block/rnbd-clt: Avoid flush_workqueue(system_long_wq) usage

Flushing system-wide workqueues is dangerous and will be forbidden.

Replace system_long_wq with local rnbd_clt_wq.

Link: https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Santosh Kumar Pradhan <santosh.pradhan@ionos.com>
Link: https://lore.kernel.org/r/20220413123420.66470-1-jinpu.wang@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
index d178be1..409c76b 100644 (file)
--- a/drivers/block/rnbd/rnbd-clt.c
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -25,6 +25,7 @@ static int rnbd_client_major;
 static DEFINE_IDA(index_ida);
 static DEFINE_MUTEX(sess_lock);
 static LIST_HEAD(sess_list);
+static struct workqueue_struct *rnbd_clt_wq;
 
 /*
  * Maximum number of partitions an instance can have.
@@ -1759,12 +1760,12 @@ static void rnbd_destroy_sessions(void)
                         * procedure takes minutes.
                         */
                        INIT_WORK(&dev->unmap_on_rmmod_work, unmap_device_work);
-                       queue_work(system_long_wq, &dev->unmap_on_rmmod_work);
+                       queue_work(rnbd_clt_wq, &dev->unmap_on_rmmod_work);
                }
                rnbd_clt_put_sess(sess);
        }
        /* Wait for all scheduled unmap works */
-       flush_workqueue(system_long_wq);
+       flush_workqueue(rnbd_clt_wq);
        WARN_ON(!list_empty(&sess_list));
 }
 
@@ -1789,6 +1790,14 @@ static int __init rnbd_client_init(void)
                pr_err("Failed to load module, creating sysfs device files failed, err: %d\n",
                       err);
                unregister_blkdev(rnbd_client_major, "rnbd");
+               return err;
+       }
+       rnbd_clt_wq = alloc_workqueue("rnbd_clt_wq", 0, 0);
+       if (!rnbd_clt_wq) {
+               pr_err("Failed to load module, alloc_workqueue failed.\n");
+               rnbd_clt_destroy_sysfs_files();
+               unregister_blkdev(rnbd_client_major, "rnbd");
+               err = -ENOMEM;
        }
 
        return err;
@@ -1799,6 +1808,7 @@ static void __exit rnbd_client_exit(void)
        rnbd_destroy_sessions();
        unregister_blkdev(rnbd_client_major, "rnbd");
        ida_destroy(&index_ida);
+       destroy_workqueue(rnbd_clt_wq);
 }
 
 module_init(rnbd_client_init);