From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH] x86/syscalls: Mark expected switch fall-throughs
Date: Tue, 28 Nov 2017 12:05:12 -0600 [thread overview]
Message-ID: <20171128120512.Horde.1mz61Up1PsNtyHbrjWmK8L7@gator4166.hostgator.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1711281448520.1723@nanos>
Quoting Thomas Gleixner <tglx@linutronix.de>:
> On Mon, 27 Nov 2017, Gustavo A. R. Silva wrote:
>
>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>> where we are expecting to fall through.
>
>> case 0:
>> if (!n--) break;
>> *args++ = regs->bx;
>> + /* fall through */
>
> And these gazillions of pointless comments help enabling of
> -Wimplicit-fallthrough in which way?
>
The -Wimplicit-fallthrough option was added to GCC 7. We want to add
that option to the top-level Makefile so we can have the compiler help
us not make mistakes as missing "break"s or "continue"s. This also
documents the intention for humans and provides a way for analyzers to
report issues or ignore False Positives.
So prior to adding such option to the Makefile, we have to properly
add a code comment wherever the code is intended to fall through.
During the process of placing these comments I have identified actual
bugs (missing "break"s/"continue"s) in a variety of components in the
kernel, so I think this effort is valuable. Lastly, such a simple
comment in the code can save a person plenty of time during a code
review.
Thanks
--
Gustavo A. R. Silva
next prev parent reply other threads:[~2017-11-28 18:05 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-27 23:52 [PATCH] x86/syscalls: Mark expected switch fall-throughs Gustavo A. R. Silva
2017-11-28 13:49 ` Thomas Gleixner
2017-11-28 18:05 ` Gustavo A. R. Silva [this message]
2017-11-28 18:10 ` Thomas Gleixner
2017-11-28 18:17 ` Thomas Gleixner
2017-11-28 18:22 ` Gustavo A. R. Silva
2017-11-28 18:27 ` Thomas Gleixner
2017-11-28 18:35 ` Thomas Gleixner
2017-11-28 18:45 ` Thomas Gleixner
2017-11-28 18:53 ` Gustavo A. R. Silva
2017-11-28 19:48 ` Thomas Gleixner
2017-11-28 19:00 ` Alan Cox
2017-11-28 19:10 ` Linus Torvalds
2017-11-28 19:59 ` Joe Perches
2017-11-28 20:08 ` Thomas Gleixner
2017-11-28 20:34 ` Kees Cook
2017-11-28 20:37 ` Gustavo A. R. Silva
2017-11-29 1:07 ` Joe Perches
2017-11-29 8:20 ` Geert Uytterhoeven
2017-11-28 20:11 ` Thomas Gleixner
2017-11-28 20:25 ` Gustavo A. R. Silva
2017-11-28 21:25 ` Thomas Gleixner
2017-11-29 15:10 ` Gustavo A. R. Silva
2017-11-29 15:14 ` Thomas Gleixner
2017-11-30 0:21 ` Kees Cook
2019-01-29 23:56 Gustavo A. R. Silva
2019-01-30 0:14 ` Thomas Gleixner
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