netdev - Re: [PATCH net-next v5 1/5] netlink: extended ACK reporting

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Date:   Wed, 12 Apr 2017 17:13:03 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     David Ahern <dsa@...ulusnetworks.com>
Cc:     Johannes Berg <johannes@...solutions.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        pablo@...filter.org, Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Benc <jbenc@...hat.com>,
        Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH net-next v5 1/5] netlink: extended ACK reporting

Wed, Apr 12, 2017 at 05:06:48PM CEST, dsa@...ulusnetworks.com wrote:
>On 4/12/17 6:34 AM, Johannes Berg wrote:
>> diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
>> index b2c9c26ea30f..7df88770e029 100644
>> --- a/include/uapi/linux/netlink.h
>> +++ b/include/uapi/linux/netlink.h
>> @@ -69,6 +69,10 @@ struct nlmsghdr {
>>  #define NLM_F_CREATE	0x400	/* Create, if it does not exist	*/
>>  #define NLM_F_APPEND	0x800	/* Add to end of list		*/
>>  
>> +/* Flags for ACK message */
>> +#define NLM_F_CAPPED	0x100	/* request was capped */
>> +#define NLM_F_ACK_TLVS	0x200	/* extended ACK TVLs were included */
>> +
>>  /*
>>     4.4BSD ADD		NLM_F_CREATE|NLM_F_EXCL
>>     4.4BSD CHANGE	NLM_F_REPLACE
>> @@ -101,6 +105,33 @@ struct nlmsghdr {
>>  struct nlmsgerr {
>>  	int		error;
>>  	struct nlmsghdr msg;
>> +	/*
>> +	 * followed by the message contents unless NETLINK_CAP_ACK was set
>> +	 * or the ACK indicates success (error == 0)
>> +	 * message length is aligned with NLMSG_ALIGN()
>> +	 */
>> +	/*
>> +	 * followed by TLVs defined in enum nlmsgerr_attrs
>> +	 * if NETLINK_EXT_ACK was set
>> +	 */
>> +};
>> +
>> +/**
>> + * enum nlmsgerr_attrs - nlmsgerr attributes
>> + * @NLMSGERR_ATTR_UNUSED: unused
>> + * @NLMSGERR_ATTR_MSG: error message string (string)
>> + * @NLMSGERR_ATTR_OFFS: offset of the invalid attribute in the original
>> + *	 message, counting from the beginning of the header (u32)
>> + * @__NLMSGERR_ATTR_MAX: number of attributes
>> + * @NLMSGERR_ATTR_MAX: highest attribute number
>> + */
>> +enum nlmsgerr_attrs {
>> +	NLMSGERR_ATTR_UNUSED,
>> +	NLMSGERR_ATTR_MSG,
>
>There was a discussion about side effects of adding strings (bloat,
>internationalization). Should ATTR_MSG be removed until that is ironed
>out? Leaving it in suggests it is ok to start adding strings.

I believe that we need strings right away. Without them, this patchset
really does not make much sense.