scsi: iscsi: Use system_unbound_wq for destroy_work

Use the system_unbound_wq for async session destruction. We don't need a
dedicated workqueue for async session destruction because:

 1. perf does not seem to be an issue since we only allow 1 active work.

 2. it does not have deps with other system works and we can run them in
    parallel with each other.

Link: https://lore.kernel.org/r/20210525181821.7617-6-michael.christie@oracle.com
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index d134156..2eb77f6 100644 (file)
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -95,8 +95,6 @@ static DECLARE_WORK(stop_conn_work, stop_conn_work_fn);
 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_destroy_workq;
-
 static DEFINE_IDA(iscsi_sess_ida);
 /*
  * list of registered transports and lock that must
@@ -3724,7 +3722,7 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
                        list_del_init(&session->sess_list);
                        spin_unlock_irqrestore(&sesslock, flags);
 
-                       queue_work(iscsi_destroy_workq, &session->destroy_work);
+                       queue_work(system_unbound_wq, &session->destroy_work);
                }
                break;
        case ISCSI_UEVENT_UNBIND_SESSION:
@@ -4820,18 +4818,8 @@ static __init int iscsi_transport_init(void)
                goto release_nls;
        }
 
-       iscsi_destroy_workq = alloc_workqueue("%s",
-                       WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
-                       1, "iscsi_destroy");
-       if (!iscsi_destroy_workq) {
-               err = -ENOMEM;
-               goto destroy_wq;
-       }
-
        return 0;
 
-destroy_wq:
-       destroy_workqueue(iscsi_eh_timer_workq);
 release_nls:
        netlink_kernel_release(nls);
 unregister_flashnode_bus:
@@ -4853,7 +4841,6 @@ unregister_transport_class:
 
 static void __exit iscsi_transport_exit(void)
 {
-       destroy_workqueue(iscsi_destroy_workq);
        destroy_workqueue(iscsi_eh_timer_workq);
        netlink_kernel_release(nls);
        bus_unregister(&iscsi_flashnode_bus);