From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp07.au.ibm.com (e23smtp07.au.ibm.com [202.81.31.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp07.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 00F92B6F77 for ; Mon, 21 May 2012 14:59:06 +1000 (EST) Received: from /spool/local by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 21 May 2012 04:51:04 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q4L4uMij45220064 for ; Mon, 21 May 2012 14:58:58 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q4L4tAVE012012 for ; Mon, 21 May 2012 14:55:11 +1000 Message-ID: <4FB9CAAB.9050807@linux.vnet.ibm.com> Date: Mon, 21 May 2012 10:25:07 +0530 From: Deepthi Dharwar MIME-Version: 1.0 To: Benjamin Herrenschmidt Subject: Re: [PATCH] cpuidle: (POWER) Replace pseries_notify_cpuidle_add call with a elegant notifier to fix lockdep problem in start_secondary References: <4FB64E9A.3060100@linux.vnet.ibm.com> <1337561221.2458.1.camel@pasglop> In-Reply-To: <1337561221.2458.1.camel@pasglop> Content-Type: text/plain; charset=ISO-8859-1 Cc: Paul Mackerras , "Paul E. McKenney" , PowerPC email list , "linux-kernel@vger.kernel.org" , Li Zhong List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Ben, On 05/21/2012 06:17 AM, Benjamin Herrenschmidt wrote: > On Fri, 2012-05-18 at 18:58 +0530, Deepthi Dharwar wrote: >> The following patch is to remove the pseries_notify_add_cpu() call >> and replace it by a hot plug notifier. >> This would prevent cpuidle resources being >> released and allocated each time cpu comes online on pseries. >> The earlier design was causing a lockdep problem >> in start_secondary as reported on this thread >> -https://lkml.org/lkml/2012/5/17/2 >> >> This applies on 3.4-rc7 >> >> Signed-off-by: Deepthi Dharwar >> --- > > Any reason why you don't do cpuidle_disable_device() when the > CPU is going offline and cpuidle_enable_device() when it's coming > back ? In the current design disable and enable device are called when the cpu comes online. This is to make sure that we clean up and re-register again. All the counters are reset. Not calling cpu disable when cpu goes offline currently, would only retain the counters right now. But I could add a offline check and disable the device there, if that results in cleaner design. I will test and send across the patch with couple more pseries-idle fixes soon. Thanks for your review comments ! > I'm applying the patch for now since it fixes a real problem but > if the above makes sense, please send a followup fix. > > Cheers, > Ben. > >> arch/powerpc/include/asm/processor.h | 2 -- >> arch/powerpc/platforms/pseries/processor_idle.c | 25 >> +++++++++++++++++------ >> arch/powerpc/platforms/pseries/smp.c | 1 - >> 3 files changed, 19 insertions(+), 9 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/processor.h >> b/arch/powerpc/include/asm/processor.h >> index 8e2d037..c6bc22b 100644 >> --- a/arch/powerpc/include/asm/processor.h >> +++ b/arch/powerpc/include/asm/processor.h >> @@ -390,10 +390,8 @@ void cpu_idle_wait(void); >> >> #ifdef CONFIG_PSERIES_IDLE >> extern void update_smt_snooze_delay(int snooze); >> -extern int pseries_notify_cpuidle_add_cpu(int cpu); >> #else >> static inline void update_smt_snooze_delay(int snooze) {} >> -static inline int pseries_notify_cpuidle_add_cpu(int cpu) { return 0; } >> #endif >> >> extern void flush_instruction_cache(void); >> diff --git a/arch/powerpc/platforms/pseries/processor_idle.c >> b/arch/powerpc/platforms/pseries/processor_idle.c >> index 41a34bc..d1a7dc0 100644 >> --- a/arch/powerpc/platforms/pseries/processor_idle.c >> +++ b/arch/powerpc/platforms/pseries/processor_idle.c >> @@ -11,6 +11,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -186,17 +187,28 @@ static struct cpuidle_state >> shared_states[MAX_IDLE_STATE_COUNT] = { >> .enter = &shared_cede_loop }, >> }; >> >> -int pseries_notify_cpuidle_add_cpu(int cpu) >> +static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n, >> + unsigned long action, void *hcpu) >> { >> + int hotcpu = (unsigned long)hcpu; >> struct cpuidle_device *dev = >> - per_cpu_ptr(pseries_cpuidle_devices, cpu); >> - if (dev && cpuidle_get_driver()) { >> - cpuidle_disable_device(dev); >> - cpuidle_enable_device(dev); >> + per_cpu_ptr(pseries_cpuidle_devices, hotcpu); >> + >> + switch (action & 0xf) { >> + case CPU_ONLINE: >> + if (dev && cpuidle_get_driver()) { >> + cpuidle_disable_device(dev); >> + cpuidle_enable_device(dev); >> + } >> + break; >> } >> - return 0; >> + return NOTIFY_OK; >> } >> >> +static struct notifier_block setup_hotplug_notifier = { >> + .notifier_call = pseries_cpuidle_add_cpu_notifier, >> +}; >> + >> /* >> * pseries_cpuidle_driver_init() >> */ >> @@ -321,6 +333,7 @@ static int __init pseries_processor_idle_init(void) >> return retval; >> } >> >> + register_cpu_notifier(&setup_hotplug_notifier); >> printk(KERN_DEBUG "pseries_idle_driver registered\n"); >> >> return 0; >> diff --git a/arch/powerpc/platforms/pseries/smp.c >> b/arch/powerpc/platforms/pseries/smp.c >> index e16bb8d..71706bc 100644 >> --- a/arch/powerpc/platforms/pseries/smp.c >> +++ b/arch/powerpc/platforms/pseries/smp.c >> @@ -147,7 +147,6 @@ static void __devinit smp_xics_setup_cpu(int cpu) >> set_cpu_current_state(cpu, CPU_STATE_ONLINE); >> set_default_offline_state(cpu); >> #endif >> - pseries_notify_cpuidle_add_cpu(cpu); >> } >> >> static int __devinit smp_pSeries_kick_cpu(int nr) > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >