From patchwork Thu Apr 26 10:34:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10365471 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 78B8B601D3 for ; Thu, 26 Apr 2018 10:44:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 681992909D for ; Thu, 26 Apr 2018 10:44:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5D127290A8; Thu, 26 Apr 2018 10:44:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id BA2072909D for ; Thu, 26 Apr 2018 10:44:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=xnNaXO5D8olNfIyXFZbiOah6thG7dHq4B8vIc0cpst4=; b=ejf31tPScJbF+bCGPfT5jKjkGM L9zhM1Qzn8TC3UYdEV9OFSz2hBDKA8S1tv0K7lVWhicow6MtnvKGWJ6sSr65Y9M3i1Sr1/Q7zzgQ/ XLR7UXCb40mWYGIXnVHnHhYXagxlb1YbomZDjQGhQ/J/Bb+UTShwVVU9qXda1WjMK00zxsgQywQf7 72W8HTOGXRQPNA13zAnICjgJJ5fCeXRlbNSv6l6ztJo8L5Eh2+Z68/jfp+rg2pVojeI3uc5MEGTbs tY9lNs20wZF2Z8dQN0ZbsA2sswPcEwd4aGunukcNuiuRMgebYOo1MQS95QvNf2iJgcjWoEokOpmAg b/9FV19g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fBeNU-0008Om-1Z; Thu, 26 Apr 2018 10:43:52 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fBeET-00022a-0X for linux-arm-kernel@lists.infradead.org; Thu, 26 Apr 2018 10:34:35 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 770F51993; Thu, 26 Apr 2018 03:34:10 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 48F203F487; Thu, 26 Apr 2018 03:34:10 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 90BAE1AE5194; Thu, 26 Apr 2018 11:34:29 +0100 (BST) From: Will Deacon To: linux-kernel@vger.kernel.org Subject: [PATCH v3 10/14] locking/qspinlock: Make queued_spin_unlock use smp_store_release Date: Thu, 26 Apr 2018 11:34:24 +0100 Message-Id: <1524738868-31318-11-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1524738868-31318-1-git-send-email-will.deacon@arm.com> References: <1524738868-31318-1-git-send-email-will.deacon@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180426_033433_103073_941C93FE X-CRM114-Status: GOOD ( 14.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peterz@infradead.org, boqun.feng@gmail.com, will.deacon@arm.com, longman@redhat.com, paulmck@linux.vnet.ibm.com, mingo@kernel.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP A qspinlock can be unlocked simply by writing zero to the locked byte. This can be implemented in the generic code, so do that and remove the arch-specific override for x86 in the !PV case. Cc: Peter Zijlstra Cc: Ingo Molnar Signed-off-by: Will Deacon --- arch/x86/include/asm/qspinlock.h | 17 ++++++----------- include/asm-generic/qspinlock.h | 2 +- 2 files changed, 7 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h index da1370ad206d..3e70bed8a978 100644 --- a/arch/x86/include/asm/qspinlock.h +++ b/arch/x86/include/asm/qspinlock.h @@ -9,6 +9,12 @@ #define _Q_PENDING_LOOPS (1 << 9) +#ifdef CONFIG_PARAVIRT_SPINLOCKS +extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); +extern void __pv_init_lock_hash(void); +extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); +extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock); + #define queued_spin_unlock queued_spin_unlock /** * queued_spin_unlock - release a queued spinlock @@ -21,12 +27,6 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) smp_store_release(&lock->locked, 0); } -#ifdef CONFIG_PARAVIRT_SPINLOCKS -extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); -extern void __pv_init_lock_hash(void); -extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); -extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock); - static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) { pv_queued_spin_lock_slowpath(lock, val); @@ -42,11 +42,6 @@ static inline bool vcpu_is_preempted(long cpu) { return pv_vcpu_is_preempted(cpu); } -#else -static inline void queued_spin_unlock(struct qspinlock *lock) -{ - native_queued_spin_unlock(lock); -} #endif #ifdef CONFIG_PARAVIRT diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h index b37b4ad7eb94..a8ed0a352d75 100644 --- a/include/asm-generic/qspinlock.h +++ b/include/asm-generic/qspinlock.h @@ -100,7 +100,7 @@ static __always_inline void queued_spin_unlock(struct qspinlock *lock) /* * unlock() needs release semantics: */ - (void)atomic_sub_return_release(_Q_LOCKED_VAL, &lock->val); + smp_store_release(&lock->locked, 0); } #endif