netdev - Re: [PATCH net-next] net: drop the weight argument from netif_napi

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Date:   Tue, 27 Sep 2022 11:38:36 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Paolo Abeni <pabeni@...hat.com>,
        kvalo@...nel.org, Johannes Berg <johannes@...solutions.net>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        linux-can@...r.kernel.org, Jiri Pirko <jiri@...nulli.us>
Subject: Re: [PATCH net-next] net: drop the weight argument from netif_napi_add

On Tue, Sep 27, 2022 at 11:18 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Tue, 27 Sep 2022 10:54:49 -0700 Eric Dumazet wrote:
> > On Tue, Sep 27, 2022 at 6:28 AM Jakub Kicinski <kuba@...nel.org> wrote:
> > > We tell driver developers to always pass NAPI_POLL_WEIGHT
> > > as the weight to netif_napi_add(). This may be confusing
> > > to newcomers, drop the weight argument, those who really
> > > need to tweak the weight can use netif_napi_add_weight().
> > >
> > > Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> >
> > Sure, but this kind of patch makes backports harder.
> > Not sure how confused are newcomers about this NAPI_POLL_WEIGHT....
>
> I maintained this patch in my tree for a couple of releases (because
> I was waiting for the _weight() version to propagate to non-netdev
> trees) and the conflicts were minor. Three or so cases of new features
> added to drivers which touched the NAPI calls (WiFi and embedded) and
> the strlcpy -> strscpy patch, and, well, why did we take that in if we
> worry about backports...
>
> NAPI weight was already dead when I started hacking on the kernel
> 10 years ago. I don't think it's reasonable to keep dead stuff
> in our APIs for backport's sake. Adding Jiri to CC in case I need
> someone to back me up :)
>
> The idea for this patch came because I was reviewing a driver which
> was trying to do something clever with the weight.
>

No hard feelings, but the recent removal of netif_tx_napi_add() added
extra work for some of us ;)

Keeping around few helpers to keep API a bit stable would help I think.