net/smc: introduce bookkeeping of SMCD link groups

If the ism module is unloaded return control from exit routine only,
if all link groups are freed.
If an IB device is thrown away return control from device removal only,
if all link groups belonging to this device are freed.
A counters for the total number of SMCD link groups per ISM device is
introduced. ism module unloading continues only if the total number of
SMCD link groups for all ISM devices is zero. ISM device
removal continues only it the total number of SMCD link groups per ISM
device has decreased to zero.
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/smc.h

@@ -79,6 +79,8 @@ struct smcd_dev {
 	bool pnetid_by_user;
 	struct list_head lgr_list;
 	spinlock_t lgr_lock;
+	atomic_t lgr_cnt;
+	wait_queue_head_t lgrs_deleted;
 	u8 going_away : 1;
 };
 

net/smc/smc_core.c

@@ -276,6 +276,7 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini)
 		lgr_list = &ini->ism_dev->lgr_list;
 		lgr_lock = &lgr->smcd->lgr_lock;
 		lgr->peer_shutdown = 0;
+		atomic_inc(&ini->ism_dev->lgr_cnt);
 	} else {
 		/* SMC-R specific settings */
 		get_device(&ini->ib_dev->ibdev->dev);
@@ -486,6 +487,8 @@ static void smc_lgr_free(struct smc_link_group *lgr)
 			smc_ism_put_vlan(lgr->smcd, lgr->vlan_id);
 			put_device(&lgr->smcd->dev);
 		}
+		if (!atomic_dec_return(&lgr->smcd->lgr_cnt))
+			wake_up(&lgr->smcd->lgrs_deleted);
 	} else {
 		smc_link_clear(&lgr->lnk[SMC_SINGLE_LINK]);
 		put_device(&lgr->lnk[SMC_SINGLE_LINK].smcibdev->ibdev->dev);
@@ -685,6 +688,9 @@ void smc_smcd_terminate_all(struct smcd_dev *smcd)
 		list_del_init(&lgr->list);
 		__smc_lgr_terminate(lgr, false);
 	}
+
+	if (atomic_read(&smcd->lgr_cnt))
+		wait_event(smcd->lgrs_deleted, !atomic_read(&smcd->lgr_cnt));
 }
 
 /* Determine vlan of internal TCP socket.

net/smc/smc_ism.c

@@ -302,6 +302,7 @@ struct smcd_dev *smcd_alloc_dev(struct device *parent, const char *name,
 	spin_lock_init(&smcd->lgr_lock);
 	INIT_LIST_HEAD(&smcd->vlan);
 	INIT_LIST_HEAD(&smcd->lgr_list);
+	init_waitqueue_head(&smcd->lgrs_deleted);
 	smcd->event_wq = alloc_ordered_workqueue("ism_evt_wq-%s)",
 						 WQ_MEM_RECLAIM, name);
 	if (!smcd->event_wq) {