Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755426Ab3I3OHG (ORCPT ); Mon, 30 Sep 2013 10:07:06 -0400 Received: from mail-wi0-f173.google.com ([209.85.212.173]:38619 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755167Ab3I3OHC (ORCPT ); Mon, 30 Sep 2013 10:07:02 -0400 From: Frederic Weisbecker To: Kevin Hilman Cc: LKML , Ingo Molnar , Russell King , "Paul E. McKenney" , Arm Linux , Frederic Weisbecker Subject: [PATCH 1/3] vtime: Add HAVE_VIRT_CPU_ACCOUNTING_GEN Kconfig Date: Mon, 30 Sep 2013 16:06:50 +0200 Message-Id: <1380550012-7321-2-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1380550012-7321-1-git-send-email-fweisbec@gmail.com> References: <1380550012-7321-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2777 Lines: 83 From: Kevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. In order to use that feature, arch code should be audited to ensure there are no races in concurrent read/write of cputime_t. For example, reading/writing 64-bit cputime_t on some 32-bit arches may require multiple accesses for low and high value parts, so proper locking is needed to protect against concurrent accesses. Therefore, add CONFIG_HAVE_VIRT_CPU_ACCOUNTING_GEN which arches can enable after they've been audited for potential races. This option is automatically enabled on 64-bit platforms. Feature requested by Frederic Weisbecker. Signed-off-by: Kevin Hilman Cc: Ingo Molnar Cc: Russell King Cc: Paul E. McKenney Cc: Arm Linux Signed-off-by: Frederic Weisbecker --- arch/Kconfig | 12 ++++++++++++ init/Kconfig | 1 + kernel/time/Kconfig | 1 + 3 files changed, 14 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index af2cc6e..185f8b0 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -353,6 +353,18 @@ config HAVE_CONTEXT_TRACKING config HAVE_VIRT_CPU_ACCOUNTING bool +config HAVE_VIRT_CPU_ACCOUNTING_GEN + bool + default y if 64BIT + help + With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. + Before enabling this option, arch code must be audited + to ensure there are no races in concurrent read/write of + cputime_t. For example, reading/writing 64-bit cputime_t on + some 32-bit arches may require multiple accesses, so proper + locking is needed to protect against concurrent accesses. + + config HAVE_IRQ_TIME_ACCOUNTING bool help diff --git a/init/Kconfig b/init/Kconfig index 3ecd8a1..68c1a0e 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -355,6 +355,7 @@ config VIRT_CPU_ACCOUNTING_NATIVE config VIRT_CPU_ACCOUNTING_GEN bool "Full dynticks CPU time accounting" depends on HAVE_CONTEXT_TRACKING && 64BIT + depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select VIRT_CPU_ACCOUNTING select CONTEXT_TRACKING help diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 2b62fe8..f148475 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -101,6 +101,7 @@ config NO_HZ_FULL depends on HAVE_CONTEXT_TRACKING # VIRT_CPU_ACCOUNTING_GEN dependency depends on 64BIT + depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON select RCU_USER_QS select RCU_NOCB_CPU -- 1.8.3.1 -- 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/