diff options
Diffstat (limited to 'arch/i386')
| -rw-r--r-- | arch/i386/Kconfig | 9 | ||||
| -rw-r--r-- | arch/i386/kernel/apic.c | 3 | ||||
| -rw-r--r-- | arch/i386/kernel/io_apic.c | 2 | ||||
| -rw-r--r-- | arch/i386/kernel/irq.c | 67 | ||||
| -rw-r--r-- | arch/i386/kernel/process.c | 39 | ||||
| -rw-r--r-- | arch/i386/kernel/smp.c | 24 | ||||
| -rw-r--r-- | arch/i386/kernel/smpboot.c | 98 | ||||
| -rw-r--r-- | arch/i386/kernel/traps.c | 8 |
8 files changed, 221 insertions, 29 deletions
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index d4ae5f9ceae..b4cd11e5845 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -1250,6 +1250,15 @@ config SCx200 This support is also available as a module. If compiled as a module, it will be called scx200. +config HOTPLUG_CPU + bool "Support for hot-pluggable CPUs (EXPERIMENTAL)" + depends on SMP && HOTPLUG && EXPERIMENTAL + ---help--- + Say Y here to experiment with turning CPUs off and on. CPUs + can be controlled through /sys/devices/system/cpu. + + Say N. + source "drivers/pcmcia/Kconfig" source "drivers/pci/hotplug/Kconfig" diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c index 8d993fa7175..a28a088f3e7 100644 --- a/arch/i386/kernel/apic.c +++ b/arch/i386/kernel/apic.c @@ -26,6 +26,7 @@ #include <linux/mc146818rtc.h> #include <linux/kernel_stat.h> #include <linux/sysdev.h> +#include <linux/cpu.h> #include <asm/atomic.h> #include <asm/smp.h> @@ -1048,7 +1049,7 @@ void __init setup_secondary_APIC_clock(void) setup_APIC_timer(calibration_result); } -void __init disable_APIC_timer(void) +void __devinit disable_APIC_timer(void) { if (using_apic_timer) { unsigned long v; diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c index 08540bc4ba3..3c2b3bdfc80 100644 --- a/arch/i386/kernel/io_apic.c +++ b/arch/i386/kernel/io_apic.c @@ -576,9 +576,11 @@ static int balanced_irq(void *unused) try_to_freeze(PF_FREEZE); if (time_after(jiffies, prev_balance_time+balanced_irq_interval)) { + preempt_disable(); do_irq_balance(); prev_balance_time = jiffies; time_remaining = balanced_irq_interval; + preempt_enable(); } } return 0; diff --git a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c index 73945a3c53c..af115004aec 100644 --- a/arch/i386/kernel/irq.c +++ b/arch/i386/kernel/irq.c @@ -15,6 +15,9 @@ #include <linux/seq_file.h> #include <linux/interrupt.h> #include <linux/kernel_stat.h> +#include <linux/notifier.h> +#include <linux/cpu.h> +#include <linux/delay.h> DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_maxaligned_in_smp; EXPORT_PER_CPU_SYMBOL(irq_stat); @@ -210,9 +213,8 @@ int show_interrupts(struct seq_file *p, void *v) if (i == 0) { seq_printf(p, " "); - for (j=0; j<NR_CPUS; j++) - if (cpu_online(j)) - seq_printf(p, "CPU%d ",j); + for_each_cpu(j) + seq_printf(p, "CPU%d ",j); seq_putc(p, '\n'); } @@ -225,9 +227,8 @@ int show_interrupts(struct seq_file *p, void *v) #ifndef CONFIG_SMP seq_printf(p, "%10u ", kstat_irqs(i)); #else - for (j = 0; j < NR_CPUS; j++) - if (cpu_online(j)) - seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]); + for_each_cpu(j) + seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]); #endif seq_printf(p, " %14s", irq_desc[i].handler->typename); seq_printf(p, " %s", action->name); @@ -240,16 +241,14 @@ skip: spin_unlock_irqrestore(&irq_desc[i].lock, flags); } else if (i == NR_IRQS) { seq_printf(p, "NMI: "); - for (j = 0; j < NR_CPUS; j++) - if (cpu_online(j)) - seq_printf(p, "%10u ", nmi_count(j)); + for_each_cpu(j) + seq_printf(p, "%10u ", nmi_count(j)); seq_putc(p, '\n'); #ifdef CONFIG_X86_LOCAL_APIC seq_printf(p, "LOC: "); - for (j = 0; j < NR_CPUS; j++) - if (cpu_online(j)) - seq_printf(p, "%10u ", - per_cpu(irq_stat,j).apic_timer_irqs); + for_each_cpu(j) + seq_printf(p, "%10u ", + per_cpu(irq_stat,j).apic_timer_irqs); seq_putc(p, '\n'); #endif seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count)); @@ -259,3 +258,45 @@ skip: } return 0; } + +#ifdef CONFIG_HOTPLUG_CPU +#include <mach_apic.h> + +void fixup_irqs(cpumask_t map) +{ + unsigned int irq; + static int warned; + + for (irq = 0; irq < NR_IRQS; irq++) { + cpumask_t mask; + if (irq == 2) + continue; + + cpus_and(mask, irq_affinity[irq], map); + if (any_online_cpu(mask) == NR_CPUS) { + printk("Breaking affinity for irq %i\n", irq); + mask = map; + } + if (irq_desc[irq].handler->set_affinity) + irq_desc[irq].handler->set_affinity(irq, mask); + else if (irq_desc[irq].action && !