Linux Ethernet Bridging - Nov 2018 - [Bridge] [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 at lunn.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

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

On Sat, Nov 24, 2018 at 06:18:33PM +0200, nikolay at cumulusnetworks.com
wrote:
> On 24 November 2018 18:10:41 EET, Andrew Lunn <andrew at lunn.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. 
O.K, i was trying to make it easier to see which option caused it to
happen.
> >> +	}
> >> +
> >> +	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. 
Well, the caller can check to see if extack is present, even on
success. This is extack, not extnack after all...

	 Andrew