target: Simplify LUN shutdown code

Instead of starting a thread from transport_clear_lun_ref() that
waits for LUN shutdown, wait in that function for LUN shutdown
to finish. Additionally, change the return type of
transport_clear_lun_ref() from int to void.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_device.c

@@ -928,7 +928,6 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
 
 	xcopy_lun = &dev->xcopy_lun;
 	xcopy_lun->lun_se_dev = dev;
-	init_completion(&xcopy_lun->lun_shutdown_comp);
 	spin_lock_init(&xcopy_lun->lun_sep_lock);
 	init_completion(&xcopy_lun->lun_ref_comp);
 

drivers/target/target_core_internal.h

@@ -108,7 +108,7 @@ int	transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int);
 int	transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int);
 int	transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int);
 bool	target_stop_cmd(struct se_cmd *cmd, unsigned long *flags);
-int	transport_clear_lun_ref(struct se_lun *);
+void	transport_clear_lun_ref(struct se_lun *);
 void	transport_send_task_abort(struct se_cmd *);
 sense_reason_t	target_cmd_size_check(struct se_cmd *cmd, unsigned int size);
 void	target_qf_do_work(struct work_struct *work);

drivers/target/target_core_tpg.c

@@ -494,7 +494,6 @@ static int core_tpg_setup_virtual_lun0(struct se_portal_group *se_tpg)
 
 	lun->unpacked_lun = 0;
 	atomic_set(&lun->lun_acl_count, 0);
-	init_completion(&lun->lun_shutdown_comp);
 	spin_lock_init(&lun->lun_sep_lock);
 	init_completion(&lun->lun_ref_comp);
 
@@ -606,7 +605,6 @@ struct se_lun *core_tpg_alloc_lun(
 	lun->unpacked_lun = unpacked_lun;
 	lun->lun_link_magic = SE_LUN_LINK_MAGIC;
 	atomic_set(&lun->lun_acl_count, 0);
-	init_completion(&lun->lun_shutdown_comp);
 	spin_lock_init(&lun->lun_sep_lock);
 	init_completion(&lun->lun_ref_comp);
 

drivers/target/target_core_transport.c

@@ -2596,31 +2596,10 @@ void target_wait_for_sess_cmds(struct se_session *se_sess)
 }
 EXPORT_SYMBOL(target_wait_for_sess_cmds);
 
-static int transport_clear_lun_ref_thread(void *p)
+void transport_clear_lun_ref(struct se_lun *lun)
 {
-	struct se_lun *lun = p;
-
 	percpu_ref_kill(&lun->lun_ref);
-
 	wait_for_completion(&lun->lun_ref_comp);
-	complete(&lun->lun_shutdown_comp);
-
-	return 0;
-}
-
-int transport_clear_lun_ref(struct se_lun *lun)
-{
-	struct task_struct *kt;
-
-	kt = kthread_run(transport_clear_lun_ref_thread, lun,
-			"tcm_cl_%u", lun->unpacked_lun);
-	if (IS_ERR(kt)) {
-		pr_err("Unable to start clear_lun thread\n");
-		return PTR_ERR(kt);
-	}
-	wait_for_completion(&lun->lun_shutdown_comp);
-
-	return 0;
 }
 
 /**

include/target/target_core_base.h

@@ -707,7 +707,6 @@ struct se_lun {
 	u32			lun_index;
 	atomic_t		lun_acl_count;
 	spinlock_t		lun_sep_lock;
-	struct completion	lun_shutdown_comp;
 	struct se_device	*lun_se_dev;
 	struct se_port		*lun_sep;
 	struct config_group	lun_group;