[PATCH v5 9/9] IB/mlx5: Replace semaphore umr_common:sem with wait_event

[Binoy Jayan]

Remove semaphore umr_common:sem used to limit concurrent access to umr qp
and introduce an atomic value 'users' to keep track of the same. Use a
wait_event to block when the limit is reached.

Signed-off-by: Binoy Jayan <binoy.ja...@linaro.org>
---
 drivers/infiniband/hw/mlx5/main.c    | 6 +-----
 drivers/infiniband/hw/mlx5/mlx5_ib.h | 7 ++++++-
 drivers/infiniband/hw/mlx5/mr.c      | 6 ++++--
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c 
b/drivers/infiniband/hw/mlx5/main.c
index 63036c7..9de716c 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -2437,10 +2437,6 @@ static void destroy_umrc_res(struct mlx5_ib_dev *dev)
        ib_dealloc_pd(dev->umrc.pd);
 }
 
-enum {
-       MAX_UMR_WR = 128,
-};
-
 static int create_umr_res(struct mlx5_ib_dev *dev)
 {
        struct ib_qp_init_attr *init_attr = NULL;
@@ -2520,7 +2516,7 @@ static int create_umr_res(struct mlx5_ib_dev *dev)
        dev->umrc.cq = cq;
        dev->umrc.pd = pd;
 
-       sema_init(&dev->umrc.sem, MAX_UMR_WR);
+       init_waitqueue_head(&dev->umrc.wq);
        ret = mlx5_mr_cache_init(dev);
        if (ret) {
                mlx5_ib_warn(dev, "mr cache init failed %d\n", ret);
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h 
b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index dcdcd19..de31b5f 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -533,7 +533,12 @@ struct umr_common {
        struct ib_qp    *qp;
        /* control access to UMR QP
         */
-       struct semaphore        sem;
+       wait_queue_head_t       wq;
+       atomic_t                users;
+};
+
+enum {
+       MAX_UMR_WR = 128,
 };
 
 enum {
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 1593856..dfaf6f6 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -867,7 +867,8 @@ static inline int mlx5_ib_post_send_wait(struct mlx5_ib_dev 
*dev,
        mlx5_ib_init_umr_context(&umr_context);
        umrwr->wr.wr_cqe = &umr_context.cqe;
 
-       down(&umrc->sem);
+       /* limit number of concurrent ib_post_send() on qp */
+       wait_event(umrc->wq, atomic_add_unless(&umrc->users, 1, MAX_UMR_WR));
        err = ib_post_send(umrc->qp, &umrwr->wr, &bad);
        if (err) {
                mlx5_ib_warn(dev, "UMR post send failed, err %d\n", err);
@@ -879,7 +880,8 @@ static inline int mlx5_ib_post_send_wait(struct mlx5_ib_dev 
*dev,
                        err = -EFAULT;
                }
        }
-       up(&umrc->sem);
+       atomic_dec(&umrc->users);
+       wake_up(&umrc->wq);
        return err;
 }
 
-- 
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