From: Kees Cook <firstname.lastname@example.org> To: Thomas Gleixner <email@example.com> Cc: "Gustavo A. R. Silva" <firstname.lastname@example.org>, Alan Cox <email@example.com>, Ingo Molnar <firstname.lastname@example.org>, "H. Peter Anvin" <email@example.com>, X86 ML <firstname.lastname@example.org>, LKML <email@example.com> Subject: Re: [PATCH] x86/syscalls: Mark expected switch fall-throughs Date: Wed, 29 Nov 2017 16:21:20 -0800 [thread overview] Message-ID: <CAGXu5j+S3brOaWYK1P2Y7=RgZDjr3G1ymHhZ=iSg+FxEJduZeQ@mail.gmail.com> (raw) In-Reply-To: <alpine.DEB.2.20.1711291612580.1825@nanos> On Wed, Nov 29, 2017 at 7:14 AM, Thomas Gleixner <firstname.lastname@example.org> wrote: > On Wed, 29 Nov 2017, Gustavo A. R. Silva wrote: >> Quoting Thomas Gleixner <email@example.com>: >> >> > >> > So I have to ask WHY this information was not in the changelog of the patch >> > in question: >> > >> > 1) How it works >> > >> > 2) Why comments have been chosen over macros >> > >> >> I will add this info and send the patch again. >> >> > > In preparation to enabling -Wimplicit-fallthrough, mark switch cases >> > > where we are expecting to fall through. >> > >> > It's not a reviewers job to chase that information down. >> > >> > While I can understand that the comments are intentional due to existing >> > tools, I still prefer the macro/annotation. But I'm not religious about it >> > when there is common consensus. :) > > ^^^^^^^^^^^^^^^^ > > This is the important point. And there are people aside of me who prefer the > macro annotation. Understood. I, too, prefer the macro annotation, but when considering where the primary benefit comes from, I had to admit that using the comments was tolerable: the many external tools (e.g. Coverity, Eclipse, gcc, clang, etc) that already process the comments means we gain their coverage without any additional work to teach them about yet another way to mark fall-through. In other words, making a marking that only works for humans and gcc leaves out the other tools. To me, "it's ugly" isn't sufficient to limit the wider benefit. And I do recognize that when we get all fixes landed and we add -Wimplicit-fallthrough, then we can just ignore the tools that don't understand the new marking and announce false positives: but it's not worth everyone else's time to deal with those false positives. There is already a solution that all "missing break" tools handle, so let's use it, all false positives vanish, and everyone wins (with a small "ugliness" cost). -Kees -- Kees Cook Pixel Security
next prev parent reply other threads:[~2017-11-30 0:21 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-11-27 23:52 Gustavo A. R. Silva 2017-11-28 13:49 ` Thomas Gleixner 2017-11-28 18:05 ` Gustavo A. R. Silva 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 [this message] 2019-01-29 23:56 Gustavo A. R. Silva 2019-01-30 0:14 ` Thomas Gleixner
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