From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] sched, cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE Date: Wed, 01 Jun 2016 22:20:03 +0200 Message-ID: <4245615.v9qo6igreM@vostro.rjw.lan> References: <1464803536-19929-1-git-send-email-catalin.marinas@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from cloudserver094114.home.net.pl ([79.96.170.134]:56145 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750807AbcFAUQM (ORCPT ); Wed, 1 Jun 2016 16:16:12 -0400 In-Reply-To: <1464803536-19929-1-git-send-email-catalin.marinas@arm.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Catalin Marinas Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Lezcano , Ingo Molnar , Peter Zijlstra , Andrey Ryabinin On Wednesday, June 01, 2016 06:52:16 PM Catalin Marinas wrote: > 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 OK Is this needed in -stable? > --- > > 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; >