From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752012Ab3LLOVc (ORCPT ); Thu, 12 Dec 2013 09:21:32 -0500 Received: from merlin.infradead.org ([205.233.59.134]:36068 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986Ab3LLOVU (ORCPT ); Thu, 12 Dec 2013 09:21:20 -0500 Message-Id: <20131212141655.059169830@infradead.org> User-Agent: quilt/0.60-1 Date: Thu, 12 Dec 2013 15:08:43 +0100 From: Peter Zijlstra To: Arjan van de Ven , lenb@kernel.org, rjw@rjwysocki.net, Eliezer Tamir , rui.zhang@intel.com, jacob.jun.pan@linux.intel.com, Mike Galbraith , Ingo Molnar , hpa@zytor.com, paulmck@linux.vnet.ibm.com, Thomas Gleixner , John Stultz , Andy Lutomirski , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Rusty Russell Subject: [PATCH 08/15] preempt: Take away preempt_enable_no_resched() from modules References: <20131212140835.729222186@infradead.org> Content-Disposition: inline; filename=peterz-hide-preempt_enable_no_resched-modules.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Discourage drivers/modules to be creative with preemption. Sadly all is implemented in macros and inline so if they want to do evil they still can, but at least try and discourage some. Cc: Eliezer Tamir Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith Cc: Ingo Molnar Cc: hpa@zytor.com Cc: Rusty Russell Cc: Arjan van de Ven Cc: lenb@kernel.org Cc: rjw@rjwysocki.net Reviewed-by: Thomas Gleixner Signed-off-by: Peter Zijlstra --- include/linux/preempt.h | 22 ++++++++++++++++++++-- include/linux/uaccess.h | 5 ++++- 2 files changed, 24 insertions(+), 3 deletions(-) --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -64,7 +64,11 @@ do { \ } while (0) #else -#define preempt_enable() preempt_enable_no_resched() +#define preempt_enable() \ +do { \ + barrier(); \ + preempt_count_dec(); \ +} while (0) #define preempt_check_resched() do { } while (0) #endif @@ -93,7 +97,11 @@ do { \ __preempt_schedule_context(); \ } while (0) #else -#define preempt_enable_notrace() preempt_enable_no_resched_notrace() +#define preempt_enable_notrace() \ +do { \ + barrier(); \ + __preempt_count_dec(); \ +} while (0) #endif #else /* !CONFIG_PREEMPT_COUNT */ @@ -126,6 +134,16 @@ do { \ #define preempt_fold_need_resched() do { } while (0) #endif +#ifdef MODULE +/* + * Modules have no business playing preemption tricks. + */ +#undef sched_preempt_enable_no_resched +#undef preempt_enable_no_resched +#undef preempt_enable_no_resched_notrace +#undef preempt_check_resched +#endif + #ifdef CONFIG_PREEMPT_NOTIFIERS struct preempt_notifier; --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -25,13 +25,16 @@ static inline void pagefault_disable(voi static inline void pagefault_enable(void) { +#ifndef CONFIG_PREEMPT /* * make sure to issue those last loads/stores before enabling * the pagefault handler again. */ barrier(); preempt_count_dec(); - preempt_check_resched(); +#else + preempt_enable(); +#endif } #ifndef ARCH_HAS_NOCACHE_UACCESS