From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932586AbWG1IQM (ORCPT ); Fri, 28 Jul 2006 04:16:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932591AbWG1IQM (ORCPT ); Fri, 28 Jul 2006 04:16:12 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:31970 "EHLO ogre.sisk.pl") by vger.kernel.org with ESMTP id S932586AbWG1IQK convert rfc822-to-8bit (ORCPT ); Fri, 28 Jul 2006 04:16:10 -0400 From: "Rafael J. Wysocki" To: Andrew Morton Subject: [PATCH -mm][resend] Disable CPU hotplug during suspend Date: Fri, 28 Jul 2006 10:15:29 +0200 User-Agent: KMail/1.9.3 Cc: LKML , Pavel Machek MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200607281015.30048.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org The current suspend code has to be run on one CPU, so we use the CPU hotplug to take the non-boot CPUs offline on SMP machines.  However, we should also make sure that these CPUs will not be enabled by someone else after we have disabled them. The functions disable_nonboot_cpus() and enable_nonboot_cpus() are moved to kernel/cpu.c, because they now refer to some stuff in there that should better be static.  Also it's better if disable_nonboot_cpus() returns an error instead of panicking if something goes wrong, and enable_nonboot_cpus() has no reason to panic(), because the CPUs may have been enabled by the userland before it tries to take them online. Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek --- include/linux/cpu.h | 8 +++ include/linux/suspend.h | 8 --- kernel/cpu.c | 104 ++++++++++++++++++++++++++++++++++++++++++------ kernel/power/Makefile | 2 kernel/power/disk.c | 7 ++- kernel/power/main.c | 10 +--- kernel/power/smp.c | 62 ---------------------------- kernel/power/user.c | 14 ++++-- 8 files changed, 118 insertions(+), 97 deletions(-) Index: linux-2.6.18-rc2-mm1/include/linux/suspend.h =================================================================== --- linux-2.6.18-rc2-mm1.orig/include/linux/suspend.h 2006-07-28 08:34:46.000000000 +0200 +++ linux-2.6.18-rc2-mm1/include/linux/suspend.h 2006-07-28 08:37:11.000000000 +0200 @@ -57,14 +57,6 @@ static inline int software_suspend(void) } #endif /* CONFIG_PM */ -#ifdef CONFIG_SUSPEND_SMP -extern void disable_nonboot_cpus(void); -extern void enable_nonboot_cpus(void); -#else -static inline void disable_nonboot_cpus(void) {} -static inline void enable_nonboot_cpus(void) {} -#endif - void save_processor_state(void); void restore_processor_state(void); struct saved_context; Index: linux-2.6.18-rc2-mm1/kernel/power/smp.c =================================================================== --- linux-2.6.18-rc2-mm1.orig/kernel/power/smp.c 2006-06-18 03:49:35.000000000 +0200 +++ /dev/null 1970-01-01 00:00:00.000000000 +0000 @@ -1,62 +0,0 @@ -/* - * drivers/power/smp.c - Functions for stopping other CPUs. - * - * Copyright 2004 Pavel Machek - * Copyright (C) 2002-2003 Nigel Cunningham - * - * This file is released under the GPLv2. - */ - -#undef DEBUG - -#include -#include -#include -#include -#include -#include -#include - -/* This is protected by pm_sem semaphore */ -static cpumask_t frozen_cpus; - -void disable_nonboot_cpus(void) -{ - int cpu, error; - - error = 0; - cpus_clear(frozen_cpus); - printk("Freezing cpus ...\n"); - for_each_online_cpu(cpu) { - if (cpu == 0) - continue; - error = cpu_down(cpu); - if (!error) { - cpu_set(cpu, frozen_cpus); - printk("CPU%d is down\n", cpu); - continue; - } - printk("Error taking cpu %d down: %d\n", cpu, error); - } - BUG_ON(raw_smp_processor_id() != 0); - if (error) - panic("cpus not sleeping"); -} - -void enable_nonboot_cpus(void) -{ - int cpu, error; - - printk("Thawing cpus ...