netdev - Re: [PATCH net] devlink: ignore -EOPNOTSUPP errors on dumpit

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Message-ID: <8f0cce83-4d0d-2230-1727-86f9c7c2ac55@intel.com>
Date:   Tue, 28 Jul 2020 16:21:09 -0700
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Jakub Kicinski <kuba@...nel.org>, davem@...emloft.net
Cc:     netdev@...r.kernel.org, andrew@...n.ch, jiri@...lanox.com,
        kernel-team@...com
Subject: Re: [PATCH net] devlink: ignore -EOPNOTSUPP errors on dumpit



On 7/28/2020 4:15 PM, Jakub Kicinski wrote:
> Number of .dumpit functions try to ignore -EOPNOTSUPP errors.
> Recent change missed that, and started reporting all errors
> but -EMSGSIZE back from dumps. This leads to situation like
> this:
> 
> $ devlink dev info
> devlink answers: Operation not supported
> 
> Dump should not report an error just because the last device
> to be queried could not provide an answer.
> 
> To fix this and avoid similar confusion make sure we clear
> err properly, and not leave it set to an error if we don't
> terminate the iteration.
> 

Makes sense to me.

> Fixes: c62c2cfb801b ("net: devlink: don't ignore errors during dumpit")
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
>  net/core/devlink.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index 2cafbc808b09..1d38b6651b23 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -1065,7 +1065,9 @@ static int devlink_nl_cmd_sb_pool_get_dumpit(struct sk_buff *msg,
>  						   devlink_sb,
>  						   NETLINK_CB(cb->skb).portid,
>  						   cb->nlh->nlmsg_seq);
> -			if (err && err != -EOPNOTSUPP) {
> +			if (err == -EOPNOTSUPP) {
> +				err = 0;
> +			} else if (err) {
>  				mutex_unlock(&devlink->lock);
>  				goto out;
>  			}
> @@ -1266,7 +1268,9 @@ static int devlink_nl_cmd_sb_port_pool_get_dumpit(struct sk_buff *msg,
>  							devlink, devlink_sb,
>  							NETLINK_CB(cb->skb).portid,
>  							cb->nlh->nlmsg_seq);
> -			if (err && err != -EOPNOTSUPP) {
> +			if (err == -EOPNOTSUPP) {
> +				err = 0;
> +			} else if (err) {
>  				mutex_unlock(&devlink->lock);
>  				goto out;
>  			}
> @@ -1498,7 +1502,9 @@ devlink_nl_cmd_sb_tc_pool_bind_get_dumpit(struct sk_buff *msg,
>  							   devlink_sb,
>  							   NETLINK_CB(cb->skb).portid,
>  							   cb->nlh->nlmsg_seq);
> -			if (err && err != -EOPNOTSUPP) {
> +			if (err == -EOPNOTSUPP) {
> +				err = 0;
> +			} else if (err) {
>  				mutex_unlock(&devlink->lock);
>  				goto out;
>  			}
> @@ -3299,7 +3305,9 @@ static int devlink_nl_cmd_param_get_dumpit(struct sk_buff *msg,
>  						    NETLINK_CB(cb->skb).portid,
>  						    cb->nlh->nlmsg_seq,
>  						    NLM_F_MULTI);
> -			if (err && err != -EOPNOTSUPP) {
> +			if (err == -EOPNOTSUPP) {
> +				err = 0;
> +			} else if (err) {
>  				mutex_unlock(&devlink->lock);
>  				goto out;
>  			}
> @@ -3569,7 +3577,9 @@ static int devlink_nl_cmd_port_param_get_dumpit(struct sk_buff *msg,
>  						NETLINK_CB(cb->skb).portid,
>  						cb->nlh->nlmsg_seq,
>  						NLM_F_MULTI);
> -				if (err && err != -EOPNOTSUPP) {
> +				if (err == -EOPNOTSUPP) {
> +					err = 0;
> +				} else if (err) {
>  					mutex_unlock(&devlink->lock);
>  					goto out;
>  				}
> @@ -4518,7 +4528,9 @@ static int devlink_nl_cmd_info_get_dumpit(struct sk_buff *msg,
>  					   cb->nlh->nlmsg_seq, NLM_F_MULTI,
>  					   cb->extack);
>  		mutex_unlock(&devlink->lock);
> -		if (err && err != -EOPNOTSUPP)
> +		if (err == -EOPNOTSUPP)
> +			err = 0;
> +		else if (err)
>  			break;
>  		idx++;
>  	}
>