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

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Message-ID: <CAEA6p_Bwd=Zodzp3H6vjrmGjtPvQWCmj9efsb1QX2mHEtj50JQ@mail.gmail.com>
Date:   Mon, 14 Dec 2020 10:02:01 -0800
From:   Wei Wang <weiwan@...gle.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <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 Sat, Dec 12, 2020 at 2:59 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> 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.

OK. Will move it.

>
> (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;
> > +}