target: replace the processing thread with a TMR work queue

The last functionality of the target processing thread is offloading possibly
long running task management requests from the submitter context.  To keep
TMR semantics the same we need a single threaded ordered queue, which can
be provided by a per-device workqueue with the right flags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 11052b2..4f4f042 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -147,7 +147,6 @@
 	TRANSPORT_WRITE_PENDING	= 3,
 	TRANSPORT_PROCESSING	= 5,
 	TRANSPORT_COMPLETE	= 6,
-	TRANSPORT_PROCESS_TMR	= 9,
 	TRANSPORT_ISTATE_PROCESSING = 11,
 	TRANSPORT_COMPLETE_QF_WP = 18,
 	TRANSPORT_COMPLETE_QF_OK = 19,
@@ -464,13 +463,6 @@
 	struct t10_reservation_ops pr_ops;
 };
 
-struct se_queue_obj {
-	atomic_t		queue_cnt;
-	spinlock_t		cmd_queue_lock;
-	struct list_head	qobj_list;
-	wait_queue_head_t	thread_wq;
-};
-
 struct se_tmr_req {
 	/* Task Management function to be performed */
 	u8			function;
@@ -527,7 +519,6 @@
 	/* Only used for internal passthrough and legacy TCM fabric modules */
 	struct se_session	*se_sess;
 	struct se_tmr_req	*se_tmr_req;
-	struct list_head	se_queue_node;
 	struct list_head	se_cmd_list;
 	struct completion	cmd_wait_comp;
 	struct kref		cmd_kref;
@@ -774,7 +765,6 @@
 	struct se_obj		dev_obj;
 	struct se_obj		dev_access_obj;
 	struct se_obj		dev_export_obj;
-	struct se_queue_obj	dev_queue_obj;
 	spinlock_t		delayed_cmd_lock;
 	spinlock_t		execute_task_lock;
 	spinlock_t		dev_reservation_lock;
@@ -790,8 +780,7 @@
 	struct t10_pr_registration *dev_pr_res_holder;
 	struct list_head	dev_sep_list;
 	struct list_head	dev_tmr_list;
-	/* Pointer to descriptor for processing thread */
-	struct task_struct	*process_thread;
+	struct workqueue_struct *tmr_wq;
 	struct work_struct	qf_work_queue;
 	struct list_head	delayed_cmd_list;
 	struct list_head	state_list;