linux-kernel - Re: [PATCH v2 00/10] Rework READ

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Message-ID: <7436.1580466021@warthog.procyon.org.uk>
Date:   Fri, 31 Jan 2020 10:20:21 +0000
From:   David Howells <dhowells@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     dhowells@...hat.com, Will Deacon <will@...nel.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Peter Zijlstra <peterz@...radead.org>,
        Segher Boessenkool <segher@...nel.crashing.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH v2 00/10] Rework READ_ONCE() to improve codegen

Of course, if you're feeling adventurous and willing to at least entertain the
mere speculation of switching the kernel source to C++, we could then use
inline template functions:

	template <typename T>
	static inline T __READ_ONCE(T &var)
	{
		T val = *(const volatile T *)&var;
		return val;
	}

	template <typename T>
	static inline T READ_ONCE(T &var)
	{
		T val;
		compiletime_assert_rwonce_type(var);
		val = __READ_ONCE(var);
		smp_read_barrier_depends();
		return val;
	}

Of course, that would mean using C++...

David