linux-kernel - [PATCH rdma-next 2/3] RDMA/iwpm: Remove not-needed reference counting

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Date:   Fri, 23 Jul 2021 17:08:56 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>
Cc:     Leon Romanovsky <leonro@...dia.com>,
        Faisal Latif <faisal.latif@...el.com>,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        Mustafa Ismail <mustafa.ismail@...el.com>,
        Steve Wise <larrystevenwise@...il.com>,
        "Tatyana E. Nikolova" <tatyana.e.nikolova@...el.com>
Subject: [PATCH rdma-next 2/3] RDMA/iwpm: Remove not-needed reference counting

From: Leon Romanovsky <leonro@...dia.com>

iwpm_init() and iwpm_exit() are called only once during iw_cm module
load. This makes whole reference count implementation not needed at all.

Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
 drivers/infiniband/core/iwpm_util.c | 62 ++++++++---------------------
 drivers/infiniband/core/iwpm_util.h |  1 -
 2 files changed, 16 insertions(+), 47 deletions(-)

diff --git a/drivers/infiniband/core/iwpm_util.c b/drivers/infiniband/core/iwpm_util.c
index 3f8c019c7260..45e9aa503a44 100644
--- a/drivers/infiniband/core/iwpm_util.c
+++ b/drivers/infiniband/core/iwpm_util.c
@@ -48,7 +48,6 @@ static DEFINE_SPINLOCK(iwpm_mapinfo_lock);
 static struct hlist_head *iwpm_reminfo_bucket;
 static DEFINE_SPINLOCK(iwpm_reminfo_lock);
 
-static DEFINE_MUTEX(iwpm_admin_lock);
 static struct iwpm_admin_data iwpm_admin;
 
 /**
@@ -59,39 +58,22 @@ static struct iwpm_admin_data iwpm_admin;
  */
 int iwpm_init(u8 nl_client)
 {
-	int ret = 0;
-	mutex_lock(&iwpm_admin_lock);
-	if (!refcount_read(&iwpm_admin.refcount)) {
-		iwpm_hash_bucket = kcalloc(IWPM_MAPINFO_HASH_SIZE,
-					   sizeof(struct hlist_head),
-					   GFP_KERNEL);
-		if (!iwpm_hash_bucket) {
-			ret = -ENOMEM;
-			goto init_exit;
-		}
-		iwpm_reminfo_bucket = kcalloc(IWPM_REMINFO_HASH_SIZE,
-					      sizeof(struct hlist_head),
-					      GFP_KERNEL);
-		if (!iwpm_reminfo_bucket) {
-			kfree(iwpm_hash_bucket);
-			ret = -ENOMEM;
-			goto init_exit;
-		}
+	iwpm_hash_bucket = kcalloc(IWPM_MAPINFO_HASH_SIZE,
+				   sizeof(struct hlist_head), GFP_KERNEL);
+	if (!iwpm_hash_bucket)
+		return -ENOMEM;
 
-		refcount_set(&iwpm_admin.refcount, 1);
-	} else {
-		refcount_inc(&iwpm_admin.refcount);
+	iwpm_reminfo_bucket = kcalloc(IWPM_REMINFO_HASH_SIZE,
+				      sizeof(struct hlist_head), GFP_KERNEL);
+	if (!iwpm_reminfo_bucket) {
+		kfree(iwpm_hash_bucket);
+		return -ENOMEM;
 	}
 
-init_exit:
-	mutex_unlock(&iwpm_admin_lock);
-	if (!ret) {
-		iwpm_set_valid(nl_client, 1);
-		iwpm_set_registration(nl_client, IWPM_REG_UNDEF);
-		pr_debug("%s: Mapinfo and reminfo tables are created\n",
-				__func__);
-	}
-	return ret;
+	iwpm_set_valid(nl_client, 1);
+	iwpm_set_registration(nl_client, IWPM_REG_UNDEF);
+	pr_debug("%s: Mapinfo and reminfo tables are created\n", __func__);
+	return 0;
 }
 
 static void free_hash_bucket(void);
@@ -105,21 +87,9 @@ static void free_reminfo_bucket(void);
  */
 int iwpm_exit(u8 nl_client)
 {
-
-	if (!iwpm_valid_client(nl_client))
-		return -EINVAL;
-	mutex_lock(&iwpm_admin_lock);
-	if (!refcount_read(&iwpm_admin.refcount)) {
-		mutex_unlock(&iwpm_admin_lock);
-		pr_err("%s Incorrect usage - negative refcount\n", __func__);
-		return -EINVAL;
-	}
-	if (refcount_dec_and_test(&iwpm_admin.refcount)) {
-		free_hash_bucket();
-		free_reminfo_bucket();
-		pr_debug("%s: Resources are destroyed\n", __func__);
-	}
-	mutex_unlock(&iwpm_admin_lock);
+	free_hash_bucket();
+	free_reminfo_bucket();
+	pr_debug("%s: Resources are destroyed\n", __func__);
 	iwpm_set_valid(nl_client, 0);
 	iwpm_set_registration(nl_client, IWPM_REG_UNDEF);
 	return 0;
diff --git a/drivers/infiniband/core/iwpm_util.h b/drivers/infiniband/core/iwpm_util.h
index e201835de733..e2eacc017078 100644
--- a/drivers/infiniband/core/iwpm_util.h
+++ b/drivers/infiniband/core/iwpm_util.h
@@ -90,7 +90,6 @@ struct iwpm_remote_info {
 };
 
 struct iwpm_admin_data {
-	refcount_t refcount;
 	atomic_t nlmsg_seq;
 	int      client_list[RDMA_NL_NUM_CLIENTS];
 	u32      reg_list[RDMA_NL_NUM_CLIENTS];
-- 
2.31.1