netdev - Re: [PATCH net-next v4 3/3] net: add sysfs attribute to control napi threaded mode

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Date:   Sat, 12 Dec 2020 14:59:02 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Wei Wang <weiwan@...gle.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        Paolo Abeni <pabeni@...hat.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Felix Fietkau <nbd@....name>, Hillf Danton <hdanton@...a.com>
Subject: Re: [PATCH net-next v4 3/3] net: add sysfs attribute to control
 napi threaded mode

On Tue,  8 Dec 2020 16:54:44 -0800 Wei Wang wrote:
> +static void dev_disable_threaded_all(struct net_device *dev)
> +{
> +	struct napi_struct *napi;
> +
> +	list_for_each_entry(napi, &dev->napi_list, dev_list)
> +		napi_set_threaded(napi, false);
> +}

This is an implementation detail which should be hidden in dev.c IMHO.
Since the sysfs knob is just a device global on/off the iteration over
napis and all is best hidden away.

(sorry about the delayed review BTW, hope we can do a minor revision
and still hit 5.12)

> +static int modify_napi_threaded(struct net_device *dev, unsigned long val)
> +{
> +	struct napi_struct *napi;
> +	int ret;
> +
> +	if (list_empty(&dev->napi_list))
> +		return -EOPNOTSUPP;
> +
> +	list_for_each_entry(napi, &dev->napi_list, dev_list) {
> +		ret = napi_set_threaded(napi, !!val);
> +		if (ret) {
> +			/* Error occurred on one of the napi,
> +			 * reset threaded mode on all napi.
> +			 */
> +			dev_disable_threaded_all(dev);
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}