qla2x00t-32gbit, target: Avoid that qlt_free_session_done() hangs

Waiting for a long time inside a work item callback function is not a good
idea. Split qlt_free_session_done() in two functions and call the second
half asynchronously instead of waiting inside qlt_free_session_done().


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@8184 d57e44dd-8a1f-0410-8b47-8ef2f437770f

qla2x00t-32gbit/qla2x00-target/README

@@ -68,32 +68,3 @@ Call Trace:
  [<ffffffff8159c459>] ? retint_restore_args+0x13/0x43
  [<ffffffff810b2480>] ? kthread+0x0/0xc0
  [<ffffffff8159cc40>] ? child_rip+0x0/0x30
-
-When using RHEL 6 unloading this driver triggers a deadlock:
-
-INFO: task events/0:35 blocked for more than 120 seconds.
-      Not tainted 2.6.32-754.11.1.el6.x86_64.debug #1
-"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
-events/0      D ffff880077e24408 12408    35      2 0x00000000
- ffff88007e02fa60 0000000000000046 0000000000000000 7fffffffffffffff
- 7fffffffffffffff 00000365a5588f80 ffff88007e028a80 ffff88000d7d93d8
- 0000000100346a5e 00000000000003c8 ffff88007e029040 ffff88007e02ffd8
-Call Trace:
- [<ffffffff8158f775>] schedule_timeout+0x265/0x330
- [<ffffffff8158f29f>] ? wait_for_common+0x4f/0x180
- [<ffffffff8158f29f>] ? wait_for_common+0x4f/0x180
- [<ffffffff810737a0>] ? default_wake_function+0x0/0x20
- [<ffffffff8158f37b>] wait_for_common+0x12b/0x180
- [<ffffffff810737a0>] ? default_wake_function+0x0/0x20
- [<ffffffff8158f4ad>] wait_for_completion+0x1d/0x20
- [<ffffffffa0714946>] ? qlt_free_session_done+0x1d6/0x930 [qla2xxx_scst]
- [<ffffffffa0714770>] ? qlt_free_session_done+0x0/0x930 [qla2xxx_scst]
- [<ffffffff810ab2ee>] ? worker_thread+0x21e/0x3f0
- [<ffffffff810ab29b>] ? worker_thread+0x1cb/0x3f0
- [<ffffffff810b29b0>] ? autoremove_wake_function+0x0/0x40
- [<ffffffff810ab0d0>] ? worker_thread+0x0/0x3f0
- [<ffffffff810b2520>] ? kthread+0xa0/0xc0
- [<ffffffff8159cc60>] ? child_rip+0x20/0x30
- [<ffffffff8159c459>] ? retint_restore_args+0x13/0x43
- [<ffffffff810b2480>] ? kthread+0x0/0xc0
- [<ffffffff8159cc40>] ? child_rip+0x0/0x30

qla2x00t-32gbit/qla_def.h

@@ -2393,7 +2393,6 @@ typedef struct fc_port {
 #define NVME_FLAG_RESETTING 1
 
 	struct fc_port *conflict;
-	unsigned char logout_completed;
 	int generation;
 
 	struct se_session *se_sess;
@@ -2401,8 +2400,9 @@ typedef struct fc_port {
 	struct qla_tgt *tgt;
 	unsigned long expires;
 	struct list_head del_list_entry;
-	struct work_struct free_work;
 	struct work_struct reg_work;
+	struct work_struct post_logout_work;
+	struct work_struct finish_logout_work;
 	uint64_t jiffies_at_registration;
 	struct qlt_plogi_ack_t *plogi_link[QLT_PLOGI_LINK_MAX];
 	struct completion *unreg_done;

qla2x00t-32gbit/qla_init.c

@@ -224,7 +224,6 @@ qla2x00_async_login(struct scsi_qla_host *vha, fc_port_t *fcport,
 		goto done;
 
 	fcport->flags |= FCF_ASYNC_SENT;
-	fcport->logout_completed = 0;
 
 	fcport->disc_state = DSC_LOGIN_PEND;
 	sp->type = SRB_LOGIN_CMD;
@@ -1065,7 +1064,6 @@ qla24xx_async_prli(struct scsi_qla_host *vha, fc_port_t *fcport)
 		return rval;
 
 	fcport->flags |= FCF_ASYNC_SENT;
-	fcport->logout_completed = 0;
 
 	sp->type = SRB_PRLI_CMD;
 	sp->name = "prli";
@@ -4724,6 +4722,8 @@ qla2x00_alloc_fcport(scsi_qla_host_t *vha, gfp_t flags)
 
 	INIT_WORK(&fcport->del_work, qla24xx_delete_sess_fn);
 	INIT_WORK(&fcport->reg_work, qla_register_fcport_fn);
+	INIT_WORK(&fcport->post_logout_work, qlt_post_logout);
+	INIT_WORK(&fcport->finish_logout_work, qlt_finish_logout);
 	INIT_LIST_HEAD(&fcport->gnl_entry);
 	INIT_LIST_HEAD(&fcport->list);
 

qla2x00t-32gbit/qla_nvme.c

@@ -564,10 +564,8 @@ static void qla_nvme_remoteport_delete(struct nvme_fc_remote_port *rport)
 	}
 	complete(&fcport->nvme_del_done);
 
