[PATCH 04/16] drivers, net, mlx4: convert mlx4_qp.refcount from atomic_t to refcount_t

[Elena Reshetova]

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 drivers/net/ethernet/mellanox/mlx4/qp.c | 8 ++++----
 include/linux/mlx4/device.h             | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/qp.c 
b/drivers/net/ethernet/mellanox/mlx4/qp.c
index 2d6abd4..6017316 100644
--- a/drivers/net/ethernet/mellanox/mlx4/qp.c
+++ b/drivers/net/ethernet/mellanox/mlx4/qp.c
@@ -55,7 +55,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int 
event_type)
 
        qp = __mlx4_qp_lookup(dev, qpn);
        if (qp)
-               atomic_inc(&qp->refcount);
+               refcount_inc(&qp->refcount);
 
        spin_unlock(&qp_table->lock);
 
@@ -66,7 +66,7 @@ void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int 
event_type)
 
        qp->event(qp, event_type);
 
-       if (atomic_dec_and_test(&qp->refcount))
+       if (refcount_dec_and_test(&qp->refcount))
                complete(&qp->free);
 }
 
@@ -406,7 +406,7 @@ int mlx4_qp_alloc(struct mlx4_dev *dev, int qpn, struct 
mlx4_qp *qp, gfp_t gfp)
        if (err)
                goto err_icm;
 
-       atomic_set(&qp->refcount, 1);
+       refcount_set(&qp->refcount, 1);
        init_completion(&qp->free);
 
        return 0;
@@ -500,7 +500,7 @@ EXPORT_SYMBOL_GPL(mlx4_qp_remove);
 
 void mlx4_qp_free(struct mlx4_dev *dev, struct mlx4_qp *qp)
 {
-       if (atomic_dec_and_test(&qp->refcount))
+       if (refcount_dec_and_test(&qp->refcount))
                complete(&qp->free);
        wait_for_completion(&qp->free);
 
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index 5fea001..756ca22 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -754,7 +754,7 @@ struct mlx4_qp {
 
        int                     qpn;
 
-       atomic_t                refcount;
+       refcount_t              refcount;
        struct completion       free;
 };
 
-- 
2.7.4