linux-kernel - Re: [PATCH] arm64: fix unreachable code issue with cmpxchg

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Message-ID: <20190910034249.GA1673@archlinux-threadripper>
Date:   Mon, 9 Sep 2019 20:42:49 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Andrew Murray <andrew.murray@....com>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] arm64: fix unreachable code issue with cmpxchg

On Mon, Sep 09, 2019 at 10:21:35PM +0200, Arnd Bergmann wrote:
> On arm64 build with clang, sometimes the __cmpxchg_mb is not inlined
> when CONFIG_OPTIMIZE_INLINING is set.
> Clang then fails a compile-time assertion, because it cannot tell at
> compile time what the size of the argument is:
> 
> mm/memcontrol.o: In function `__cmpxchg_mb':
> memcontrol.c:(.text+0x1a4c): undefined reference to `__compiletime_assert_175'
> memcontrol.c:(.text+0x1a4c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `__compiletime_assert_175'
> 
> Mark all of the cmpxchg() style functions as __always_inline to
> ensure that the compiler can see the result.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Nathan Chancellor <natechancellor@...il.com>
Tested-by: Nathan Chancellor <natechancellor@...il.com>