linux-hardening - Re: [PATCH RESEND][next] rtl8xxxu: Fix fall-through warnings for Clang

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Date:   Thu, 11 Mar 2021 09:00:03 +0200
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Jes Sorensen <Jes.Sorensen@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH RESEND][next] rtl8xxxu: Fix fall-through warnings for Clang

Kees Cook <keescook@...omium.org> writes:

> On Fri, Mar 05, 2021 at 03:40:33PM +0200, Kalle Valo wrote:
>> "Gustavo A. R. Silva" <gustavoars@...nel.org> writes:
>> 
>> > In preparation to enable -Wimplicit-fallthrough for Clang, fix
>> > multiple warnings by replacing /* fall through */ comments with
>> > the new pseudo-keyword macro fallthrough; instead of letting the
>> > code fall through to the next case.
>> >
>> > Notice that Clang doesn't recognize /* fall through */ comments as
>> > implicit fall-through markings.
>> >
>> > Link: https://github.com/KSPP/linux/issues/115
>> > Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
>> 
>> It's not cool that you ignore the comments you got in [1], then after a
>> while mark the patch as "RESEND" and not even include a changelog why it
>> was resent.
>> 
>> [1] https://patchwork.kernel.org/project/linux-wireless/patch/d522f387b2d0dde774785c7169c1f25aa529989d.1605896060.git.gustavoars@kernel.org/
>
> Hm, this conversation looks like a miscommunication, mainly? I see
> Gustavo, as requested by many others[1], replacing the fallthrough
> comments with the "fallthrough" statement. (This is more than just a
> "Clang doesn't parse comments" issue.)

v1 was clearly rejected by Jes, so sending a new version without any
changelog or comments is not the way to go. The changelog shoud at least
have had "v1 was rejected but I'm resending this again because <insert
reason here>" or something like that to make it clear what's happening.

> This could be a tree-wide patch and not bother you, but Greg KH has
> generally advised us to send these changes broken out. Anyway, this
> change still needs to land, so what would be the preferred path? I think
> Gustavo could just carry it for Linus to merge without bothering you if
> that'd be preferred?

I agree with Greg. Please don't do cleanups like this via another tree
as that just creates more work due to conflicts between the trees, which
is a lot more annoying to deal with than applying few patches. But when
submitting patches please follow the rules, don't cut corners.

Jes, I don't like 'fallthrough' either and prefer the original comment,
but the ship has sailed on this one. Maybe we should just take it?

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches