From patchwork Thu Oct 12 12:20:47 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 115612 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp1875367qgn; Thu, 12 Oct 2017 05:21:10 -0700 (PDT) X-Google-Smtp-Source: AOwi7QAv4Q/0BXwvFW2sw+RwdualHcYH/3GWWosaIwU8k/ghJAtTx+ehkJuHdPFkIYYujJeSRB74 X-Received: by 10.99.164.81 with SMTP id c17mr70041pgp.445.1507810869901; Thu, 12 Oct 2017 05:21:09 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507810869; cv=none; d=google.com; s=arc-20160816; b=cWtTv8zhL0d4e9ivj7e0sPZnva+DHnGkFXD+s+OrCeaaY/3P94yTXN+sfg0kbd27my 4HCVhr5/KhQd9rN9n5iiLdS+U9PbGb7Z2ELDcyhxRpLvw5xGApU3XZsb901v9cmjAV2r tPawjIfHVyvmNpiLMC3DAInbKb/XNBPXPM94qx3aMplg0hqs7XxSjna1q9gRgZfmDt4m R/7tkozPIsWK77Z4KIX1Mwu7TB5UwQkmedV3+8Cv3XTmfmU+wRpGdLpSmT5gfshgGQmd AjVcxIwVdm15JFnco4hBk0h6WF0Tr2Jo1GO7SZp9MTt2V9atcjWnnmCNpVNiakMtOzHn PIhw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=w7TWWYNyuCNcNGH1mif+F9tnZIJtaXKDG3iGHaIC/Rg=; b=Kent5uaoLXR0ff7mRrfeiSMOSD2dU1fTULzszAs8woSwcDF6xCw1Gll+XYY0pTm/tX +2DXOXbqUoXWiBlYVOL6J42Q+HHeiObXvdBhy4pCaPNArZD2G8f8o3L6Sy9QiOXp1782 bxK68xUY0J25jDVOytmx+ixiiH+bd8IUPsqrce08V00sV35QrEJdO5HLoEoYETcgPNW5 k8faPVnokDgNFqyhjylsWw/CpHMmvISKpCVMPO7Uu8gDPQHJLy33BQ57lhsVsm0Rb+rp oIW7ght7G4f6ABcQpvMLPU4vUFl2wCJuIfrNarxNtToHAQ2HTJQVz9BvPs9ugO54cuMl hhXg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id r145si6892595pgr.753.2017.10.12.05.21.09; Thu, 12 Oct 2017 05:21:09 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757419AbdJLMUz (ORCPT + 27 others); Thu, 12 Oct 2017 08:20:55 -0400 Received: from foss.arm.com ([217.140.101.70]:45514 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757008AbdJLMUt (ORCPT ); Thu, 12 Oct 2017 08:20:49 -0400 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 9647A15BE; Thu, 12 Oct 2017 05:20:48 -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 682DB3F59C; Thu, 12 Oct 2017 05:20:48 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 184241AE1952; Thu, 12 Oct 2017 13:20:52 +0100 (BST) From: Will Deacon To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Jeremy.Linton@arm.com, peterz@infradead.org, mingo@redhat.com, longman@redhat.com, boqun.feng@gmail.com, paulmck@linux.vnet.ibm.com, Will Deacon Subject: [PATCH v3 1/5] kernel/locking: Use struct qrwlock instead of struct __qrwlock Date: Thu, 12 Oct 2017 13:20:47 +0100 Message-Id: <1507810851-306-2-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1507810851-306-1-git-send-email-will.deacon@arm.com> References: <1507810851-306-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There's no good reason to keep the internal structure of struct qrwlock hidden from qrwlock.h, particularly as it's actually needed for unlock and ends up being abstracted independently behind the __qrwlock_write_byte function. Stop pretending we can hide this stuff, and move the __qrwlock definition into qrwlock, removing the __qrwlock_write_byte nastiness and using the same struct definition everywhere instead. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Waiman Long Cc: Boqun Feng Cc: "Paul E. McKenney" Signed-off-by: Will Deacon --- include/asm-generic/qrwlock.h | 12 +----------- include/asm-generic/qrwlock_types.h | 15 +++++++++++++-- kernel/locking/qrwlock.c | 26 ++------------------------ 3 files changed, 16 insertions(+), 37 deletions(-) -- 2.1.4 diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index 50925327b0a8..02c0a768e6b0 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -129,22 +129,12 @@ static inline void queued_read_unlock(struct qrwlock *lock) } /** - * __qrwlock_write_byte - retrieve the write byte address of a queue rwlock - * @lock : Pointer to queue rwlock structure - * Return: the write byte address of a queue rwlock - */ -static inline u8 *__qrwlock_write_byte(struct qrwlock *lock) -{ - return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN); -} - -/** * queued_write_unlock - release write lock of a queue rwlock * @lock : Pointer to queue rwlock structure */ static inline void queued_write_unlock(struct qrwlock *lock) { - smp_store_release(__qrwlock_write_byte(lock), 0); + smp_store_release(&lock->wmode, 0); } /* diff --git a/include/asm-generic/qrwlock_types.h b/include/asm-generic/qrwlock_types.h index 0abc6b6062fb..507f2dc51bba 100644 --- a/include/asm-generic/qrwlock_types.h +++ b/include/asm-generic/qrwlock_types.h @@ -9,12 +9,23 @@ */ typedef struct qrwlock { - atomic_t cnts; + union { + atomic_t cnts; + struct { +#ifdef __LITTLE_ENDIAN + u8 wmode; /* Writer mode */ + u8 rcnts[3]; /* Reader counts */ +#else + u8 rcnts[3]; /* Reader counts */ + u8 wmode; /* Writer mode */ +#endif + }; + }; arch_spinlock_t wait_lock; } arch_rwlock_t; #define __ARCH_RW_LOCK_UNLOCKED { \ - .cnts = ATOMIC_INIT(0), \ + { .cnts = ATOMIC_INIT(0), }, \ .wait_lock = __ARCH_SPIN_LOCK_UNLOCKED, \ } diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index 2655f26ec882..1af791e37348 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -23,26 +23,6 @@ #include #include -/* - * This internal data structure is used for optimizing access to some of - * the subfields within the atomic_t cnts. - */ -struct __qrwlock { - union { - atomic_t cnts; - struct { -#ifdef __LITTLE_ENDIAN - u8 wmode; /* Writer mode */ - u8 rcnts[3]; /* Reader counts */ -#else - u8 rcnts[3]; /* Reader counts */ - u8 wmode; /* Writer mode */ -#endif - }; - }; - arch_spinlock_t lock; -}; - /** * rspin_until_writer_unlock - inc reader count & spin until writer is gone * @lock : Pointer to queue rwlock structure @@ -125,10 +105,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock) * or wait for a previous writer to go away. */ for (;;) { - struct __qrwlock *l = (struct __qrwlock *)lock; - - if (!READ_ONCE(l->wmode) && - (cmpxchg_relaxed(&l->wmode, 0, _QW_WAITING) == 0)) + if (!READ_ONCE(lock->wmode) && + (cmpxchg_relaxed(&lock->wmode, 0, _QW_WAITING) == 0)) break; cpu_relax();