[PATCH] virtio: fix PCI config err handling

[PATCH] virtio: fix PCI config err handling

[Brian Russell]

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;
 	}
 
 	while (pos) {
 		ret = rte_pci_read_config(dev, &cap, sizeof(cap), pos);
-		if (ret < 0) {
-			PMD_INIT_LOG(ERR,
-				"failed to read pci cap at pos: %x", pos);
+		if (ret != sizeof(cap)) {
+			PMD_INIT_LOG(DEBUG,
+				     "failed to read pci cap at pos: %x ret %d",
+				     pos, ret);
 			break;
 		}
 
-- 
2.1.4

Re: [PATCH] virtio: fix PCI config err handling

[Yuanhan Liu]

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