From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH] x86, acpi, idle: Restructure the mwait idle routines Date: Tue, 19 Nov 2013 16:13:38 +0100 Message-ID: <20131119151338.GF3694@twins.programming.kicks-ass.net> References: <20131119090019.GJ3866@twins.programming.kicks-ass.net> <20131119090859.GC3694@twins.programming.kicks-ass.net> <20131119113153.GD3694@twins.programming.kicks-ass.net> <528B7433.7020507@linux.intel.com> <20131119145143.GK10022@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from merlin.infradead.org ([205.233.59.134]:40583 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301Ab3KSPNv (ORCPT ); Tue, 19 Nov 2013 10:13:51 -0500 Content-Disposition: inline In-Reply-To: <20131119145143.GK10022@twins.programming.kicks-ass.net> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Arjan van de Ven Cc: lenb@kernel.org, rjw@rjwysocki.net, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, shaohua.li@intel.com, rui.zhang@intel.com, jacob.jun.pan@linux.intel.com, Mike Galbraith , Ingo Molnar , Thomas Gleixner , hpa@zytor.com On Tue, Nov 19, 2013 at 03:51:43PM +0100, Peter Zijlstra wrote: > That said, that drive is completely wrecked. It uses > preempt_enable_no_resched() wrong too, it has uncommented barriers.. > > Dude, wtf are you guys smoking? --- Subject: sched: Take away preempt_enable_no_resched() and friends from modules There is no way in hell modules are going to play preemption tricks like this. Cc: eliezer.tamir@linux.intel.com Cc: arjan@linux.intel.com Reviewed-by: Thomas Gleixner Signed-off-by: Peter Zijlstra --- drivers/thermal/intel_powerclamp.c | 2 +- include/linux/preempt.h | 8 +++++++- include/net/busy_poll.h | 15 +++------------ 3 files changed, 11 insertions(+), 14 deletions(-) diff --git a/drivers/thermal/intel_powerclamp.c b/drivers/thermal/intel_powerclamp.c index 8f181b3f842b..0a12ddc2eb4c 100644 --- a/drivers/thermal/intel_powerclamp.c +++ b/drivers/thermal/intel_powerclamp.c @@ -445,7 +445,7 @@ static int clamp_thread(void *arg) atomic_inc(&idle_wakeup_counter); } tick_nohz_idle_exit(); - preempt_enable_no_resched(); + preempt_enable(); } del_timer_sync(&wakeup_timer); clear_bit(cpunr, cpu_clamping_mask); diff --git a/include/linux/preempt.h b/include/linux/preempt.h index a3d9dc8c2c00..3ed2b5335ab4 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -64,7 +64,7 @@ do { \ } while (0) #else -#define preempt_enable() preempt_enable_no_resched() +#define preempt_enable() sched_preempt_enable_no_resched() #define preempt_check_resched() do { } while (0) #endif @@ -116,6 +116,12 @@ do { \ #endif /* CONFIG_PREEMPT_COUNT */ +#ifdef MODULE +#undef preempt_enable_no_resched +#undef preempt_enable_no_resched_notrace +#undef preempt_check_resched +#endif + #ifdef CONFIG_PREEMPT_NOTIFIERS struct preempt_notifier; diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index 829627d7b846..756827a86c2d 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -42,27 +42,18 @@ static inline bool net_busy_loop_on(void) return sysctl_net_busy_poll; } -/* a wrapper to make debug_smp_processor_id() happy - * we can use sched_clock() because we don't care much about precision - * we only care that the average is bounded - */ -#ifdef CONFIG_DEBUG_PREEMPT static inline u64 busy_loop_us_clock(void) { u64 rc; + /* XXX with interrupts enabled sched_clock() can return utter garbage */ + preempt_disable_notrace(); rc = sched_clock(); - preempt_enable_no_resched_notrace(); + preempt_enable_notrace(); return rc >> 10; } -#else /* CONFIG_DEBUG_PREEMPT */ -static inline u64 busy_loop_us_clock(void) -{ - return sched_clock() >> 10; -} -#endif /* CONFIG_DEBUG_PREEMPT */ static inline unsigned long sk_busy_loop_end_time(struct sock *sk) {