The virtnet_send_command_reply() function returns true on success or
false on failure.  The "ok" variable is true/false depending on whether
it succeeds or not.  It's up to the caller to translate the true/false
into -EINVAL on failure or zero for success.

The bug is that __virtnet_get_hw_stats() returns false for both
errors and success.  It's not a bug, but it is confusing that the caller
virtnet_get_hw_stats() uses an "ok" variable to store negative error
codes.

Fix the bug and clean things up so that it's clear that
__virtnet_get_hw_stats() returns zero on success or negative error codes
on failure.

Fixes: 941168f8b40e ("virtio_net: support device stats")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/net/virtio_net.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 218a446c4c27..4fc0fcdad259 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -4016,7 +4016,7 @@ static int __virtnet_get_hw_stats(struct virtnet_info *vi,
 					&sgs_out, &sgs_in);
 
 	if (!ok)
-		return ok;
+		return -EINVAL;
 
 	for (p = reply; p - reply < res_size; p += le16_to_cpu(hdr->size)) {
 		hdr = p;
@@ -4053,7 +4053,7 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
 	struct virtio_net_ctrl_queue_stats *req;
 	bool enable_cvq;
 	void *reply;
-	int ok;
+	int err;
 
 	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_DEVICE_STATS))
 		return 0;
@@ -4100,12 +4100,12 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
 	if (enable_cvq)
 		virtnet_make_stat_req(vi, ctx, req, vi->max_queue_pairs * 2, &j);
 
-	ok = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
+	err = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
 
 	kfree(req);
 	kfree(reply);
 
-	return ok;
+	return err;
 }
 
 static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)

On Fri, 10 May 2024 15:50:45 +0300, Dan Carpenter <dan.carpenter@linaro.org> wrote:
> The virtnet_send_command_reply() function returns true on success or
> false on failure.  The "ok" variable is true/false depending on whether
> it succeeds or not.  It's up to the caller to translate the true/false
> into -EINVAL on failure or zero for success.
>
> The bug is that __virtnet_get_hw_stats() returns false for both
> errors and success.  It's not a bug, but it is confusing that the caller
> virtnet_get_hw_stats() uses an "ok" variable to store negative error
> codes.
>
> Fix the bug and clean things up so that it's clear that
> __virtnet_get_hw_stats() returns zero on success or negative error codes
> on failure.
>
> Fixes: 941168f8b40e ("virtio_net: support device stats")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

That confused me too.

Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>

Thanks.


> ---
>  drivers/net/virtio_net.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 218a446c4c27..4fc0fcdad259 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -4016,7 +4016,7 @@ static int __virtnet_get_hw_stats(struct virtnet_info *vi,
>  					&sgs_out, &sgs_in);
>
>  	if (!ok)
> -		return ok;
> +		return -EINVAL;
>
>  	for (p = reply; p - reply < res_size; p += le16_to_cpu(hdr->size)) {
>  		hdr = p;
> @@ -4053,7 +4053,7 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
>  	struct virtio_net_ctrl_queue_stats *req;
>  	bool enable_cvq;
>  	void *reply;
> -	int ok;
> +	int err;
>
>  	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_DEVICE_STATS))
>  		return 0;
> @@ -4100,12 +4100,12 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
>  	if (enable_cvq)
>  		virtnet_make_stat_req(vi, ctx, req, vi->max_queue_pairs * 2, &j);
>
> -	ok = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
> +	err = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
>
>  	kfree(req);
>  	kfree(reply);
>
> -	return ok;
> +	return err;
>  }
>
>  static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)
>

On Fri, May 10, 2024 at 03:50:45PM +0300, Dan Carpenter wrote:
> The virtnet_send_command_reply() function returns true on success or
> false on failure.  The "ok" variable is true/false depending on whether
> it succeeds or not.  It's up to the caller to translate the true/false
> into -EINVAL on failure or zero for success.
> 
> The bug is that __virtnet_get_hw_stats() returns false for both
> errors and success.  It's not a bug, but it is confusing that the caller
> virtnet_get_hw_stats() uses an "ok" variable to store negative error
> codes.

The bug is ... It's not a bug ....

I think what you are trying to say is that the error isn't
really handled anyway, except for printing a warning,
so it's not a big deal.

Right?

I don't know why can't get_ethtool_stats fail - we should
probably fix that.


