From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3B14C433B4 for ; Sun, 11 Apr 2021 16:01:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 790FC6105A for ; Sun, 11 Apr 2021 16:01:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236357AbhDKQBl (ORCPT ); Sun, 11 Apr 2021 12:01:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:47270 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236267AbhDKQBk (ORCPT ); Sun, 11 Apr 2021 12:01:40 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 147C061041; Sun, 11 Apr 2021 16:01:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618156884; bh=bxyiUc7lO8RjWeGmFNt0Glxp3nNNC162o0D7XY+vRXg=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=ocbV3yCEonWttAc1zcbh4sFMlpL/8mLiYxvnPxd4vaNWUoxIUghQq/418Vd/8+OsQ uJqpH09JX3FyCKp5XaQYZxmUsBFGWg8DBDqrZUYcGC9eTTDGDZ7Pv1fsnvFz66yY3l CqFgPgBK9ODxn1O/DoS0JWKwm1nNfEok9TRCbissXEHtyCsrFX5+LauK+0HULFJudx MheQDdG6dqOZZtISRGENS7K5+2Yo60vM8RzSwh/VaorG8/XaeVnWmZ6gy7/XASCyPB iuDB+RBHMB+CmVctzSKyVDMGk7JOvcTcXfexy6bCgR4aqAXQUWdHhM9dc/xolI6hq+ ieCqE55bqcOfw== Received: by mail-lj1-f176.google.com with SMTP id m7so1467413ljp.10; Sun, 11 Apr 2021 09:01:23 -0700 (PDT) X-Gm-Message-State: AOAM532GcTgYLIkxzPD48f/zGYs7pN/Gq6XkztodZshTDmn2P86SmLTU JwHCkbiFGWU0dHcCIOW9BoedUCVZZ0aWyXvnE44= X-Google-Smtp-Source: ABdhPJy10CnI96Z9R6HlWIrVpcoYY10s7Y9maxlV3dOVr4CugIJl0sk8MNc8rkDLu53Ak6ongjwa0tUvq8SrIM/7luU= X-Received: by 2002:a05:651c:3c3:: with SMTP id f3mr15178457ljp.105.1618156882398; Sun, 11 Apr 2021 09:01:22 -0700 (PDT) MIME-Version: 1.0 References: <1617201040-83905-1-git-send-email-guoren@kernel.org> <1617201040-83905-5-git-send-email-guoren@kernel.org> In-Reply-To: <1617201040-83905-5-git-send-email-guoren@kernel.org> From: Guo Ren Date: Mon, 12 Apr 2021 00:01:10 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 4/9] csky: locks: Optimize coding convention To: Guo Ren Cc: linux-riscv , Linux Kernel Mailing List , linux-csky@vger.kernel.org, linux-arch , linuxppc-dev@lists.ozlabs.org, linux-xtensa@linux-xtensa.org, openrisc@lists.librecores.org, sparclinux , Guo Ren , Peter Zijlstra , Arnd Bergmann Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Wed, Mar 31, 2021 at 10:32 PM wrote: > > From: Guo Ren > > - Using smp_cond_load_acquire in arch_spin_lock by Peter's > advice. > - Using __smp_acquire_fence in arch_spin_trylock > - Using smp_store_release in arch_spin_unlock > > All above are just coding conventions and won't affect the > function. > > TODO in smp_cond_load_acquire for architecture: > - current csky only has: > lr.w val, > sc.w . val2 > (Any other stores to p0 will let sc.w failed) > > - But smp_cond_load_acquire need: > lr.w val, > wfe > (Any stores to p0 will send the event to let wfe retired) > > Signed-off-by: Guo Ren > Link: https://lore.kernel.org/linux-riscv/CAAhSdy1JHLUFwu7RuCaQ+RUWRBks2KsDva7EpRt8--4ZfofSUQ@mail.gmail.com/T/#m13adac285b7f51f4f879a5d6b65753ecb1a7524e > Cc: Peter Zijlstra > Cc: Arnd Bergmann > --- > arch/csky/include/asm/spinlock.h | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h > index 69f5aa249c5f..69677167977a 100644 > --- a/arch/csky/include/asm/spinlock.h > +++ b/arch/csky/include/asm/spinlock.h > @@ -26,10 +26,8 @@ static inline void arch_spin_lock(arch_spinlock_t *lock) > : "r"(p), "r"(ticket_next) > : "cc"); > > - while (lockval.tickets.next != lockval.tickets.owner) > - lockval.tickets.owner = READ_ONCE(lock->tickets.owner); > - > - smp_mb(); > + smp_cond_load_acquire(&lock->tickets.owner, > + VAL == lockval.tickets.next); It's wrong, we should determine lockval before next read. Fixup: diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h index fe98ad8ece51..2be627ceb9df 100644 --- a/arch/csky/include/asm/spinlock.h +++ b/arch/csky/include/asm/spinlock.h @@ -27,7 +27,8 @@ static inline void arch_spin_lock(arch_spinlock_t *lock) : "r"(p), "r"(ticket_next) : "cc"); - smp_cond_load_acquire(&lock->tickets.owner, + if (lockval.owner != lockval.tickets.next) + smp_cond_load_acquire(&lock->tickets.owner, VAL == lockval.tickets.next); > } > > static inline int arch_spin_trylock(arch_spinlock_t *lock) > @@ -55,15 +53,14 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) > } while (!res); > > if (!contended) > - smp_mb(); > + __smp_acquire_fence(); > > return !contended; > } > > static inline void arch_spin_unlock(arch_spinlock_t *lock) > { > - smp_mb(); > - WRITE_ONCE(lock->tickets.owner, lock->tickets.owner + 1); > + smp_store_release(&lock->tickets.owner, lock->tickets.owner + 1); > } > > static inline int arch_spin_value_unlocked(arch_spinlock_t lock) > -- > 2.17.1 > -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/