linux-kernel - Re: [PATCH] sched: Work around undefined behavior in sched class checking

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Date:   Wed, 5 May 2021 07:34:42 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
        linux-toolchains@...r.kernel.org
Subject: Re: [PATCH] sched: Work around undefined behavior in sched class
 checking

> > Use RELOC_HIDE to make this work. This hides the symbols from gcc,
> > so the optimizer won't make these assumption. I also split
> > the BUG_ONs in multiple.
> 
> Urgh, that insanity again :/ Can't we pretty please get a GCC flag to
> disable that?

Even if that was done (I could totally see the gcc people pushing back on this;
why should they add special flags just for Linux developers not understanding
ISO-C?) you would still need the fix for already shipping compilers.

-Andi