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Thu, 26 Jan 2023 10:57:21 +0100 (CET) Received: from tellis.lin.mbt.kalray.eu (unknown [192.168.36.206]) by zimbra2.kalray.eu (Postfix) with ESMTPSA id 9A5BE27E048E; Thu, 26 Jan 2023 10:57:21 +0100 (CET) X-Virus-Scanned: E-securemail Secumail-id: <1f18.63d24e82.905d3.0> DKIM-Filter: OpenDKIM Filter v2.10.3 zimbra2.kalray.eu 11B4E27E0492 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kalray.eu; s=32AE1B44-9502-11E5-BA35-3734643DEF29; t=1674727042; bh=y0pU6bUB9NtRwjLHJtgOZpwuFzZAZbLkd/6NSd04WhM=; h=Date:From:To:Message-ID:MIME-Version; b=X7BuUXlibp43NQwoW2XoKczIL4vzGNFTCj5F8yW370vweqIXc9XTSGMKEFeNuiA5e bkUAd/wPpBSOBVN1KkeOkTfHQXjfCuCp1M/EQOs9zosEydOfE9WuKyG1Bj/44r3wGZ mysuu23qG+bNP9s2Himt9ysP+5Wj3jljQFPyrv34= Date: Thu, 26 Jan 2023 10:57:20 +0100 From: Jules Maselbas To: Mark Rutland Cc: Yann Sionneau , Arnd Bergmann , Jonathan Corbet , Thomas Gleixner , Marc Zyngier , Rob Herring , Krzysztof Kozlowski , Will Deacon , Peter Zijlstra , Boqun Feng , Eric Biederman , Kees Cook , Oleg Nesterov , Ingo Molnar , Waiman Long , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Paul Moore , Eric Paris , Christian Brauner , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guillaume Thouvenin , Clement Leger , Vincent Chardon , Marc =?utf-8?b?UG91bGhpw6hz?= , Julian Vetter , Samuel Jones , Ashley Lesdalons , Thomas Costis , Marius Gligor , Jonathan Borne , Julien Villette , Luc Michel , Louis Morhet , Julien Hascoet , Jean-Christophe Pince , Guillaume Missonnier , Alex Michon , Huacai Chen , WANG Xuerui , Shaokun Zhang , John Garry , Guangbin Huang , Bharat Bhushan , Bibo Mao , Atish Patra , "Jason A. Donenfeld" , Qi Liu , Jiaxun Yang , Catalin Marinas , Mark Brown , Janosch Frank , Alexey Dobriyan , Benjamin Mugnier , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-audit@redhat.com, linux-riscv@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [RFC PATCH v2 11/31] kvx: Add atomic/locking headers Message-ID: <20230126095720.GF5952@tellis.lin.mbt.kalray.eu> References: <20230120141002.2442-1-ysionneau@kalray.eu> <20230120141002.2442-12-ysionneau@kalray.eu> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-ALTERMIMEV2_out: done X-Stat-Signature: gfieg59u9e9zbrwmy5bcdjpahzzu9p6o X-Rspam-User: X-Rspamd-Queue-Id: AE06A180014 X-Rspamd-Server: rspam06 X-HE-Tag: 1674727046-570334 X-HE-Meta: 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 AGQEishN 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Mark, On Fri, Jan 20, 2023 at 03:18:48PM +0000, Mark Rutland wrote: > On Fri, Jan 20, 2023 at 03:09:42PM +0100, Yann Sionneau wrote: > > Add common headers (atomic, bitops, barrier and locking) for basic > > kvx support. > > > > Co-developed-by: Clement Leger > > Signed-off-by: Clement Leger > > Co-developed-by: Jules Maselbas > > Signed-off-by: Jules Maselbas > > Co-developed-by: Julian Vetter > > Signed-off-by: Julian Vetter > > Co-developed-by: Julien Villette > > Signed-off-by: Julien Villette > > Co-developed-by: Yann Sionneau > > Signed-off-by: Yann Sionneau > > --- > > > > Notes: > > V1 -> V2: > > - use {READ,WRITE}_ONCE for arch_atomic64_{read,set} > > - use asm-generic/bitops/atomic.h instead of __test_and_*_bit > > - removed duplicated includes > > - rewrite xchg and cmpxchg in C using builtins for acswap insn > > Thanks for those changes. I see one issue below (instantiated a few times), but > other than that this looks good to me. > > [...] > > > +#define ATOMIC64_RETURN_OP(op, c_op) \ > > +static inline long arch_atomic64_##op##_return(long i, atomic64_t *v) \ > > +{ \ > > + long new, old, ret; \ > > + \ > > + do { \ > > + old = v->counter; \ > > This should be arch_atomic64_read(v), in order to avoid the potential for the > compiler to replay the access and introduce ABA races and other such problems. Thanks for the suggestion, this will be into v3. > For details, see: > > https://lore.kernel.org/lkml/Y70SWXHDmOc3RhMd@osiris/ > https://lore.kernel.org/lkml/Y71LoCIl+IFdy9D8@FVFF77S0Q05N/ > > I see that the generic 32-bit atomic code suffers from that issue, and we > should fix it. I took a look at the generic 32-bit atomic, but I am unsure if this needs to be done for both the SMP and non-SMP implementations. But I can send a first patch and we can discuss from there. > > + new = old c_op i; \ > > + ret = arch_cmpxchg(&v->counter, old, new); \ > > + } while (ret != old); \ > > + \ > > + return new; \ > > +} > > + > > +#define ATOMIC64_OP(op, c_op) \ > > +static inline void arch_atomic64_##op(long i, atomic64_t *v) \ > > +{ \ > > + long new, old, ret; \ > > + \ > > + do { \ > > + old = v->counter; \ > > Likewise, arch_atomic64_read(v) here. ack > > + new = old c_op i; \ > > + ret = arch_cmpxchg(&v->counter, old, new); \ > > + } while (ret != old); \ > > +} > > + > > +#define ATOMIC64_FETCH_OP(op, c_op) \ > > +static inline long arch_atomic64_fetch_##op(long i, atomic64_t *v) \ > > +{ \ > > + long new, old, ret; \ > > + \ > > + do { \ > > + old = v->counter; \ > > Likewise, arch_atomic64_read(v) here. ack > > + new = old c_op i; \ > > + ret = arch_cmpxchg(&v->counter, old, new); \ > > + } while (ret != old); \ > > + \ > > + return old; \ > > +} > > + > > +#define ATOMIC64_OPS(op, c_op) \ > > + ATOMIC64_OP(op, c_op) \ > > + ATOMIC64_RETURN_OP(op, c_op) \ > > + ATOMIC64_FETCH_OP(op, c_op) > > + > > +ATOMIC64_OPS(and, &) > > +ATOMIC64_OPS(or, |) > > +ATOMIC64_OPS(xor, ^) > > +ATOMIC64_OPS(add, +) > > +ATOMIC64_OPS(sub, -) > > + > > +#undef ATOMIC64_OPS > > +#undef ATOMIC64_FETCH_OP > > +#undef ATOMIC64_OP > > + > > +static inline int arch_atomic_add_return(int i, atomic_t *v) > > +{ > > + int new, old, ret; > > + > > + do { > > + old = v->counter; > > Likewise, arch_atomic64_read(v) here. ack, this will bt arch_atomic_read(v) here since this is not atomic64_t here. Thanks -- Jules