\n"); - for_each_cpu_mask(cpu, frozen_cpus) { - error = cpu_up(cpu); - if (!error) { - printk("CPU%d is up\n", cpu); - continue; - } - printk("Error taking cpu %d up: %d\n", cpu, error); - panic("Not enough cpus"); - } - cpus_clear(frozen_cpus); -} - Index: linux-2.6.18-rc2-mm1/kernel/power/disk.c =================================================================== --- linux-2.6.18-rc2-mm1.orig/kernel/power/disk.c 2006-07-28 08:36:24.000000000 +0200 +++ linux-2.6.18-rc2-mm1/kernel/power/disk.c 2006-07-28 10:17:02.000000000 +0200 @@ -18,6 +18,7 @@ #include #include #include +#include #include "power.h" @@ -72,7 +73,10 @@ static int prepare_processes(void) int error; pm_prepare_console(); - disable_nonboot_cpus(); + + error = disable_nonboot_cpus(); + if (error) + goto enable_cpus; if (freeze_processes()) { error = -EBUSY; @@ -84,6 +88,7 @@ static int prepare_processes(void) return 0; thaw: thaw_processes(); +enable_cpus: enable_nonboot_cpus(); pm_restore_console(); return error; Index: linux-2.6.18-rc2-mm1/kernel/power/main.c =================================================================== --- linux-2.6.18-rc2-mm1.orig/kernel/power/main.c 2006-07-28 08:36:24.000000000 +0200 +++ linux-2.6.18-rc2-mm1/kernel/power/main.c 2006-07-28 08:37:11.000000000 +0200 @@ -16,6 +16,7 @@ #include #include #include +#include #include "power.h" @@ -51,7 +52,7 @@ void pm_set_ops(struct pm_ops * ops) static int suspend_prepare(suspend_state_t state) { - int error = 0; + int error; unsigned int free_pages; if (!pm_ops || !pm_ops->enter) @@ -63,12 +64,9 @@ static int suspend_prepare(suspend_state pm_prepare_console(); - disable_nonboot_cpus(); - - if (num_online_cpus() != 1) { - error = -EPERM; + error = disable_nonboot_cpus(); + if (error) goto Enable_cpu; - } if (freeze_processes()) { error = -EAGAIN; Index: linux-2.6.18-rc2-mm1/kernel/power/user.c =================================================================== --- linux-2.6.18-rc2-mm1.orig/kernel/power/user.c 2006-07-28 08:36:24.000000000 +0200 +++ linux-2.6.18-rc2-mm1/kernel/power/user.c 2006-07-28 08:37:11.000000000 +0200 @@ -19,6 +19,7 @@ #include #include #include +#include #include @@ -139,12 +140,15 @@ static int snapshot_ioctl(struct inode * if (data->frozen) break; down(&pm_sem); - disable_nonboot_cpus(); - if (freeze_processes()) { - thaw_processes(); - enable_nonboot_cpus(); - error = -EBUSY; + error = disable_nonboot_cpus(); + if (!error) { + error = freeze_processes(); + if (error) { + thaw_processes(); + error = -EBUSY; + } } + enable_nonboot_cpus(); up(&pm_sem); if (!error) data->frozen = 1; Index: linux-2.6.18-rc2-mm1/include/linux/cpu.h =================================================================== --- linux-2.6.18-rc2-mm1.orig/include/linux/cpu.h 2006-07-28 08:36:23.000000000 +0200 +++ linux-2.6.18-rc2-mm1/include/linux/cpu.h 2006-07-28 08:37:11.000000000 +0200 @@ -89,4 +89,12 @@ int cpu_down(unsigned int cpu); static inline int cpu_is_offline(int cpu) { return 0; } #endif +#ifdef CONFIG_SUSPEND_SMP +extern int disable_nonboot_cpus(void); +extern void enable_nonboot_cpus(void); +#else +static inline int disable_nonboot_cpus(void) { return 0; } +static inline void enable_nonboot_cpus(void) {} +#endif + #endif /* _LINUX_CPU_H_ */ Index: linux-2.6.18-rc2-mm1/kernel/cpu.c =================================================================== --- linux-2.6.18-rc2-mm1.orig/kernel/cpu.c 2006-07-28 08:36:24.000000000 +0200 +++ linux-2.6.18-rc2-mm1/kernel/cpu.c 2006-07-28 08:51:17.000000000 +0200 @@ -21,6 +21,11 @@ static DEFINE_MUTEX(cpu_bitmask_lock); static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain); +/* If