(warned++)) + printk("Cannot set affinity for irq %i\n", irq); + } + +#if 0 + barrier(); + /* Ingo Molnar says: "after the IO-APIC masks have been redirected + [note the nop - the interrupt-enable boundary on x86 is two + instructions from sti] - to flush out pending hardirqs and + IPIs. After this point nothing is supposed to reach this CPU." */ + __asm__ __volatile__("sti; nop; cli"); + barrier(); +#else + /* That doesn't seem sufficient. Give it 1ms. */ + local_irq_enable(); + mdelay(1); + local_irq_disable(); +#endif +} +#endif + diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index aea2ce1145d..c1b11e8df60 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -13,6 +13,7 @@ #include <stdarg.h> +#include <linux/cpu.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/fs.h> @@ -55,6 +56,9 @@ #include <linux/irq.h> #include <linux/err.h> +#include <asm/tlbflush.h> +#include <asm/cpu.h> + asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); static int hlt_counter; @@ -143,14 +147,44 @@ static void poll_idle (void) } } +#ifdef CONFIG_HOTPLUG_CPU +#include <asm/nmi.h> +/* We don't actually take CPU down, just spin without interrupts. */ +static inline void play_dead(void) +{ + /* Ack it */ + __get_cpu_var(cpu_state) = CPU_DEAD; + + /* We shouldn't have to disable interrupts while dead, but + * some interrupts just don't seem to go away, and this makes + * it "work" for testing purposes. */ + /* Death loop */ + while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE) + cpu_relax(); + + local_irq_disable(); + __flush_tlb_all(); + cpu_set(smp_processor_id(), cpu_online_map); + enable_APIC_timer(); + local_irq_enable(); +} +#else +static inline void play_dead(void) +{ + BUG(); +} +#endif /* CONFIG_HOTPLUG_CPU */ + /* * The idle thread. There's no useful work to be * done, so just try to conserve power and have a * low exit latency (ie sit in a loop waiting for * somebody to say that they'd like to reschedule) */ -void cpu_idle (void) +void cpu_idle(void) { + int cpu = raw_smp_processor_id(); + /* endless idle loop with no priority at all */ while (1) { while (!need_resched()) { @@ -165,6 +199,9 @@ void cpu_idle (void) if (!idle) idle = default_idle; + if (cpu_is_offline(cpu)) + play_dead(); + __get_cpu_var(irq_stat).idle_timestamp = jiffies; idle(); } diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c index 68be7d0c723..35f521612b2 100644 --- a/arch/i386/kernel/smp.c +++ b/arch/i386/kernel/smp.c @@ -19,6 +19,7 @@ #include <linux/mc146818rtc.h> #include <linux/cache.h> #include <linux/interrupt.h> +#include <linux/cpu.h> #include <linux/module.h> #include <asm/mtrr.h> @@ -164,7 +165,7 @@ void send_IPI_mask_bitmask(cpumask_t cpumask, int vector) unsigned long flags; local_irq_save(flags); - + WARN_ON(mask & ~cpus_addr(cpu_online_map)[0]); /* * Wait for idle. */ @@ -346,21 +347,21 @@ out: static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm, unsigned long va) { - cpumask_t tmp; /* * A couple of (to be removed) sanity checks: * - * - we do not send IPIs to not-yet booted CPUs. * - current CPU must not be in mask * - mask must exist :) */ BUG_ON(cpus_empty(cpumask)); - - cpus_and(tmp, cpumask, cpu_online_map); - BUG_ON(!cpus_equal(cpumask, tmp)); BUG_ON(cpu_isset(smp_processor_id(), cpumask)); BUG_ON(!mm); + /* If a CPU which we ran on has gone down, OK. */ + cpus_and(cpumask, cpumask, cpu_online_map); + if (cpus_empty(cpumask)) + return; + /* * i'm not happy about this global shared spinlock in the * MM hot path, but we'll see how contended it is. @@ -476,6 +477,7 @@ void flush_tlb_all(void) */ void smp_send_reschedule(int cpu) { + WARN_ON(cpu_is_offline(cpu)); send_IPI_mask(cpumask_of_cpu(cpu), RESCHEDULE_VECTOR); } @@ -516,10 +518,15 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic, */ { struct call_data_struct data; - int cpus = num_online_cpus()-1; + int cpus; - if (!cpus) + /* Holding any lock stops cpus from going down. */ + spin_lock(&call_lock); + cpus = num_online_cpus() - 1; + if (!cpus) { + spin_unlock(&call_lock); return 