[dpdk-dev,4/4] net/mlx5: remove MR refcnt

  MRs are registered to priv at device start or on the fly, destroyied
when device stop.
No mR registration to perticular TXQ, MR references cache in TXQ just
part of device MR list, no reason to keep MR refcnt.

Signed-off-by: Xueming Li <xuemingl@mellanox.com>
---
 drivers/net/mlx5/mlx5.h      |  1 -
 drivers/net/mlx5/mlx5_mr.c   | 51 +++++---------------------------------------
 drivers/net/mlx5/mlx5_rxq.c  |  1 -
 drivers/net/mlx5/mlx5_rxtx.h |  2 --
 drivers/net/mlx5/mlx5_txq.c  | 18 ----------------
 5 files changed, 5 insertions(+), 68 deletions(-)
  

Hi Xueming,

On Mon, Jan 15, 2018 at 02:54:20PM +0800, Xueming Li wrote:
> MRs are registered to priv at device start or on the fly, destroyied
> when device stop.
> No mR registration to perticular TXQ, MR references cache in TXQ just
> part of device MR list, no reason to keep MR refcnt.
> 
> Signed-off-by: Xueming Li <xuemingl@mellanox.com>
> ---
>  drivers/net/mlx5/mlx5.h      |  1 -
>  drivers/net/mlx5/mlx5_mr.c   | 51 +++++---------------------------------------
>  drivers/net/mlx5/mlx5_rxq.c  |  1 -
>  drivers/net/mlx5/mlx5_rxtx.h |  2 --
>  drivers/net/mlx5/mlx5_txq.c  | 18 ----------------
>  5 files changed, 5 insertions(+), 68 deletions(-)
> 
> diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
> index a6cd1474c..df6a70d96 100644
> --- a/drivers/net/mlx5/mlx5.h
> +++ b/drivers/net/mlx5/mlx5.h
> @@ -318,7 +318,6 @@ int priv_socket_connect(struct priv *priv);
>  
>  struct mlx5_mr *priv_mr_new(struct priv *priv, struct rte_mempool *mp,
>  			    uintptr_t addr);
> -struct mlx5_mr *priv_mr_get(struct priv *, struct rte_mempool *);
>  int priv_mr_release(struct priv *, struct mlx5_mr *);
>  int priv_mr_verify(struct priv *);
>  struct mlx5_mr *priv_mr_lookup(struct priv *priv, uintptr_t addr);
> diff --git a/drivers/net/mlx5/mlx5_mr.c b/drivers/net/mlx5/mlx5_mr.c
> index 8d8fabea1..bd1be5606 100644
> --- a/drivers/net/mlx5/mlx5_mr.c
> +++ b/drivers/net/mlx5/mlx5_mr.c
> @@ -88,15 +88,11 @@ mlx5_mempool_register_cb(struct rte_mempool *mp, void *opaque,
>  		cb->error = -1;
>  		return;
>  	}
> -	mr->mp = mp;
>  	DEBUG("mempool %p:%u area start=%p size=%zu lkey=0x%08x",
>  	      (void *)mp, mem_idx, memhdr->addr, memhdr->len, mr->mr->lkey);
>  	mr->lkey = rte_cpu_to_be_32(mr->mr->lkey);
>  	mr->start = (uintptr_t)memhdr->addr;
>  	mr->end = (uintptr_t)mr->mr->addr + mr->mr->length;
> -	rte_atomic32_inc(&mr->refcnt);
> -	DEBUG("%p: new Memory Region %p refcnt: %d", (void *)priv,
> -	      (void *)mr, rte_atomic32_read(&mr->refcnt));

Please keep the debug message.

