From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932375AbcE0GRV (ORCPT ); Fri, 27 May 2016 02:17:21 -0400 Received: from mail-pa0-f67.google.com ([209.85.220.67]:35562 "EHLO mail-pa0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932285AbcE0GRR (ORCPT ); Fri, 27 May 2016 02:17:17 -0400 From: Minfei Huang To: bp@suse.de, pbonzini@redhat.com, luto@kernel.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Minfei Huang Subject: [PATCH 3/3] pvclock: Add a new wrapper function to only get variable flags Date: Fri, 27 May 2016 14:17:12 +0800 Message-Id: <1464329832-4638-3-git-send-email-mnghuan@gmail.com> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1464329832-4638-1-git-send-email-mnghuan@gmail.com> References: <1464329832-4638-1-git-send-email-mnghuan@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a generic function __pvclock_read_cycles to be used to get both flags and cycles. For function pvclock_read_flags, it's useless to get cycles value. To make this function be more effective, add a new wrapper function to only get variable flags. Signed-off-by: Minfei Huang --- arch/x86/include/asm/pvclock.h | 12 ++++++++++++ arch/x86/kernel/pvclock.c | 3 +-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index 7c1c895..3c4e5b7 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -88,6 +88,18 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, return version; } +static __always_inline unsigned int __pvclock_read_flags( + const struct pvclock_vcpu_time_info *src, u8 *flags) +{ + unsigned int version; + + version = src->version; + /* Make the latest version visible */ + smp_rmb(); + *flags = src->flags; + return version; +} + struct pvclock_vsyscall_time_info { struct pvclock_vcpu_time_info pvti; } __attribute__((__aligned__(SMP_CACHE_BYTES))); diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 7f82fe0..138772c 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -61,11 +61,10 @@ void pvclock_resume(void) u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src) { unsigned version; - cycle_t ret; u8 flags; do { - version = __pvclock_read_cycles(src, &ret, &flags); + version = __pvclock_read_flags(src, &flags); /* Make sure that the version double-check is last. */ smp_rmb(); } while ((src->version & 1) || version != src->version); -- 2.6.3