0; + } /* Can deadlock when called with interrupts disabled */ WARN_ON(irqs_disabled()); @@ -531,7 +538,6 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic, if (wait) atomic_set(&data.finished, 0); - spin_lock(&call_lock); call_data = &data; mb(); diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c index c20d96d5c15..ad74a46e9ef 100644 --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -44,6 +44,9 @@ #include <linux/smp_lock.h> #include <linux/irq.h> #include <linux/bootmem.h> +#include <linux/notifier.h> +#include <linux/cpu.h> +#include <linux/percpu.h> #include <linux/delay.h> #include <linux/mc146818rtc.h> @@ -96,6 +99,9 @@ static int trampoline_exec; static void map_cpu_to_logical_apicid(void); +/* State of each CPU. */ +DEFINE_PER_CPU(int, cpu_state) = { 0 }; + /* * Currently trivial. Write the real->protected mode * bootstrap into the page concerned. The caller @@ -1119,6 +1125,9 @@ static void __init smp_boot_cpus(unsigned int max_cpus) who understands all this stuff should rewrite it properly. --RR 15/Jul/02 */ void __init smp_prepare_cpus(unsigned int max_cpus) { + smp_commenced_mask = cpumask_of_cpu(0); + cpu_callin_map = cpumask_of_cpu(0); + mb(); smp_boot_cpus(max_cpus); } @@ -1128,20 +1137,99 @@ void __devinit smp_prepare_boot_cpu(void) cpu_set(smp_processor_id(), cpu_callout_map); } -int __devinit __cpu_up(unsigned int cpu) +#ifdef CONFIG_HOTPLUG_CPU + +/* must be called with the cpucontrol mutex held */ +static int __devinit cpu_enable(unsigned int cpu) { - /* This only works at boot for x86. See "rewrite" above. */ - if (cpu_isset(cpu, smp_commenced_mask)) { - local_irq_enable(); - return -ENOSYS; + /* get the target out of its holding state */ + per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; + wmb(); + + /* wait for the processor to ack it. timeout? */ + while (!cpu_online(cpu)) + cpu_relax(); + + fixup_irqs(cpu_online_map); + /* counter the disable in fixup_irqs() */ + local_irq_enable(); + return 0; +} + +int __cpu_disable(void) +{ + cpumask_t map = cpu_online_map; + int cpu = smp_processor_id(); + + /* + * Perhaps use cpufreq to drop frequency, but that could go + * into generic code. + * + * We won't take down the boot processor on i386 due to some + * interrupts only being able to be serviced by the BSP. + * Especially so if we're not using an IOAPIC -zwane + */ + if (cpu == 0) + return -EBUSY; + + /* We enable the timer again on the exit path of the death loop */ + disable_APIC_timer(); + /* Allow any queued timer interrupts to get serviced */ + local_irq_enable(); + mdelay(1); + local_irq_disable(); + + cpu_clear(cpu, map); + fixup_irqs(map); + /* It's now safe to remove this processor from the online map */ + cpu_clear(cpu, cpu_online_map); + return 0; +} + +void __cpu_die(unsigned int cpu) +{ + /* We don't do anything here: idle task is faking death itself. */ + unsigned int i; + + for (i = 0; i < 10; i++) { + /* They ack this in play_dead by setting CPU_DEAD */ + if (per_cpu(cpu_state, cpu) == CPU_DEAD) + return; + current->state = TASK_UNINTERRUPTIBLE; + schedule_timeout(HZ/10); } + printk(KERN_ERR "CPU %u didn't die...\n", cpu); +} +#else /* ... !CONFIG_HOTPLUG_CPU */ +int __cpu_disable(void) +{ + return -ENOSYS; +} +void __cpu_die(unsigned int cpu) +{ + /* We said "no" in __cpu_disable */ + BUG(); +} +#endif /* CONFIG_HOTPLUG_CPU */ + +int __devinit __cpu_up(unsigned int cpu) +{ /* In case one didn't come up */ if (!cpu_isset(cpu, cpu_callin_map)) { + printk(KERN_DEBUG "skipping cpu%d, didn't come online\n", cpu); local_irq_enable(); return -EIO; } +#ifdef CONFIG_HOTPLUG_CPU + /* Already up, and in cpu_quiescent now? */ + if (cpu_isset(cpu, smp_commenced_mask)) { + cpu_enable(cpu); + return 0; + } +#endif + local_irq_enable(); /* Unleash the CPU! */ cpu_set(cpu, smp_commenced_mask); diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c index e4d4e2162c7..207ea8ba716 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -625,6 +625,14 @@ fastcall void do_nmi(struct pt_regs * regs, long error_code) nmi_enter(); cpu = smp_processor_id(); + +#ifdef CONFIG_HOTPLUG_CPU + if (!cpu_online(cpu)) { + nmi_exit(); + return; + } +#endif + ++nmi_count(cpu); if (!nmi_callback(regs, cpu)) |