netdev - Re: [PATCH net-next v2 1/3] net: bridge: add support for user-controlled bool options

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Message-ID: <66D818AF-A45E-41B3-AC9C-90A7E607FD2D@cumulusnetworks.com>
Date:   Sat, 24 Nov 2018 18:18:33 +0200
From:   nikolay@...ulusnetworks.com
To:     Andrew Lunn <andrew@...n.ch>
CC:     netdev@...r.kernel.org, roopa@...ulusnetworks.com,
        davem@...emloft.net, bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next v2 1/3] net: bridge: add support for user-controlled bool options

On 24 November 2018 18:10:41 EET, Andrew Lunn <andrew@...n.ch> wrote:
>> +int br_boolopt_toggle(struct net_bridge *br, enum br_boolopt_id opt,
>bool on,
>> +		      struct netlink_ext_ack *extack)
>> +{
>> +	switch (opt) {
>> +	default:
>> +		/* shouldn't be called with unsupported options */
>> +		WARN_ON(1);
>> +		break;
>
>So you return 0 here, meaning the br_debug() lower down will not
>happen. Maybe return -EOPNOTSUPP?
>

No, the idea here is that some option in the future might return an error. 
This function cannot be called with unsupported option thus the warn. 

>> +	}
>> +
>> +	return 0;
>> +}
>> +
>
>> +int br_boolopt_multi_toggle(struct net_bridge *br,
>> +			    struct br_boolopt_multi *bm,
>> +			    struct netlink_ext_ack *extack)
>> +{
>> +	unsigned long bitmap = bm->optmask;
>> +	int err = 0;
>> +	int opt_id;
>> +
>> +	for_each_set_bit(opt_id, &bitmap, BR_BOOLOPT_MAX) {
>> +		bool on = !!(bm->optval & BIT(opt_id));
>> +
>> +		err = br_boolopt_toggle(br, opt_id, on, extack);
>> +		if (err) {
>> +			br_debug(br, "boolopt multi-toggle error: option: %d current: %d
>new: %d error: %d\n",
>> +				 opt_id, br_boolopt_get(br, opt_id), on, err);
>> +			break;
>> +		}
>> +	}
>
>Does the semantics of extack allow you to return something even when
>there is no error? If there are bits > BR_BOOLOPT_MAX you could return
>0, but also add a warning in extack that some bits where not supported
>by this kernel.

If we return 0 there's no reason to check extack. 

>> +void br_boolopt_multi_get(const struct net_bridge *br,
>> +			  struct br_boolopt_multi *bm)
>> +{
>> +	u32 optval = 0;
>> +	int opt_id;
>> +
>> +	for (opt_id = 0; opt_id < BR_BOOLOPT_MAX; opt_id++)
>> +		optval |= (br_boolopt_get(br, opt_id) << opt_id);
>> +
>> +	bm->optval = optval;
>> +	bm->optmask = 0;
>
>You liked the idea of setting optmask to indicate which bits this
>kernel supports. Did you change your mind?
>

Please see patch 03.

>       Andrew


-- 
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