RDMA/mlx4: Avoid flush_scheduled_work() usage

Flushing system-wide workqueues is dangerous and will be forbidden.
Replace system_wq with local cm_wq.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Tetsuo Handa <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/hw/mlx4/cm.c

···
 	union ib_gid primary_path_sgid;
 };
 
+static struct workqueue_struct *cm_wq;
 
 static void set_local_comm_id(struct ib_mad *mad, u32 cm_id)
 {
···
 	/*make sure that there is no schedule inside the scheduled work.*/
 	if (!sriov->is_going_down && !id->scheduled_delete) {
 		id->scheduled_delete = 1;
-		schedule_delayed_work(&id->timeout, CM_CLEANUP_CACHE_TIMEOUT);
+		queue_delayed_work(cm_wq, &id->timeout, CM_CLEANUP_CACHE_TIMEOUT);
 	} else if (id->scheduled_delete) {
 		/* Adjust timeout if already scheduled */
-		mod_delayed_work(system_wq, &id->timeout, CM_CLEANUP_CACHE_TIMEOUT);
+		mod_delayed_work(cm_wq, &id->timeout, CM_CLEANUP_CACHE_TIMEOUT);
 	}
 	spin_unlock_irqrestore(&sriov->going_down_lock, flags);
 	spin_unlock(&sriov->id_map_lock);
···
 			ret =  xa_err(item);
 		else
 			/* If a retry, adjust delayed work */
-			mod_delayed_work(system_wq, &item->timeout, CM_CLEANUP_CACHE_TIMEOUT);
+			mod_delayed_work(cm_wq, &item->timeout, CM_CLEANUP_CACHE_TIMEOUT);
 		goto err_or_exists;
 	}
 	xa_unlock(&sriov->xa_rej_tmout);
···
 		return xa_err(old);
 	}
 
-	schedule_delayed_work(&item->timeout, CM_CLEANUP_CACHE_TIMEOUT);
+	queue_delayed_work(cm_wq, &item->timeout, CM_CLEANUP_CACHE_TIMEOUT);
 
 	return 0;
 
···
 	xa_lock(&sriov->xa_rej_tmout);
 	xa_for_each(&sriov->xa_rej_tmout, id, item) {
 		if (slave < 0 || slave == item->slave) {
-			mod_delayed_work(system_wq, &item->timeout, 0);
+			mod_delayed_work(cm_wq, &item->timeout, 0);
 			flush_needed = true;
 			++cnt;
 		}
···
 	xa_unlock(&sriov->xa_rej_tmout);
 
 	if (flush_needed) {
-		flush_scheduled_work();
+		flush_workqueue(cm_wq);
 		pr_debug("Deleted %d entries in xarray for slave %d during cleanup\n",
 			 cnt, slave);
 	}
···
 	spin_unlock(&sriov->id_map_lock);
 
 	if (need_flush)
-		flush_scheduled_work(); /* make sure all timers were flushed */
+		flush_workqueue(cm_wq); /* make sure all timers were flushed */
 
 	/* now, remove all leftover entries from databases*/
 	spin_lock(&sriov->id_map_lock);
···
 	}
 
 	rej_tmout_xa_cleanup(sriov, slave);
+}
+
+int mlx4_ib_cm_init(void)
+{
+	cm_wq = alloc_workqueue("mlx4_ib_cm", 0, 0);
+	if (!cm_wq)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void mlx4_ib_cm_destroy(void)
+{
+	destroy_workqueue(cm_wq);
 }

drivers/infiniband/hw/mlx4/main.c

···
 	if (!wq)
 		return -ENOMEM;
 
-	err = mlx4_ib_mcg_init();
+	err = mlx4_ib_cm_init();
 	if (err)
 		goto clean_wq;
+
+	err = mlx4_ib_mcg_init();
+	if (err)
+		goto clean_cm;
 
 	err = mlx4_register_interface(&mlx4_ib_interface);
 	if (err)
···
 clean_mcg:
 	mlx4_ib_mcg_destroy();
 
+clean_cm:
+	mlx4_ib_cm_destroy();
+
 clean_wq:
 	destroy_workqueue(wq);
 	return err;
···
 {
 	mlx4_unregister_interface(&mlx4_ib_interface);
 	mlx4_ib_mcg_destroy();
+	mlx4_ib_cm_destroy();
 	destroy_workqueue(wq);
 }
 

drivers/infiniband/hw/mlx4/mlx4_ib.h

···
 int mlx4_ib_umem_calc_optimal_mtt_size(struct ib_umem *umem, u64 start_va,
 				       int *num_of_mtts);
 
+int mlx4_ib_cm_init(void);
+void mlx4_ib_cm_destroy(void);
+
 #endif /* MLX4_IB_H */