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Subject: Re: [PATCH] x86/process: Silence KASAN warnings in get_wchan()
To: Andy Lutomirski <luto@amacapital.net>, Ingo Molnar <mingo@kernel.org>
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Date: Wed, 7 Oct 2015 11:54:42 +0300
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On 10/06/2015 09:11 PM, Andy Lutomirski wrote:
> 
> But what's wrong with the GCC attribute mechanism?  Surely GCC ought
> to be able to generate the code, at least in the simple cases, and the
> attribute already exists.  The attribute and READ_ONCE_NOCHECK seem
> like the least messy in the C code.

The problem with 'no_sanitize_address' attribute is incompatibility with inlining. 
GCC can't inline function with that attribute into function without it.
And the contrary is also true - GCC can't inline function without attribute into function with such attribute.

Failure to inline always_inline function leads to build failure.
And under CONFIG_OPTIMIZE=n 'inline' means 'always_inline'.

include/linux/compiler-gcc.h:

#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) ||		\
    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
#define inline		inline		__attribute__((always_inline)) notrace