From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: [PATCH] sched, cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE Date: Wed, 1 Jun 2016 18:52:16 +0100 Message-ID: <1464803536-19929-1-git-send-email-catalin.marinas@arm.com> Return-path: Received: from foss.arm.com ([217.140.101.70]:39330 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751130AbcFARwX (ORCPT ); Wed, 1 Jun 2016 13:52:23 -0400 Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Daniel Lezcano , Ingo Molnar , Peter Zijlstra , Andrey Ryabinin The cpuidle_devices per-CPU variable is only defined when CPU_IDLE is enabled. Commit c8cc7d4de7a4 ("sched/idle: Reorganize the idle loop") removed the #ifdef CONFIG_CPU_IDLE around cpuidle_idle_call() with the compiler optimising away __this_cpu_read(cpuidle_devices). However, with CONFIG_UBSAN && !CONFIG_CPU_IDLE, this optimisation no longer happens and the kernel fails to link since cpuidle_devices is not defined. This patch introduces an accessor function for the current CPU cpuidle device (returning NULL when !CONFIG_CPU_IDLE) and uses it in cpuidle_idle_call(). Cc: Rafael J. Wysocki Cc: Daniel Lezcano Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Andrey Ryabinin Signed-off-by: Catalin Marinas --- This fixes a build failure on arm64 with UBSAN && !CPU_IDLE and gcc 5.3.1 (probably other compiler versions would behave in the same way). I tried to keep close to the existing coding style in cpuidle.h. include/linux/cpuidle.h | 3 +++ kernel/sched/idle.c | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 786ad32631a6..07b83d32f66c 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -152,6 +152,8 @@ extern void cpuidle_disable_device(struct cpuidle_device *dev); extern int cpuidle_play_dead(void); extern struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev); +static inline struct cpuidle_device *cpuidle_get_device(void) +{return __this_cpu_read(cpuidle_devices); } #else static inline void disable_cpuidle(void) { } static inline bool cpuidle_not_available(struct cpuidle_driver *drv, @@ -187,6 +189,7 @@ static inline void cpuidle_disable_device(struct cpuidle_device *dev) { } static inline int cpuidle_play_dead(void) {return -ENODEV; } static inline struct cpuidle_driver *cpuidle_get_cpu_driver( struct cpuidle_device *dev) {return NULL; } +static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; } #endif #if defined(CONFIG_CPU_IDLE) && defined(CONFIG_SUSPEND) diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index bd12c6c714ec..c5aeedf4e93a 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -127,7 +127,7 @@ static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev, */ static void cpuidle_idle_call(void) { - struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); + struct cpuidle_device *dev = cpuidle_get_device(); struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); int next_state, entered_state;