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From:   Chuhong Yuan <hslester96@gmail.com>
Cc:     Leon Romanovsky <leon@kernel.org>,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Saeed Mahameed <saeedm@mellanox.com>,
        "David S . Miller" <davem@davemloft.net>,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, Chuhong Yuan <hslester96@gmail.com>
Subject: [PATCH v3] mlx5: Use refcount_t for refcount
Date:   Tue,  6 Aug 2019 09:59:50 +0800
Message-Id: <20190806015950.18167-1-hslester96@gmail.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Reference counters are preferred to use refcount_t instead of
atomic_t.
This is because the implementation of refcount_t can prevent
overflows and detect possible use-after-free.
So convert atomic_t ref counters to refcount_t.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
Changes in v3:
  - Merge v2 patches together.

 drivers/infiniband/hw/mlx5/srq_cmd.c         | 6 +++---
 drivers/net/ethernet/mellanox/mlx5/core/qp.c | 6 +++---
 include/linux/mlx5/driver.h                  | 3 ++-
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/srq_cmd.c b/drivers/infiniband/hw/mlx5/srq_cmd.c
index b0d0687c7a68..8fc3630a9d4c 100644
--- a/drivers/infiniband/hw/mlx5/srq_cmd.c
+++ b/drivers/infiniband/hw/mlx5/srq_cmd.c
@@ -86,7 +86,7 @@ struct mlx5_core_srq *mlx5_cmd_get_srq(struct mlx5_ib_dev *dev, u32 srqn)
 	xa_lock(&table->array);
 	srq = xa_load(&table->array, srqn);
 	if (srq)
-		atomic_inc(&srq->common.refcount);
+		refcount_inc(&srq->common.refcount);
 	xa_unlock(&table->array);
 
 	return srq;
@@ -592,7 +592,7 @@ int mlx5_cmd_create_srq(struct mlx5_ib_dev *dev, struct mlx5_core_srq *srq,
 	if (err)
 		return err;
 
-	atomic_set(&srq->common.refcount, 1);
+	refcount_set(&srq->common.refcount, 1);
 	init_completion(&srq->common.free);
 
 	err = xa_err(xa_store_irq(&table->array, srq->srqn, srq, GFP_KERNEL));
@@ -675,7 +675,7 @@ static int srq_event_notifier(struct notifier_block *nb,
 	xa_lock(&table->array);
 	srq = xa_load(&table->array, srqn);
 	if (srq)
-		atomic_inc(&srq->common.refcount);
+		refcount_inc(&srq->common.refcount);
 	xa_unlock(&table->array);
 
 	if (!srq)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/qp.c b/drivers/net/ethernet/mellanox/mlx5/core/qp.c
index b8ba74de9555..7b44d1e49604 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/qp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/qp.c
@@ -53,7 +53,7 @@ mlx5_get_rsc(struct mlx5_qp_table *table, u32 rsn)
 
 	common = radix_tree_lookup(&table->tree, rsn);
 	if (common)
-		atomic_inc(&common->refcount);
+		refcount_inc(&common->refcount);
 
 	spin_unlock_irqrestore(&table->lock, flags);
 
@@ -62,7 +62,7 @@ mlx5_get_rsc(struct mlx5_qp_table *table, u32 rsn)
 
 void mlx5_core_put_rsc(struct mlx5_core_rsc_common *common)
 {
-	if (atomic_dec_and_test(&common->refcount))
+	if (refcount_dec_and_test(&common->refcount))
 		complete(&common->free);
 }
 
@@ -209,7 +209,7 @@ static int create_resource_common(struct mlx5_core_dev *dev,
 	if (err)
 		return err;
 
-	atomic_set(&qp->common.refcount, 1);
+	refcount_set(&qp->common.refcount, 1);
 	init_completion(&qp->common.free);
 	qp->pid = current->pid;
 
diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
index 0e6da1840c7d..5b56f343ce87 100644
--- a/include/linux/mlx5/driver.h
+++ b/include/linux/mlx5/driver.h
@@ -47,6 +47,7 @@
 #include <linux/interrupt.h>
 #include <linux/idr.h>
 #include <linux/notifier.h>
+#include <linux/refcount.h>
 
 #include <linux/mlx5/device.h>
 #include <linux/mlx5/doorbell.h>
@@ -398,7 +399,7 @@ enum mlx5_res_type {
 
 struct mlx5_core_rsc_common {
 	enum mlx5_res_type	res;
-	atomic_t		refcount;
+	refcount_t		refcount;
 	struct completion	free;
 };
 
-- 
2.20.1