> Fix the bug and clean things up so that it's clear that
> __virtnet_get_hw_stats() returns zero on success or negative error codes
> on failure.
> 
> Fixes: 941168f8b40e ("virtio_net: support device stats")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
>  drivers/net/virtio_net.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 218a446c4c27..4fc0fcdad259 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -4016,7 +4016,7 @@ static int __virtnet_get_hw_stats(struct virtnet_info *vi,
>  					&sgs_out, &sgs_in);
>  
>  	if (!ok)
> -		return ok;
> +		return -EINVAL;
>  
>  	for (p = reply; p - reply < res_size; p += le16_to_cpu(hdr->size)) {
>  		hdr = p;
> @@ -4053,7 +4053,7 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
>  	struct virtio_net_ctrl_queue_stats *req;
>  	bool enable_cvq;
>  	void *reply;
> -	int ok;
> +	int err;
>  
>  	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_DEVICE_STATS))
>  		return 0;
> @@ -4100,12 +4100,12 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
>  	if (enable_cvq)
>  		virtnet_make_stat_req(vi, ctx, req, vi->max_queue_pairs * 2, &j);
>  
> -	ok = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
> +	err = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
>  
>  	kfree(req);
>  	kfree(reply);
>  
> -	return ok;
> +	return err;
>  }
>  
>  static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)

On Sun, May 12, 2024 at 12:01:55PM -0400, Michael S. Tsirkin wrote:
> On Fri, May 10, 2024 at 03:50:45PM +0300, Dan Carpenter wrote:
> > The virtnet_send_command_reply() function returns true on success or
> > false on failure.  The "ok" variable is true/false depending on whether
> > it succeeds or not.  It's up to the caller to translate the true/false
> > into -EINVAL on failure or zero for success.
> > 
> > The bug is that __virtnet_get_hw_stats() returns false for both
> > errors and success.  It's not a bug, but it is confusing that the caller
> > virtnet_get_hw_stats() uses an "ok" variable to store negative error
> > codes.
> 
> The bug is ... It's not a bug ....
> 
> I think what you are trying to say is that the error isn't
> really handled anyway, except for printing a warning,
> so it's not a big deal.
> 
> Right?
> 

No, I'm sorry, that was confusing.  The change to __virtnet_get_hw_stats()
is a bugfix but the change to virtnet_get_hw_stats() was not a bugfix.
I viewed this all as really one thing, because it's cleaning up the
error codes which happens to fix a bug.  It seems very related.  At the
same time, I can also see how people would disagree.

I'm traveling until May 23.  I can resend this.  Probably as two patches
for simpler review.

regards,
dan carpenter

On Wed, May 15, 2024 at 04:50:48PM +0200, Dan Carpenter wrote:
> On Sun, May 12, 2024 at 12:01:55PM -0400, Michael S. Tsirkin wrote:
> > On Fri, May 10, 2024 at 03:50:45PM +0300, Dan Carpenter wrote:
> > > The virtnet_send_command_reply() function returns true on success or
> > > false on failure.  The "ok" variable is true/false depending on whether
> > > it succeeds or not.  It's up to the caller to translate the true/false
> > > into -EINVAL on failure or zero for success.
> > > 
> > > The bug is that __virtnet_get_hw_stats() returns false for both
> > > errors and success.  It's not a bug, but it is confusing that the caller
> > > virtnet_get_hw_stats() uses an "ok" variable to store negative error
> > > codes.
> > 
> > The bug is ... It's not a bug ....
> > 
> > I think what you are trying to say is that the error isn't
> > really handled anyway, except for printing a warning,
> > so it's not a big deal.
> > 
> > Right?
> > 
> 
> No, I'm sorry, that was confusing.  The change to __virtnet_get_hw_stats()
> is a bugfix but the change to virtnet_get_hw_stats() was not a bugfix.
> I viewed this all as really one thing, because it's cleaning up the
> error codes which happens to fix a bug.  It seems very related.  At the
> same time, I can also see how people would disagree.
> 
> I'm traveling until May 23.  I can resend this.  Probably as two patches
> for simpler review.
> 
> regards,
> dan carpenter
>  

Yea, no rush - bugfixes are fine after 23. And it's ok to combine into
one - we don't want inconsistent code - just please write a clear
commit log message.


-- 
MST

On Fri, May 10, 2024 at 03:50:45PM +0300, Dan Carpenter wrote:
> The virtnet_send_command_reply() function returns true on success or
> false on failure.  The "ok" variable is true/false depending on whether
> it succeeds or not.  It's up to the caller to translate the true/false
> into -EINVAL on failure or zero for success.
> 
> The bug is that __virtnet_get_hw_stats() returns false for both
> errors and success.  It's not a bug, but it is confusing that the caller
> virtnet_get_hw_stats() uses an "ok" variable to store negative error
> codes.
> 
> Fix the bug and clean things up so that it's clear that
> __virtnet_get_hw_stats() returns zero on success or negative error codes
> on failure.
> 
> Fixes: 941168f8b40e ("virtio_net: support device stats")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Hi Dan, all,

Strictly this is doing two things.  But I agree that the "ok" variable in
virtnet_get_hw_stats() was very confusing, and I'm not sure how long it
would have taken me to grasp the fix without that change being here too.

Reviewed-by: Simon Horman <horms@kernel.org>