Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752046Ab2F0NGm (ORCPT ); Wed, 27 Jun 2012 09:06:42 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56873 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750775Ab2F0NGk (ORCPT ); Wed, 27 Jun 2012 09:06:40 -0400 From: Thomas Renninger Organization: SUSE Products GmbH To: Daniel Lezcano Subject: Re: [PATCH] acpi: intel_idle : break dependency between modules Date: Wed, 27 Jun 2012 15:06:28 +0200 User-Agent: KMail/1.13.6 (Linux/2.6.37.6-0.11-desktop; KDE/4.6.0; x86_64; ; ) Cc: srivatsa.bhat@linux.vnet.ibm.com, deepthi@linux.vnet.ibm.com, linux-acpi@vger.kernel.org, linux-pm@lists.linux-foundation.org, linux-pm@vger.kernel.org, lenb@kernel.org, rjw@sisk.pl, x86@kernel.org, linux-kernel@vger.kernel.org, linaro-dev@lists.linaro.org References: <201206261301.25550.trenn@suse.de> <1340788068-16422-1-git-send-email-daniel.lezcano@linaro.org> In-Reply-To: <1340788068-16422-1-git-send-email-daniel.lezcano@linaro.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-6" Content-Transfer-Encoding: 7bit Message-Id: <201206271506.29034.trenn@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5949 Lines: 164 Hi, I agree that such a dependency between 2 modules is not nice. But your patch will have bad side-effects (see comments embedded below). On Wednesday, June 27, 2012 11:07:48 AM Daniel Lezcano wrote: > When the system is booted with some cpus offline, the idle > driver is not initialized. When a cpu is set online, the > acpi code call the intel idle init function. Unfortunately > this code introduce a dependency between intel_idle and acpi. > > This patch is intended to remove this dependency by using the > notifier of intel_idle. In order to make it work, the notifier > must be initialized in the right order, acpi then intel_idle. > This is done in the Makefile. This patch has the benefit of > encapsulating the intel_idle driver and remove some exported > functions. > > Signed-off-by: Daniel Lezcano > --- > drivers/Makefile | 3 ++- > drivers/acpi/processor_driver.c | 7 ------- > drivers/idle/intel_idle.c | 22 ++++++++++++++-------- > include/linux/cpuidle.h | 7 ------- > 4 files changed, 16 insertions(+), 23 deletions(-) > > diff --git a/drivers/Makefile b/drivers/Makefile > index 2ba29ff..a2454b8 100644 > --- a/drivers/Makefile > +++ b/drivers/Makefile > @@ -12,8 +12,9 @@ obj-$(CONFIG_PCI) += pci/ > obj-$(CONFIG_PARISC) += parisc/ > obj-$(CONFIG_RAPIDIO) += rapidio/ > obj-y += video/ > -obj-y += idle/ > +# acpi must come before idle for initialization > obj-$(CONFIG_ACPI) += acpi/ > +obj-y += idle/ This breaks intel_idle. Loading order defines which one comes first and is used: intel_idle or ACPI processor cpuidle driver. With above, one would get acpi_idle cpuidle driver if both are compiled in, instead of the intel_idle one. Why exactly is this necessary, couldn't it just work? > obj-$(CONFIG_SFI) += sfi/ > # PnP must come after ACPI since it will eventually need to check if acpi > # was used and do nothing if so > diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c > index 0734086..8648b29 100644 > --- a/drivers/acpi/processor_driver.c > +++ b/drivers/acpi/processor_driver.c > @@ -427,18 +427,11 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb, > * Initialize missing things > */ > if (pr->flags.need_hotplug_init) { > - struct cpuidle_driver *idle_driver = > - cpuidle_get_driver(); > - > printk(KERN_INFO "Will online and init hotplugged " > "CPU: %d\n", pr->id); > WARN(acpi_processor_start(pr), "Failed to start CPU:" > " %d\n", pr->id); > pr->flags.need_hotplug_init = 0; > - if (idle_driver && !strcmp(idle_driver->name, > - "intel_idle")) { > - intel_idle_cpu_init(pr->id); > - } > /* Normal CPU soft online event */ > } else { > acpi_processor_ppc_has_changed(pr, 0); > diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c > index d0f59c3..4c36039 100644 > --- a/drivers/idle/intel_idle.c > +++ b/drivers/idle/intel_idle.c > @@ -96,6 +96,7 @@ static const struct idle_cpu *icpu; > static struct cpuidle_device __percpu *intel_idle_cpuidle_devices; > static int intel_idle(struct cpuidle_device *dev, > struct cpuidle_driver *drv, int index); > +static int intel_idle_cpu_init(int cpu); > > static struct cpuidle_state *cpuidle_state_table; > > @@ -302,22 +303,28 @@ static void __setup_broadcast_timer(void *arg) > clockevents_notify(reason, &cpu); > } > > -static int setup_broadcast_cpuhp_notify(struct notifier_block *n, > - unsigned long action, void *hcpu) > +static int cpu_hotplug_notify(struct notifier_block *n, > + unsigned long action, void *hcpu) > { > int hotcpu = (unsigned long)hcpu; > + struct cpuidle_device *dev; > > switch (action & 0xf) { > case CPU_ONLINE: > smp_call_function_single(hotcpu, __setup_broadcast_timer, > (void *)true, 1); > + > + dev = per_cpu_ptr(intel_idle_cpuidle_devices, hotcpu); > + if (!dev->registered) > + intel_idle_cpu_init(hotcpu); > + A small comment why this can happen and needs to be done (real hotplugged cpu case) might help here later. > break; > } > return NOTIFY_OK; > } > > -static struct notifier_block setup_broadcast_notifier = { > - .notifier_call = setup_broadcast_cpuhp_notify, > +static struct notifier_block cpu_hotplug_notifier = { > + .notifier_call = cpu_hotplug_notify, > }; > > static void auto_demotion_disable(void *dummy) > @@ -407,7 +414,7 @@ static int intel_idle_probe(void) > lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE; > else { > on_each_cpu(__setup_broadcast_timer, (void *)true, 1); > - register_cpu_notifier(&setup_broadcast_notifier); > + register_cpu_notifier(&cpu_hotplug_notifier); The notifier always has to be registered now, not only in: if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */ case. > } > > pr_debug(PREFIX "v" INTEL_IDLE_VERSION > @@ -494,7 +501,7 @@ static int intel_idle_cpuidle_driver_init(void) > * allocate, initialize, register cpuidle_devices > * @cpu: cpu/core to initialize > */ > -int intel_idle_cpu_init(int cpu) > +static int intel_idle_cpu_init(int cpu) > { > int cstate; > struct cpuidle_device *dev; > @@ -539,7 +546,6 @@ int intel_idle_cpu_init(int cpu) > > return 0; > } > -EXPORT_SYMBOL_GPL(intel_idle_cpu_init); > > static int __init intel_idle_init(void) > { > @@ -583,7 +589,7 @@ static void __exit intel_idle_exit(void) > > if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) { > on_each_cpu(__setup_broadcast_timer, (void *)false, 1); > - unregister_cpu_notifier(&setup_broadcast_notifier); > + unregister_cpu_notifier(&cpu_hotplug_notifier); Same. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/