net/mlx4_core: Cleanup FMR unmapping flow

Remove redundant and not essential operations in fmr unmap/free.
According to device spec, in FMR unmap it is sufficient to set
ownership bit to SW. This allows remapping afterwards.

Fixes: 8ad11fb6b073 ("IB/mlx4: Implement FMRs")
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx4/mr.c b/drivers/net/ethernet/mellanox/mlx4/mr.c
index c7c0764991c981180b96f5ac8028a168648d03b7..2e84f10f59ba9ca0a69d980b87368f7310e5bb13 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/mr.c
+++ b/drivers/net/ethernet/mellanox/mlx4/mr.c
@@ -1103,30 +1103,16 @@ EXPORT_SYMBOL_GPL(mlx4_fmr_enable);
 void mlx4_fmr_unmap(struct mlx4_dev *dev, struct mlx4_fmr *fmr,
                    u32 *lkey, u32 *rkey)
 {
-       struct mlx4_cmd_mailbox *mailbox;
-       int err;
-
        if (!fmr->maps)
                return;
 
-       fmr->maps = 0;
+       /* To unmap: it is sufficient to take back ownership from HW */
+       *(u8 *)fmr->mpt = MLX4_MPT_STATUS_SW;
 
-       mailbox = mlx4_alloc_cmd_mailbox(dev);
-       if (IS_ERR(mailbox)) {
-               err = PTR_ERR(mailbox);
-               pr_warn("mlx4_ib: mlx4_alloc_cmd_mailbox failed (%d)\n", err);
-               return;
-       }
+       /* Make sure MPT status is visible */
+       wmb();
 
-       err = mlx4_HW2SW_MPT(dev, NULL,
-                            key_to_hw_index(fmr->mr.key) &
-                            (dev->caps.num_mpts - 1));
-       mlx4_free_cmd_mailbox(dev, mailbox);
-       if (err) {
-               pr_warn("mlx4_ib: mlx4_HW2SW_MPT failed (%d)\n", err);
-               return;
-       }
-       fmr->mr.enabled = MLX4_MPT_EN_SW;
+       fmr->maps = 0;
 }
 EXPORT_SYMBOL_GPL(mlx4_fmr_unmap);
 
@@ -1136,6 +1122,22 @@ int mlx4_fmr_free(struct mlx4_dev *dev, struct mlx4_fmr *fmr)
 
        if (fmr->maps)
                return -EBUSY;
+       if (fmr->mr.enabled == MLX4_MPT_EN_HW) {
+               /* In case of FMR was enabled and unmapped
+                * make sure to give ownership of MPT back to HW
+                * so HW2SW_MPT command will success.
+                */
+               *(u8 *)fmr->mpt = MLX4_MPT_STATUS_SW;
+               /* Make sure MPT status is visible before changing MPT fields */
+               wmb();
+               fmr->mpt->length = 0;
+               fmr->mpt->start  = 0;
+               /* Make sure MPT data is visible after changing MPT status */
+               wmb();
+               *(u8 *)fmr->mpt = MLX4_MPT_STATUS_HW;
+               /* make sure MPT status is visible */
+               wmb();
+       }
 
        ret = mlx4_mr_free(dev, &fmr->mr);
        if (ret)