scsi: iscsi: Use the session workqueue for recovery

Use the session workqueue for recovery and unbinding. If there are delays
during device blocking/cleanup then it will no longer affect other
sessions.

Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Chris Leech <[e-mail]>
Reviewed-by: Lee Duncan <[e-mail]>
Signed-off-by: Mike Christie <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/scsi_transport_iscsi.c

···
 };
 
 static atomic_t iscsi_session_nr; /* sysfs session id for next new session */
-static struct workqueue_struct *iscsi_eh_timer_workq;
 
 static struct workqueue_struct *iscsi_conn_cleanup_workq;
 
···
 	if (!cancel_work_sync(&session->block_work))
 		cancel_delayed_work_sync(&session->recovery_work);
 
-	queue_work(iscsi_eh_timer_workq, &session->unblock_work);
+	queue_work(session->workq, &session->unblock_work);
 	/*
 	 * Blocking the session can be done from any context so we only
 	 * queue the block work. Make sure the unblock work has completed
···
 	scsi_target_block(&session->dev);
 	ISCSI_DBG_TRANS_SESSION(session, "Completed SCSI target blocking\n");
 	if (session->recovery_tmo >= 0)
-		queue_delayed_work(iscsi_eh_timer_workq,
+		queue_delayed_work(session->workq,
 				   &session->recovery_work,
 				   session->recovery_tmo * HZ);
 }
 
 void iscsi_block_session(struct iscsi_cls_session *session)
 {
-	queue_work(iscsi_eh_timer_workq, &session->block_work);
+	queue_work(session->workq, &session->block_work);
 }
 EXPORT_SYMBOL_GPL(iscsi_block_session);
 
···
 		goto unregister_flashnode_bus;
 	}
 
-	iscsi_eh_timer_workq = alloc_workqueue("%s",
-			WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
-			1, "iscsi_eh");
-	if (!iscsi_eh_timer_workq) {
-		err = -ENOMEM;
-		goto release_nls;
-	}
-
 	iscsi_conn_cleanup_workq = alloc_workqueue("%s",
 			WQ_SYSFS | WQ_MEM_RECLAIM | WQ_UNBOUND, 0,
 			"iscsi_conn_cleanup");
 	if (!iscsi_conn_cleanup_workq) {
 		err = -ENOMEM;
-		goto destroy_wq;
+		goto release_nls;
 	}
 
 	return 0;
 
-destroy_wq:
-	destroy_workqueue(iscsi_eh_timer_workq);
 release_nls:
 	netlink_kernel_release(nls);
 unregister_flashnode_bus:
···
 static void __exit iscsi_transport_exit(void)
 {
 	destroy_workqueue(iscsi_conn_cleanup_workq);
-	destroy_workqueue(iscsi_eh_timer_workq);
 	netlink_kernel_release(nls);
 	bus_unregister(&iscsi_flashnode_bus);
 	transport_class_unregister(&iscsi_connection_class);