Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <cover.1605896059.git.gustavoars@kernel.org> <20201120105344.4345c14e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
 <202011201129.B13FDB3C@keescook> <20201120115142.292999b2@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
 <202011220816.8B6591A@keescook> <9b57fd4914b46f38d54087d75e072d6e947cb56d.camel@HansenPartnership.com>
 <CANiq72nZrHWTA4_Msg6MP9snTyenC6-eGfD27CyfNSu7QoVZbw@mail.gmail.com> <1c7d7fde126bc0acf825766de64bf2f9b888f216.camel@HansenPartnership.com>
In-Reply-To: <1c7d7fde126bc0acf825766de64bf2f9b888f216.camel@HansenPartnership.com>
From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Mon, 23 Nov 2020 15:19:55 +0100
Message-ID: <CANiq72m22Jb5_+62NnwX8xds2iUdWDMAqD8PZw9cuxdHd95W0A@mail.gmail.com>
Subject: Re: [PATCH 000/141] Fix fall-through warnings for Clang
To:     James Bottomley <James.Bottomley@hansenpartnership.com>
Cc:     Kees Cook <keescook@chromium.org>,
        Jakub Kicinski <kuba@kernel.org>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        alsa-devel@alsa-project.org, amd-gfx@lists.freedesktop.org,
        bridge@lists.linux-foundation.org, ceph-devel@vger.kernel.org,
        cluster-devel@redhat.com, coreteam@netfilter.org,
        devel@driverdev.osuosl.org, dm-devel@redhat.com,
        drbd-dev@lists.linbit.com, dri-devel@lists.freedesktop.org,
        GR-everest-linux-l2@marvell.com, GR-Linux-NIC-Dev@marvell.com,
        intel-gfx@lists.freedesktop.org, intel-wired-lan@lists.osuosl.org,
        keyrings@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
        linux-acpi@vger.kernel.org, linux-afs@lists.infradead.org,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-arm-msm@vger.kernel.org,
        linux-atm-general@lists.sourceforge.net,
        linux-block@vger.kernel.org, linux-can@vger.kernel.org,
        linux-cifs@vger.kernel.org,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        linux-decnet-user@lists.sourceforge.net,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        linux-fbdev@vger.kernel.org, linux-geode@lists.infradead.org,
        linux-gpio@vger.kernel.org, linux-hams@vger.kernel.org,
        linux-hwmon@vger.kernel.org, linux-i3c@lists.infradead.org,
        linux-ide@vger.kernel.org, linux-iio@vger.kernel.org,
        linux-input <linux-input@vger.kernel.org>,
        linux-integrity@vger.kernel.org,
        linux-mediatek@lists.infradead.org,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
        linux-mmc@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
        linux-mtd@lists.infradead.org, linux-nfs@vger.kernel.org,
        linux-rdma@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
        linux-scsi@vger.kernel.org, linux-sctp@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-usb@vger.kernel.org, linux-watchdog@vger.kernel.org,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        netfilter-devel@vger.kernel.org, nouveau@lists.freedesktop.org,
        op-tee@lists.trustedfirmware.org, oss-drivers@netronome.com,
        patches@opensource.cirrus.com, rds-devel@oss.oracle.com,
        reiserfs-devel@vger.kernel.org, samba-technical@lists.samba.org,
        selinux@vger.kernel.org, target-devel@vger.kernel.org,
        tipc-discussion@lists.sourceforge.net,
        usb-storage@lists.one-eyed-alien.net,
        virtualization@lists.linux-foundation.org,
        wcn36xx@lists.infradead.org,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        xen-devel@lists.xenproject.org, linux-hardening@vger.kernel.org,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Miguel Ojeda <ojeda@kernel.org>, Joe Perches <joe@perches.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Sun, Nov 22, 2020 at 11:36 PM James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
>
> Well, it seems to be three years of someone's time plus the maintainer
> review time and series disruption of nearly a thousand patches.  Let's
> be conservative and assume the producer worked about 30% on the series
> and it takes about 5-10 minutes per patch to review, merge and for
> others to rework existing series.  So let's say it's cost a person year
> of a relatively junior engineer producing the patches and say 100h of
> review and application time.  The latter is likely the big ticket item
> because it's what we have in least supply in the kernel (even though
> it's 20x vs the producer time).

How are you arriving at such numbers? It is a total of ~200 trivial lines.

> It's not about the risk of the changes it's about the cost of
> implementing them.  Even if you discount the producer time (which
> someone gets to pay for, and if I were the engineering manager, I'd be
> unhappy about), the review/merge/rework time is pretty significant in
> exchange for six minor bug fixes.  Fine, when a new compiler warning
> comes along it's certainly reasonable to see if we can benefit from it
> and the fact that the compiler people think it's worthwhile is enough
> evidence to assume this initially.  But at some point you have to ask
> whether that assumption is supported by the evidence we've accumulated
> over the time we've been using it.  And if the evidence doesn't support
> it perhaps it is time to stop the experiment.

Maintainers routinely review 1-line trivial patches, not to mention
internal API changes, etc.

If some company does not want to pay for that, that's fine, but they
don't get to be maintainers and claim `Supported`.

Cheers,
Miguel