net/smc: introduce bookkeeping of SMCR link groups

If the smc 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.
Counters for the total number of SMCR link groups and for the total
number of SMCR links per IB device are introduced. smc module unloading
continues only if the total number of SMCR link groups is zero. IB device
removal continues only it the total number of SMCR links per IB 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>

net/smc/af_smc.c

@@ -2038,22 +2038,28 @@ static int __init smc_init(void)
 	if (rc)
 		goto out_pernet_subsys;
 
+	rc = smc_core_init();
+	if (rc) {
+		pr_err("%s: smc_core_init fails with %d\n", __func__, rc);
+		goto out_pnet;
+	}
+
 	rc = smc_llc_init();
 	if (rc) {
 		pr_err("%s: smc_llc_init fails with %d\n", __func__, rc);
-		goto out_pnet;
+		goto out_core;
 	}
 
 	rc = smc_cdc_init();
 	if (rc) {
 		pr_err("%s: smc_cdc_init fails with %d\n", __func__, rc);
-		goto out_pnet;
+		goto out_core;
 	}
 
 	rc = proto_register(&smc_proto, 1);
 	if (rc) {
 		pr_err("%s: proto_register(v4) fails with %d\n", __func__, rc);
-		goto out_pnet;
+		goto out_core;
 	}
 
 	rc = proto_register(&smc_proto6, 1);
@@ -2085,6 +2091,8 @@ static int __init smc_init(void)
 	proto_unregister(&smc_proto6);
 out_proto:
 	proto_unregister(&smc_proto);
+out_core:
+	smc_core_exit();
 out_pnet:
 	smc_pnet_exit();
 out_pernet_subsys:
@@ -2095,10 +2103,10 @@ static int __init smc_init(void)
 
 static void __exit smc_exit(void)
 {
-	smc_core_exit();
 	static_branch_disable(&tcp_have_smc);
-	smc_ib_unregister_client();
 	sock_unregister(PF_SMC);
+	smc_core_exit();
+	smc_ib_unregister_client();
 	proto_unregister(&smc_proto6);
 	proto_unregister(&smc_proto);
 	smc_pnet_exit();

net/smc/smc_core.c

@@ -13,6 +13,7 @@
 #include <linux/if_vlan.h>
 #include <linux/random.h>
 #include <linux/workqueue.h>
+#include <linux/wait.h>
 #include <net/tcp.h>
 #include <net/sock.h>
 #include <rdma/ib_verbs.h>
@@ -39,6 +40,9 @@ static struct smc_lgr_list smc_lgr_list = {	/* established link groups */
 	.num = 0,
 };
 
+static atomic_t lgr_cnt;		/* number of existing link groups */
+static DECLARE_WAIT_QUEUE_HEAD(lgrs_deleted);
+
 static void smc_buf_free(struct smc_link_group *lgr, bool is_rmb,
 			 struct smc_buf_desc *buf_desc);
 
@@ -319,6 +323,8 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini)
 		rc = smc_wr_create_link(lnk);
 		if (rc)
 			goto destroy_qp;
+		atomic_inc(&lgr_cnt);
+		atomic_inc(&ini->ib_dev->lnk_cnt);
 	}
 	smc->conn.lgr = lgr;
 	spin_lock_bh(lgr_lock);
@@ -406,6 +412,8 @@ static void smc_link_clear(struct smc_link *lnk)
 	smc_ib_destroy_queue_pair(lnk);
 	smc_ib_dealloc_protection_domain(lnk);
 	smc_wr_free_link_mem(lnk);
+	if (!atomic_dec_return(&lnk->smcibdev->lnk_cnt))
+		wake_up(&lnk->smcibdev->lnks_deleted);
 }
 
 static void smcr_buf_free(struct smc_link_group *lgr, bool is_rmb,
@@ -492,6 +500,8 @@ static void smc_lgr_free(struct smc_link_group *lgr)
 	} else {
 		smc_link_clear(&lgr->lnk[SMC_SINGLE_LINK]);
 		put_device(&lgr->lnk[SMC_SINGLE_LINK].smcibdev->ibdev->dev);
+		if (!atomic_dec_return(&lgr_cnt))
+			wake_up(&lgrs_deleted);
 	}
 	kfree(lgr);
 }
@@ -729,6 +739,15 @@ void smc_smcr_terminate_all(struct smc_ib_device *smcibdev)
 		list_del_init(&lgr->list);
 		__smc_lgr_terminate(lgr, false);
 	}
+
+	if (smcibdev) {
+		if (atomic_read(&smcibdev->lnk_cnt))
+			wait_event(smcibdev->lnks_deleted,
+				   !atomic_read(&smcibdev->lnk_cnt));
+	} else {
+		if (atomic_read(&lgr_cnt))
+			wait_event(lgrs_deleted, !atomic_read(&lgr_cnt));
+	}
 }
 
 /* Determine vlan of internal TCP socket.
@@ -1263,6 +1282,12 @@ static void smc_lgrs_shutdown(void)
 	spin_unlock(&smcd_dev_list.lock);
 }
 
+int __init smc_core_init(void)
+{
+	atomic_set(&lgr_cnt, 0);
+	return 0;
+}
+
 /* Called (from smc_exit) when module is removed */
 void smc_core_exit(void)
 {

net/smc/smc_core.h

@@ -318,6 +318,7 @@ void smc_conn_free(struct smc_connection *conn);
 int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini);
 void smcd_conn_free(struct smc_connection *conn);
 void smc_lgr_schedule_free_work_fast(struct smc_link_group *lgr);
+int smc_core_init(void);
 void smc_core_exit(void);
 
 static inline struct smc_link_group *smc_get_lgr(struct smc_link *link)

net/smc/smc_ib.c

@@ -15,6 +15,7 @@
 #include <linux/random.h>
 #include <linux/workqueue.h>
 #include <linux/scatterlist.h>
+#include <linux/wait.h>
 #include <rdma/ib_verbs.h>
 #include <rdma/ib_cache.h>
 
@@ -543,7 +544,8 @@ static void smc_ib_add_dev(struct ib_device *ibdev)
 
 	smcibdev->ibdev = ibdev;
 	INIT_WORK(&smcibdev->port_event_work, smc_ib_port_event_work);
-
+	atomic_set(&smcibdev->lnk_cnt, 0);
+	init_waitqueue_head(&smcibdev->lnks_deleted);
 	spin_lock(&smc_ib_devices.lock);
 	list_add_tail(&smcibdev->list, &smc_ib_devices.list);
 	spin_unlock(&smc_ib_devices.lock);

net/smc/smc_ib.h

@@ -14,6 +14,7 @@
 
 #include <linux/interrupt.h>
 #include <linux/if_ether.h>
+#include <linux/wait.h>
 #include <rdma/ib_verbs.h>
 #include <net/smc.h>
 
@@ -48,6 +49,8 @@ struct smc_ib_device {				/* ib-device infos for smc */
 	struct work_struct	port_event_work;
 	unsigned long		port_event_mask;
 	DECLARE_BITMAP(ports_going_away, SMC_MAX_PORTS);
+	atomic_t		lnk_cnt;	/* number of links on ibdev */
+	wait_queue_head_t	lnks_deleted;	/* wait 4 removal of all links*/
 };
 
 struct smc_buf_desc;