diff options
Diffstat (limited to 'drivers/infiniband/hw/mlx5/odp.c')
| -rw-r--r-- | drivers/infiniband/hw/mlx5/odp.c | 34 |
1 files changed, 32 insertions, 2 deletions
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c index 2e9b43061797..3401c06b7e54 100644 --- a/drivers/infiniband/hw/mlx5/odp.c +++ b/drivers/infiniband/hw/mlx5/odp.c @@ -178,6 +178,29 @@ void mlx5_odp_populate_klm(struct mlx5_klm *pklm, size_t offset, return; } + /* + * The locking here is pretty subtle. Ideally the implicit children + * list would be protected by the umem_mutex, however that is not + * possible. Instead this uses a weaker update-then-lock pattern: + * + * srcu_read_lock() + * <change children list> + * mutex_lock(umem_mutex) + * mlx5_ib_update_xlt() + * mutex_unlock(umem_mutex) + * destroy lkey + * + * ie any change the children list must be followed by the locked + * update_xlt before destroying. + * + * The umem_mutex provides the acquire/release semantic needed to make + * the children list visible to a racing thread. While SRCU is not + * technically required, using it gives consistent use of the SRCU + * locking around the children list. + */ + lockdep_assert_held(&to_ib_umem_odp(mr->umem)->umem_mutex); + lockdep_assert_held(&mr->dev->mr_srcu); + odp = odp_lookup(offset * MLX5_IMR_MTT_SIZE, nentries * MLX5_IMR_MTT_SIZE, mr); @@ -202,15 +225,22 @@ static void mr_leaf_free_action(struct work_struct *work) struct ib_umem_odp *odp = container_of(work, struct ib_umem_odp, work); int idx = ib_umem_start(odp) >> MLX5_IMR_MTT_SHIFT; struct mlx5_ib_mr *mr = odp->private, *imr = mr->parent; + struct ib_umem_odp *odp_imr = to_ib_umem_odp(imr->umem); + int srcu_key; mr->parent = NULL; synchronize_srcu(&mr->dev->mr_srcu); - ib_umem_odp_release(odp); - if (imr->live) + if (imr->live) { + srcu_key = srcu_read_lock(&mr->dev->mr_srcu); + mutex_lock(&odp_imr->umem_mutex); mlx5_ib_update_xlt(imr, idx, 1, 0, MLX5_IB_UPD_XLT_INDIRECT | MLX5_IB_UPD_XLT_ATOMIC); + mutex_unlock(&odp_imr->umem_mutex); + srcu_read_unlock(&mr->dev->mr_srcu, srcu_key); + } + ib_umem_odp_release(odp); mlx5_mr_cache_free(mr->dev, mr); if (atomic_dec_and_test(&imr->num_leaf_free)) |