From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753025AbcEMOTH (ORCPT ); Fri, 13 May 2016 10:19:07 -0400 Received: from terminus.zytor.com ([198.137.202.10]:44808 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751693AbcEMOTF (ORCPT ); Fri, 13 May 2016 10:19:05 -0400 Date: Fri, 13 May 2016 07:15:39 -0700 From: tip-bot for Steven Rostedt Message-ID: Cc: torvalds@linux-foundation.org, eranian@google.com, acme@redhat.com, tglx@linutronix.de, alexander.shishkin@linux.intel.com, bp@suse.de, ard.biesheuvel@linaro.org, rostedt@goodmis.org, hpa@zytor.com, mingo@kernel.org, jolsa@redhat.com, arnd@arndb.de, linux@roeck-us.net, luto@kernel.org, linux@armlinux.org.uk, vincent.weaver@maine.edu, rmk+kernel@arm.linux.org.uk, fweisbec@gmail.com, luto@amacapital.net, mgorman@techsingularity.net, linux-kernel@vger.kernel.org, peterz@infradead.org Reply-To: peterz@infradead.org, mgorman@techsingularity.net, linux-kernel@vger.kernel.org, luto@amacapital.net, vincent.weaver@maine.edu, linux@armlinux.org.uk, fweisbec@gmail.com, rmk+kernel@arm.linux.org.uk, arnd@arndb.de, linux@roeck-us.net, luto@kernel.org, mingo@kernel.org, jolsa@redhat.com, rostedt@goodmis.org, ard.biesheuvel@linaro.org, hpa@zytor.com, tglx@linutronix.de, alexander.shishkin@linux.intel.com, bp@suse.de, acme@redhat.com, eranian@google.com, torvalds@linux-foundation.org In-Reply-To: <1463146234-161304-1-git-send-email-arnd@arndb.de> References: <1463146234-161304-1-git-send-email-arnd@arndb.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] ARM: Hide finish_arch_post_lock_switch() from modules Git-Commit-ID: ef0491ea17f8019821c7e9c8e801184ecf17f85a X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ef0491ea17f8019821c7e9c8e801184ecf17f85a Gitweb: http://git.kernel.org/tip/ef0491ea17f8019821c7e9c8e801184ecf17f85a Author: Steven Rostedt AuthorDate: Fri, 13 May 2016 15:30:13 +0200 Committer: Ingo Molnar CommitDate: Fri, 13 May 2016 16:12:53 +0200 ARM: Hide finish_arch_post_lock_switch() from modules The introduction of switch_mm_irqs_off() brought back an old bug regarding the use of preempt_enable_no_resched: As part of: 62b94a08da1b ("sched/preempt: Take away preempt_enable_no_resched() from modules") the definition of preempt_enable_no_resched() is only available in built-in code, not in loadable modules, so we can't generally use it from header files. However, the ARM version of finish_arch_post_lock_switch() calls preempt_enable_no_resched() and is defined as a static inline function in asm/mmu_context.h. This in turn means we cannot include asm/mmu_context.h from modules. With today's tip tree, asm/mmu_context.h gets included from linux/mmu_context.h, which is normally the exact pattern one would expect, but unfortunately, linux/mmu_context.h can be included from the vhost driver that is a loadable module, now causing this compile time error with modular configs: In file included from ../include/linux/mmu_context.h:4:0, from ../drivers/vhost/vhost.c:18: ../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch': ../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration] preempt_enable_no_resched(); Andy already tried to fix the bug by including linux/preempt.h from asm/mmu_context.h, but that didn't help. Arnd suggested reordering the header files, which wasn't popular, so let's use this workaround instead: The finish_arch_post_lock_switch() definition is now also hidden inside of #ifdef MODULE, so we don't see anything referencing preempt_enable_no_resched() from a header file. I've built a few hundred randconfig kernels with this, and did not see any new problems. Tested-by: Guenter Roeck Signed-off-by: Steven Rostedt Signed-off-by: Arnd Bergmann Acked-by: Russell King Cc: Alexander Shishkin Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mel Gorman Cc: Peter Zijlstra Cc: Russell King - ARM Linux Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: linux-arm-kernel@lists.infradead.org Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler") Link: http://lkml.kernel.org/r/1463146234-161304-1-git-send-email-arnd@arndb.de Signed-off-by: Ingo Molnar --- arch/arm/include/asm/mmu_context.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h index ed73bab..3cc14dd 100644 --- a/arch/arm/include/asm/mmu_context.h +++ b/arch/arm/include/asm/mmu_context.h @@ -67,6 +67,7 @@ static inline void check_and_switch_context(struct mm_struct *mm, cpu_switch_mm(mm->pgd, mm); } +#ifndef MODULE #define finish_arch_post_lock_switch \ finish_arch_post_lock_switch static inline void finish_arch_post_lock_switch(void) @@ -88,6 +89,7 @@ static inline void finish_arch_post_lock_switch(void) preempt_enable_no_resched(); } } +#endif /* !MODULE */ #endif /* CONFIG_MMU */