd->work);
 	return 0;
 }
 EXPORT_SYMBOL(transport_generic_handle_tmr);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 067da330ed9c..67130841d421 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -794,7 +794,6 @@ struct se_device {
 	struct t10_pr_registration *dev_pr_res_holder;
 	struct list_head	dev_sep_list;
 	struct list_head	dev_tmr_list;
-	struct workqueue_struct *tmr_wq;
 	struct work_struct	qf_work_queue;
 	struct list_head	delayed_cmd_list;
 	struct list_head	state_list;
-- 
2.19.1.930.g4563a0d9d0-goog