set, cpu_up and cpu_down will return -EPERM and do nothing. + * Should always be manipulated under cpu_add_remove_lock + */ +static int cpu_hotplug_disabled; + #ifdef CONFIG_HOTPLUG_CPU /* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */ @@ -108,30 +113,25 @@ static int take_cpu_down(void *unused) return 0; } -int cpu_down(unsigned int cpu) +/* Requires cpu_add_remove_lock to be held */ +static int __cpu_down(unsigned int cpu) { int err; struct task_struct *p; cpumask_t old_allowed, tmp; - mutex_lock(&cpu_add_remove_lock); - if (num_online_cpus() == 1) { - err = -EBUSY; - goto out; - } + if (num_online_cpus() == 1) + return -EBUSY; - if (!cpu_online(cpu)) { - err = -EINVAL; - goto out; - } + if (!cpu_online(cpu)) + return -EINVAL; err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, (void *)(long)cpu); if (err == NOTIFY_BAD) { printk("%s: attempt to take down CPU %u failed\n", __FUNCTION__, cpu); - err = -EINVAL; - goto out; + return -EINVAL; } /* Ensure that we are not runnable on dying cpu */ @@ -179,7 +179,19 @@ out_thread: err = kthread_stop(p); out_allowed: set_cpus_allowed(current, old_allowed); -out: + return err; +} + +int cpu_down(unsigned int cpu) +{ + int err = 0; + + mutex_lock(&cpu_add_remove_lock); + if (cpu_hotplug_disabled) + err = -EPERM; + else + err = __cpu_down(cpu); + mutex_unlock(&cpu_add_remove_lock); return err; } @@ -191,6 +203,11 @@ int __devinit cpu_up(unsigned int cpu) void *hcpu = (void *)(long)cpu; mutex_lock(&cpu_add_remove_lock); + if (cpu_hotplug_disabled) { + ret = -EPERM; + goto out; + } + if (cpu_online(cpu) || !cpu_present(cpu)) { ret = -EINVAL; goto out; @@ -223,3 +240,64 @@ out: mutex_unlock(&cpu_add_remove_lock); return ret; } + +#ifdef CONFIG_SUSPEND_SMP +static cpumask_t frozen_cpus; + +int disable_nonboot_cpus(void) +{ + int cpu, error = 0; + + /* We take all of the non-boot CPUs down in one shot to avoid races + * with the userspace trying to use the CPU hotplug at the same time + */ + mutex_lock(&cpu_add_remove_lock); + cpus_clear(frozen_cpus); + printk("Disabling non-boot CPUs ...\n"); + for_each_online_cpu(cpu) { + if (cpu == 0) + continue; + error = __cpu_down(cpu); + if (!error) { + cpu_set(cpu, frozen_cpus); + printk("CPU%d is down\n", cpu); + } else { + printk(KERN_ERR "Error taking CPU%d down: %d\n", + cpu, error); + break; + } + } + if (!error) { + BUG_ON(num_online_cpus() > 1); + BUG_ON(raw_smp_processor_id() != 0); + /* Make sure the CPUs won't be enabled by someone else */ + cpu_hotplug_disabled = 1; + } else { + printk(KERN_ERR "Non-boot CPUs are not disabled"); + } + mutex_unlock(&cpu_add_remove_lock); + return error; +} + +void enable_nonboot_cpus(void) +{ + int cpu, error; + + /* Allow everyone to use the CPU hotplug again */ + mutex_lock(&cpu_add_remove_lock); + cpu_hotplug_disabled = 0; + mutex_unlock(&cpu_add_remove_lock); + + printk("Enabling non-boot CPUs ...\n"); + for_each_cpu_mask(cpu, frozen_cpus) { + error = cpu_up(cpu); + if (!error) { + printk("CPU%d is up\n", cpu); + continue; + } + printk(KERN_WARNING "Error taking CPU%d up: %d\n", + cpu, error); + } + cpus_clear(frozen_cpus); +} +#endif Index: linux-2.6.18-rc2-mm1/kernel/power/Makefile =================================================================== --- linux-2.6.18-rc2-mm1.orig/kernel/power/Makefile 2006-06-18 03:49:35.000000000 +0200 +++ linux-2.6.18-rc2-mm1/kernel/power/Makefile 2006-07-28 08:37:11.000000000 +0200 @@ -7,6 +7,4 @@ obj-y := main.o process.o console.o obj-$(CONFIG_PM_LEGACY) += pm.o obj-$(CONFIG_SOFTWARE_SUSPEND) += swsusp.o disk.o snapshot.o swap.o user.o -obj-$(CONFIG_SUSPEND_SMP) += smp.o - obj-$(CONFIG_MAGIC_SYSRQ) += poweroff.o