Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <ea83e4d6227b70ae4731c2bfcd727e3afeac3bf8.camel@kernel.crashing.org>
Subject: Re: [PATCH] drivers/macintosh/smu.c: Mark expected switch
 fall-through
From:   Benjamin Herrenschmidt <benh@kernel.crashing.org>
To:     Kees Cook <keescook@chromium.org>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     Stephen Rothwell <sfr@canb.auug.org.au>,
        PowerPC <linuxppc-dev@lists.ozlabs.org>,
        "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
        Linux kernel Mailing List <linux-kernel@vger.kernel.org>
Date:   Tue, 30 Jul 2019 13:37:50 -0700
In-Reply-To: <201907301005.0661E63CF@keescook>
References: <20190730143704.060a2606@canb.auug.org.au>
         <878ssfzjdk.fsf@concordia.ellerman.id.au> <201907301005.0661E63CF@keescook>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, 2019-07-30 at 10:07 -0700, Kees Cook wrote:
> 
> > Why do we think it's an expected fall through? I can't really
> > convince
> > myself from the surrounding code that it's definitely intentional.
> 
> Yeah, good question. Just now when I went looking for who
> used SMU_I2C_TRANSFER_COMBINED, I found the only caller in
> arch/powerpc/platforms/powermac/low_i2c.c and it is clearly using a
> fall-through for building the command for "stdsub" and "combined",
> so I think that's justification enough:

Yes, sorry for the delay, the fall through is intentional.

Cheers,
Ben.