linux-kernel - Re: [PATCH v2] init: Do not select DEBUG

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Date:   Thu, 11 Apr 2019 15:21:09 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Josh Triplett <josh@...htriplett.org>
Cc:     Sinan Kaya <Okaya@...nel.org>, Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Adrian Reber <adrian@...as.de>,
        Richard Guy Briggs <rgb@...hat.com>,
        Petr Mladek <pmladek@...e.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Robin Murphy <robin.murphy@....com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Changbin Du <changbin.du@...el.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Sam Ravnborg <sam@...nborg.org>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH v2] init: Do not select DEBUG_KERNEL by default

On Thu, Apr 11, 2019 at 3:16 PM Josh Triplett <josh@...htriplett.org> wrote:
>
> On Wed, Apr 10, 2019 at 11:13:52PM -0400, Sinan Kaya wrote:
> > On 4/10/2019 11:02 PM, Josh Triplett wrote:
> > > Then let's fix*that*, and get checkpatch to help enforce it in the future. EXPERT doesn't affect code generation, and neither should this.
> >
> > I think we have to do both. We need to go after the users as well as
> > solve the immediate problem per this patch.
> >
> > As Mathieu identified, CONFIG_DEBUG_KERNEL is being used all over the
> > place and getting subsystem owners to remove let alone add a check
> > to checkpatch is just going to take time.
> >
> > Please let us know if you are OK with this plan.
>
> I'm not OK with this plan. Turning on EXPERT should make the options
> under DEBUG_KERNEL visible; it's a bug that DEBUG_KERNEL affects code
> generation as well.
>
> Proposed alternative plan: let's add a new symbol, something like
> DEBUG_MISC ("Miscellaneous debug code that should be under a more
> specific debug option but isn't"), make it depend on DEBUG_KERNEL and be
> "default DEBUG_KERNEL" but allow itself to be turned off, and then
> mechanically change the small handful of "#ifdef CONFIG_DEBUG_KERNEL" to
> "#ifdef CONFIG_DEBUG_MISC".
>
> Does that sound like an appropriately rapid solution for this bug?

Sure, that sounds fine to me. Sinan can you take care of that for v4?

-- 
Kees Cook