Re: [dpdk-dev] [PATCH] virtio: fix PCI config err handling

[Yuanhan Liu <yliu@fridaylinux.org>]

On Mon, Jun 05, 2017 at 04:44:33PM +0100, Brian Russell wrote:
> In virtio_read_caps, rte_pci_read_config returns the number of bytes
> read from PCI config or <0 on error.
> If less than the expected number of bytes are read then log the
> failure and return rather than carrying on with garbage.
> 
> Signed-off-by: Brian Russell <brussell@brocade.com>
> ---
>  drivers/net/virtio/virtio_pci.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
> index b7b3d61..90c098e 100644
> --- a/drivers/net/virtio/virtio_pci.c
> +++ b/drivers/net/virtio/virtio_pci.c
> @@ -592,16 +592,18 @@ virtio_read_caps(struct rte_pci_device *dev, struct virtio_hw *hw)
>  	}
>  
>  	ret = rte_pci_read_config(dev, &pos, 1, PCI_CAPABILITY_LIST);
> -	if (ret < 0) {
> -		PMD_INIT_LOG(DEBUG, "failed to read pci capability list");
> +	if (ret != 1) {
> +		PMD_INIT_LOG(DEBUG,
> +			     "failed to read pci capability list, ret %d", ret);
>  		return -1;
>  	}

There are two things worth mentioning:

- rte_pci.h states nothing about the return value

- The BSD implementation actually returns 0 on success, while the Linux
  implementation indeed returns the bytes read.

	--yliu