Revert "scst: Rework the code for waiting until an I/O context is ready"

This reverts commit 32cadc07df.

The only reason for this revert is to avoid merge conflicts with trunk
commit 0a4bce0392.

scst/include/scst.h

@@ -2275,7 +2275,6 @@ struct scst_cmd_threads {
 	int io_context_refcnt;
 
 	bool io_context_ready;
-	wait_queue_head_t io_context_wait;
 
 	/* io_context_mutex protects io_context and io_context_refcnt. */
 	struct mutex io_context_mutex;

scst/src/scst_lib.c

@@ -4725,7 +4725,13 @@ found:
 			t->acg_dev->acg->acg_io_grouping_type);
 	} else {
 		res = t;
-		scst_wait_ioctx(res->active_cmd_threads);
+		if (!*(volatile bool *)&res->active_cmd_threads->io_context_ready) {
+			TRACE_DBG("IO context for t %p not yet "
+				"initialized, waiting...", t);
+			msleep(100);
+			goto found;
+		}
+		smp_rmb();
 		TRACE_DBG("Going to share IO context %p (res %p, ini %s, "
 			"dev %s, cmd_threads %p, grouping type %d)",
 			res->active_cmd_threads->io_context, res,

scst/src/scst_main.c

@@ -1925,7 +1925,12 @@ out_wait:
 		 * Wait for io_context gets initialized to avoid possible races
 		 * for it from the sharing it tgt_devs.
 		 */
-		scst_wait_ioctx(cmd_threads);
+		while (!*(volatile bool *)&cmd_threads->io_context_ready) {
+			TRACE_DBG("Waiting for io_context for cmd_threads %p "
+				"initialized", cmd_threads);
+			msleep(50);
+		}
+		smp_rmb();
 	}
 
 	if (res != 0)
@@ -2176,7 +2181,6 @@ void scst_init_threads(struct scst_cmd_threads *cmd_threads)
 	INIT_LIST_HEAD(&cmd_threads->threads_list);
 	mutex_init(&cmd_threads->io_context_mutex);
 	spin_lock_init(&cmd_threads->thr_lock);
-	init_waitqueue_head(&cmd_threads->io_context_wait);
 
 	mutex_lock(&scst_cmd_threads_mutex);
 	list_add_tail(&cmd_threads->lists_list_entry,

scst/src/scst_priv.h

@@ -215,8 +215,6 @@ struct scst_cmd_thread_t {
 	bool		 being_stopped;
 };
 
-void scst_wait_ioctx(struct scst_cmd_threads *tp);
-
 static inline bool scst_set_io_context(struct scst_cmd *cmd,
 	struct io_context **old)
 {

scst/src/scst_targ.c

@@ -4714,20 +4714,6 @@ int scst_init_thread(void *arg)
 	return 0;
 }
 
-/**
- * scst_wait_ioctx_timeout() - wait until an I/O context becomes available
- * @tp: Thread pool to wait on.
- *
- * Returns the number of jiffies remaining if the I/O context became available
- * in time and zero if the I/O context did not become available in time.
- */
-void scst_wait_ioctx(struct scst_cmd_threads *tp)
-{
-	wait_event(tp->io_context_wait,
-		   *(volatile bool *)&tp->io_context_ready);
-	smp_rmb();
-}
-
 /**
  * scst_ioctx_get() - Associate an I/O context with a thread.
  *
@@ -4795,8 +4781,7 @@ See "http://lkml.org/lkml/2012/7/17/515" for more details.
 
 	smp_wmb();
 	p_cmd_threads->io_context_ready = true;
-
-	wake_up_all(&p_cmd_threads->io_context_wait);
+	return;
 }
 
 /**