-	if (!test_bit(UNLOADING, &fcport->vha->dpc_flags)) {
-		INIT_WORK(&fcport->free_work, qlt_free_session_done);
-		schedule_work(&fcport->free_work);
-	}
+	if (!test_bit(UNLOADING, &fcport->vha->dpc_flags))
+		schedule_work(&fcport->post_logout_work);
 
 	fcport->nvme_flag &= ~NVME_FLAG_DELETING;
 	ql_log(ql_log_info, fcport->vha, 0x2110,

qla2x00t-32gbit/qla_target.c

@@ -698,7 +698,8 @@ void qla24xx_do_nack_work(struct scsi_qla_host *vha, struct qla_work_evt *e)
 	case SRB_NACK_PRLI:
 		t = e->u.nack.fcport;
 		flush_work(&t->del_work);
-		flush_work(&t->free_work);
+		flush_work(&t->post_logout_work);
+		flush_work(&t->finish_logout_work);
 		mutex_lock(&vha->vha_tgt.tgt_mutex);
 		t = qlt_create_sess(vha, e->u.nack.fcport, 0);
 		mutex_unlock(&vha->vha_tgt.tgt_mutex);
@@ -969,16 +970,13 @@ qlt_send_first_logo(struct scsi_qla_host *vha, qlt_port_logo_t *logo)
 	    logo->cmd_count, res);
 }
 
-void qlt_free_session_done(struct work_struct *work)
+void qlt_post_logout(struct work_struct *work)
 {
 	struct fc_port *sess = container_of(work, struct fc_port,
-	    free_work);
-	struct qla_tgt *tgt = sess->tgt;
+					    post_logout_work);
 	struct scsi_qla_host *vha = sess->vha;
 	struct qla_hw_data *ha = vha->hw;
-	unsigned long flags;
 	bool logout_started = false;
-	scsi_qla_host_t *base_vha;
 	struct qlt_plogi_ack_t *own =
 		sess->plogi_link[QLT_PLOGI_LINK_SAME_WWN];
 
@@ -1036,22 +1034,19 @@ void qlt_free_session_done(struct work_struct *work)
 	if (sess->se_sess != NULL)
 		ha->tgt.tgt_ops->free_session(sess);
 
-	if (logout_started) {
-		bool traced = false;
+	if (!logout_started)
+		qlt_finish_logout(&sess->finish_logout_work);
+}
 
-		while (!READ_ONCE(sess->logout_completed)) {
-			if (!traced) {
-				ql_dbg(ql_dbg_tgt_mgt, vha, 0xf086,
-					"%s: waiting for sess %p logout\n",
-					__func__, sess);
-				traced = true;
-			}
-			msleep(100);
-		}
-
-		ql_dbg(ql_dbg_disc, vha, 0xf087,
-		    "%s: sess %p logout completed\n", __func__, sess);
-	}
+void qlt_finish_logout(struct work_struct *work)
+{
+	struct fc_port *sess = container_of(work, struct fc_port,
+					    finish_logout_work);
+	struct qla_tgt *tgt = sess->tgt;
+	struct scsi_qla_host *vha = sess->vha;
+	struct qla_hw_data *ha = vha->hw;
+	scsi_qla_host_t *base_vha;
+	unsigned long flags;
 
 	if (sess->logo_ack_needed) {
 		sess->logo_ack_needed = 0;
@@ -1088,7 +1083,8 @@ void qlt_free_session_done(struct work_struct *work)
 		struct qlt_plogi_ack_t *con =
 		    sess->plogi_link[QLT_PLOGI_LINK_CONFLICT];
 		struct imm_ntfy_from_isp *iocb;
-		own = sess->plogi_link[QLT_PLOGI_LINK_SAME_WWN];
+		struct qlt_plogi_ack_t *own =
+		    sess->plogi_link[QLT_PLOGI_LINK_SAME_WWN];
 
 		if (con) {
 			iocb = &con->iocb;
@@ -1186,8 +1182,7 @@ void qlt_unreg_sess(struct fc_port *sess)
 		sess->nvme_flag |= NVME_FLAG_DELETING;
 		schedule_work(&sess->nvme_del_work);
 	} else {
-		INIT_WORK(&sess->free_work, qlt_free_session_done);
-		schedule_work(&sess->free_work);
+		schedule_work(&sess->post_logout_work);
 	}
 }
 EXPORT_SYMBOL(qlt_unreg_sess);
@@ -1395,7 +1390,6 @@ static struct fc_port *qlt_create_sess(
 	 */
 	sess->logout_on_delete = 1;
 	sess->keep_nport_handle = 0;
-	sess->logout_completed = 0;
 
 	if (ha->tgt.tgt_ops->check_initiator_node_acl(vha,
 	    &fcport->port_name[0], sess) < 0) {
@@ -4734,7 +4728,7 @@ void qlt_logo_completion_handler(fc_port_t *fcport, int rc)
 			fcport->d_id.b.al_pa, rc);
 	}
 
-	fcport->logout_completed = 1;
+	schedule_work(&fcport->finish_logout_work);
 }
 
 /*

qla2x00t-32gbit/qla_target.h

@@ -1069,7 +1069,9 @@ extern void qlt_fc_port_deleted(struct scsi_qla_host *, fc_port_t *, int);
 extern int __init qlt_init(void);
 extern void qlt_exit(void);
 extern void qlt_update_vp_map(struct scsi_qla_host *, int);
-extern void qlt_free_session_done(struct work_struct *);
+extern void qlt_post_logout(struct work_struct *);
+extern void qlt_finish_logout(struct work_struct *work);
+
 /*
  * This macro is used during early initializations when host->active_mode
  * is not set. Right now, ha value is ignored.