Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754706AbbHCRDh (ORCPT ); Mon, 3 Aug 2015 13:03:37 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:62366 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754637AbbHCRDb (ORCPT ); Mon, 3 Aug 2015 13:03:31 -0400 From: Will Deacon To: linux-arch@vger.kernel.org Cc: Waiman.Long@hp.com, peterz@infradead.org, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, mingo@kernel.org, Will Deacon Subject: [PATCH v4 5/8] locking/qrwlock: implement queue_write_unlock using smp_store_release Date: Mon, 3 Aug 2015 18:02:28 +0100 Message-Id: <1438621351-15912-6-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1438621351-15912-1-git-send-email-will.deacon@arm.com> References: <1438621351-15912-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2103 Lines: 66 Since 536fa402221f ("compiler: Allow 1- and 2-byte smp_load_acquire() and smp_store_release()"), smp_store_release supports byte accesses, so use that in writer unlock and remove the conditional macro override. Signed-off-by: Will Deacon --- arch/x86/include/asm/qrwlock.h | 10 ---------- include/asm-generic/qrwlock.h | 9 +-------- 2 files changed, 1 insertion(+), 18 deletions(-) diff --git a/arch/x86/include/asm/qrwlock.h b/arch/x86/include/asm/qrwlock.h index a8810bf135ab..c537cbb038a7 100644 --- a/arch/x86/include/asm/qrwlock.h +++ b/arch/x86/include/asm/qrwlock.h @@ -2,16 +2,6 @@ #define _ASM_X86_QRWLOCK_H #include - -#ifndef CONFIG_X86_PPRO_FENCE -#define queued_write_unlock queued_write_unlock -static inline void queued_write_unlock(struct qrwlock *lock) -{ - barrier(); - ACCESS_ONCE(*(u8 *)&lock->cnts) = 0; -} -#endif - #include #endif /* _ASM_X86_QRWLOCK_H */ diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index deb9e8b0eb9e..eb673dde8879 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -134,21 +134,14 @@ static inline void queued_read_unlock(struct qrwlock *lock) atomic_sub(_QR_BIAS, &lock->cnts); } -#ifndef queued_write_unlock /** * 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) { - /* - * If the writer field is atomic, it can be cleared directly. - * Otherwise, an atomic subtraction will be used to clear it. - */ - smp_mb__before_atomic(); - atomic_sub(_QW_LOCKED, &lock->cnts); + smp_store_release((u8 *)&lock->cnts, 0); } -#endif /* * Remapping rwlock architecture specific functions to the corresponding -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/