linux-kernel - Re: [PATCH] x86/process: Silence KASAN warnings in get

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Message-ID: <20151005163906.GE26924@tassilo.jf.intel.com>
Date:	Mon, 5 Oct 2015 09:39:06 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:	Dmitry Vyukov <dvyukov@...gle.com>, Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"x86@...nel.org" <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Andrey Konovalov <andreyknvl@...gle.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	kasan-dev <kasan-dev@...glegroups.com>,
	Borislav Petkov <bp@...en8.de>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Wolfram Gloger <wmglo@...t.med.uni-muenchen.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] x86/process: Silence KASAN warnings in get_wchan()

> But, I think I have the solution.
> We could have some blacklist - list of function names which we should be ignored.
> In kasan_report() we could resolve return address to function name and compare it with name in list.
> If name in list -> ignore report.

I think annotating statements is cleaner than functions, even if it
is more code. Much better documentation

But if you really want to annotate on the function level:

It's better to annotate the function directly than some hidden away list.
This way there is some indication that there are races in there, which is
generally useful documentation.

__racy_function or similar.

Also central lists are generally annoying as they cause patch conflicts.

If disabling with an attribute doesn't work, you could put it into a special section
with __attribute__((section ...)) and check the start/end symbol before reporting. 
That's how kprobes solves similar issues. It also has the advantage
that it stops inlining.

-Andi
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