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>

1 files changed, 25 insertions, 0 deletions

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 97e9d21c4d1e..cf34b9d96595 100644
--- a/net/smc/smc_core.c
+++ b/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)
 {