>  	LIST_INSERT_HEAD(&priv->mr, mr, next);
>  	cb->mr = mr;
>  }
> @@ -121,11 +117,8 @@ mlx5_mp2mr(struct priv *priv, struct rte_mempool *mp, uintptr_t addr)
>  
>  	priv_lock(priv);
>  	mr = priv_mr_lookup(priv, addr);
> -	if (!mr) {
> +	if (!mr)
>  		mr = priv_mr_new(priv, mp, addr);
> -		if (mr)
> -			rte_atomic32_inc(&mr->refcnt);
> -	}
>  	priv_unlock(priv);
>  	return mr;
>  }
> @@ -217,35 +210,6 @@ priv_mr_new(struct priv *priv, struct rte_mempool *mp, uintptr_t addr)
>  }
>  
>  /**
> - * Search the memory region object in the memory region list.
> - *
> - * @param  priv
> - *   Pointer to private structure.
> - * @param mp
> - *   Pointer to the memory pool to register.
> - * @return
> - *   The memory region on success.
> - */
> -struct mlx5_mr*
> -priv_mr_get(struct priv *priv, struct rte_mempool *mp)
> -{
> -	struct mlx5_mr *mr;
> -
> -	assert(mp);
> -	if (LIST_EMPTY(&priv->mr))
> -		return NULL;
> -	LIST_FOREACH(mr, &priv->mr, next) {
> -		if (mr->mp == mp) {
> -			rte_atomic32_inc(&mr->refcnt);
> -			DEBUG("Memory Region %p refcnt: %d",
> -			      (void *)mr, rte_atomic32_read(&mr->refcnt));
> -			return mr;
> -		}
> -	}
> -	return NULL;
> -}
> -
> -/**
>   * Release the memory region object.
>   *
>   * @param  mr
> @@ -259,15 +223,10 @@ priv_mr_release(struct priv *priv, struct mlx5_mr *mr)
>  {
>  	(void)priv;
>  	assert(mr);
> -	DEBUG("Memory Region %p refcnt: %d",
> -	      (void *)mr, rte_atomic32_read(&mr->refcnt));
> -	if (rte_atomic32_dec_and_test(&mr->refcnt)) {
> -		claim_zero(ibv_dereg_mr(mr->mr));
> -		LIST_REMOVE(mr, next);
> -		rte_free(mr);
> -		return 0;
> -	}
> -	return EBUSY;
> +	claim_zero(ibv_dereg_mr(mr->mr));
> +	LIST_REMOVE(mr, next);
> +	rte_free(mr);
> +	return 0;
>  }
>  
>  /**
> diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
> index a581a2d61..461b4ff91 100644
> --- a/drivers/net/mlx5/mlx5_rxq.c
> +++ b/drivers/net/mlx5/mlx5_rxq.c
> @@ -852,7 +852,6 @@ mlx5_priv_rxq_ibv_get(struct priv *priv, uint16_t idx)
>  		return NULL;
>  	rxq_ctrl = container_of(rxq_data, struct mlx5_rxq_ctrl, rxq);
>  	if (rxq_ctrl->ibv) {
> -		priv_mr_get(priv, rxq_data->mp);
>  		rte_atomic32_inc(&rxq_ctrl->ibv->refcnt);
>  		DEBUG("%p: Verbs Rx queue %p: refcnt %d", (void *)priv,
>  		      (void *)rxq_ctrl->ibv,
> diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
> index 6589a662e..0b8332cc0 100644
> --- a/drivers/net/mlx5/mlx5_rxtx.h
> +++ b/drivers/net/mlx5/mlx5_rxtx.h
> @@ -85,12 +85,10 @@ struct priv;
>  /* Memory region queue object. */
>  struct mlx5_mr {
>  	LIST_ENTRY(mlx5_mr) next; /**< Pointer to the next element. */
> -	rte_atomic32_t refcnt; /*<< Reference counter. */
>  	uint32_t lkey; /*<< rte_cpu_to_be_32(mr->lkey) */
>  	uintptr_t start; /* Start address of MR */
>  	uintptr_t end; /* End address of MR */
>  	struct ibv_mr *mr; /*<< Memory Region. */
> -	struct rte_mempool *mp; /*<< Memory Pool. */
>  };
>  
>  /* Compressed CQE context. */
> diff --git a/drivers/net/mlx5/mlx5_txq.c b/drivers/net/mlx5/mlx5_txq.c
> index 26db15a4f..3c337a4ac 100644
> --- a/drivers/net/mlx5/mlx5_txq.c
> +++ b/drivers/net/mlx5/mlx5_txq.c
> @@ -801,18 +801,7 @@ mlx5_priv_txq_get(struct priv *priv, uint16_t idx)
>  	if ((*priv->txqs)[idx]) {
>  		ctrl = container_of((*priv->txqs)[idx], struct mlx5_txq_ctrl,
>  				    txq);
> -		unsigned int i;
> -
>  		mlx5_priv_txq_ibv_get(priv, idx);
> -		for (i = 0; i != MLX5_PMD_TX_MP_CACHE; ++i) {
> -			struct mlx5_mr *mr = NULL;
> -
> -			(void)mr;
> -			if (ctrl->txq.mp2mr[i]) {
> -				mr = priv_mr_get(priv, ctrl->txq.mp2mr[i]->mp);
> -				assert(mr);
> -			}
> -		}
>  		rte_atomic32_inc(&ctrl->refcnt);
>  		DEBUG("%p: Tx queue %p: refcnt %d", (void *)priv,
>  		      (void *)ctrl, rte_atomic32_read(&ctrl->refcnt));
> @@ -834,7 +823,6 @@ mlx5_priv_txq_get(struct priv *priv, uint16_t idx)
>  int
>  mlx5_priv_txq_release(struct priv *priv, uint16_t idx)
>  {
> -	unsigned int i;
>  	struct mlx5_txq_ctrl *txq;
>  
>  	if (!(*priv->txqs)[idx])
> @@ -849,12 +837,6 @@ mlx5_priv_txq_release(struct priv *priv, uint16_t idx)
>  		if (!ret)
>  			txq->ibv = NULL;
>  	}
> -	for (i = 0; i != MLX5_PMD_TX_MP_CACHE; ++i) {
> -		if (txq->txq.mp2mr[i]) {
> -			priv_mr_release(priv, txq->txq.mp2mr[i]);
> -			txq->txq.mp2mr[i] = NULL;
> -		}
> -	}

Nullifying the case when the queue is release should remain.  It is
better to detect an access to a null pointer than to a freed memory
space.

>  	if (rte_atomic32_dec_and_test(&txq->refcnt)) {
>  		txq_free_elts(txq);
>  		LIST_REMOVE(txq, next);
> -- 
> 2.13.3
> 

Thanks,