Re: [PATCH v5 18/26] nvme: use preallocated qsg/iov in nvme_dma_prp

From: Maxim Levitsky <mlevitsk@redhat.com>
To: Klaus Jensen <k.jensen@samsung.com>, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	Beata Michalska <beata.michalska@linaro.org>,
	qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>,
	Keith Busch <kbusch@kernel.org>, Klaus Jensen <its@irrelevant.dk>,
	Javier Gonzalez <javier.gonz@samsung.com>
Subject: Re: [PATCH v5 18/26] nvme: use preallocated qsg/iov in nvme_dma_prp
Date: Wed, 12 Feb 2020 13:49:48 +0200	[thread overview]
Message-ID: <ba2bed5cd14c8eb2247e82c8da9ed3b6cd5ce58c.camel@redhat.com> (raw)
In-Reply-To: <20200204095208.269131-19-k.jensen@samsung.com>

On Tue, 2020-02-04 at 10:52 +0100, Klaus Jensen wrote:
> Since clean up of the request qsg/iov has been moved to the common
> nvme_enqueue_req_completion function, there is no need to use a
> stack allocated qsg/iov in nvme_dma_prp.
> 
> Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> ---
>  hw/block/nvme.c | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index e97da35c4ca1..f8c81b9e2202 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -298,23 +298,21 @@ unmap:
>  static uint16_t nvme_dma_prp(NvmeCtrl *n, uint8_t *ptr, uint32_t len,
>      uint64_t prp1, uint64_t prp2, DMADirection dir, NvmeRequest *req)
>  {
> -    QEMUSGList qsg;
> -    QEMUIOVector iov;
>      uint16_t status = NVME_SUCCESS;
>      size_t bytes;
>  
> -    status = nvme_map_prp(n, &qsg, &iov, prp1, prp2, len, req);
> +    status = nvme_map_prp(n, &req->qsg, &req->iov, prp1, prp2, len, req);
>      if (status) {
>          return status;
>      }
>  
> -    if (qsg.nsg > 0) {
> +    if (req->qsg.nsg > 0) {
>          uint64_t residual;
>  
>          if (dir == DMA_DIRECTION_TO_DEVICE) {
> -            residual = dma_buf_write(ptr, len, &qsg);
> +            residual = dma_buf_write(ptr, len, &req->qsg);
>          } else {
> -            residual = dma_buf_read(ptr, len, &qsg);
> +            residual = dma_buf_read(ptr, len, &req->qsg);
>          }
>  
>          if (unlikely(residual)) {
> @@ -322,15 +320,13 @@ static uint16_t nvme_dma_prp(NvmeCtrl *n, uint8_t *ptr, uint32_t len,
>              status = NVME_INVALID_FIELD | NVME_DNR;
>          }
>  
> -        qemu_sglist_destroy(&qsg);
> -
>          return status;
>      }
>  
>      if (dir == DMA_DIRECTION_TO_DEVICE) {
> -        bytes = qemu_iovec_to_buf(&iov, 0, ptr, len);
> +        bytes = qemu_iovec_to_buf(&req->iov, 0, ptr, len);
>      } else {
> -        bytes = qemu_iovec_from_buf(&iov, 0, ptr, len);
> +        bytes = qemu_iovec_from_buf(&req->iov, 0, ptr, len);
>      }
>  
>      if (unlikely(bytes != len)) {
> @@ -338,8 +334,6 @@ static uint16_t nvme_dma_prp(NvmeCtrl *n, uint8_t *ptr, uint32_t len,
>          status = NVME_INVALID_FIELD | NVME_DNR;
>      }
>  
> -    qemu_iovec_destroy(&iov);
> -
>      return status;
>  }
>  


Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky