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

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Date:   Sat, 24 Nov 2018 17:10:41 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
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

> +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?

> +	}
> +
> +	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.

> +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?

       Andrew