diff options
Diffstat (limited to 'arch/powerpc/kernel')
-rw-r--r-- | arch/powerpc/kernel/smp.c | 100 |
1 files changed, 78 insertions, 22 deletions
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index d7f8cc18ae05..54faff91b805 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -57,6 +57,25 @@ #define DBG(fmt...) #endif + +/* Store all idle threads, this can be reused instead of creating +* a new thread. Also avoids complicated thread destroy functionality +* for idle threads. +*/ +#ifdef CONFIG_HOTPLUG_CPU +/* + * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is + * removed after init for !CONFIG_HOTPLUG_CPU. + */ +static DEFINE_PER_CPU(struct task_struct *, idle_thread_array); +#define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x)) +#define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p)) +#else +static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ; +#define get_idle_for_cpu(x) (idle_thread_array[(x)]) +#define set_idle_for_cpu(x, p) (idle_thread_array[(x)] = (p)) +#endif + struct thread_info *secondary_ti; DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map); @@ -238,23 +257,6 @@ static void __devinit smp_store_cpu_info(int id) per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR); } -static void __init smp_create_idle(unsigned int cpu) -{ - struct task_struct *p; - - /* create a process for the processor */ - p = fork_idle(cpu); - if (IS_ERR(p)) - panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p)); -#ifdef CONFIG_PPC64 - paca[cpu].__current = p; - paca[cpu].kstack = (unsigned long) task_thread_info(p) - + THREAD_SIZE - STACK_FRAME_OVERHEAD; -#endif - current_set[cpu] = task_thread_info(p); - task_thread_info(p)->cpu = cpu; -} - void __init smp_prepare_cpus(unsigned int max_cpus) { unsigned int cpu; @@ -288,10 +290,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus) max_cpus = NR_CPUS; else max_cpus = 1; - - for_each_possible_cpu(cpu) - if (cpu != boot_cpuid) - smp_create_idle(cpu); } void __devinit smp_prepare_boot_cpu(void) @@ -355,9 +353,62 @@ void generic_set_cpu_dead(unsigned int cpu) } #endif +struct create_idle { + struct work_struct work; + struct task_struct *idle; + struct completion done; + int cpu; +}; + +static void __cpuinit do_fork_idle(struct work_struct *work) +{ + struct create_idle *c_idle = + container_of(work, struct create_idle, work); + + c_idle->idle = fork_idle(c_idle->cpu); + complete(&c_idle->done); +} + +static int __cpuinit create_idle(unsigned int cpu) +{ + struct thread_info *ti; + struct create_idle c_idle = { + .cpu = cpu, + .done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done), + }; + INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle); + + c_idle.idle = get_idle_for_cpu(cpu); + + /* We can't use kernel_thread since we must avoid to + * reschedule the child. We use a workqueue because + * we want to fork from a kernel thread, not whatever + * userspace process happens to be trying to online us. + */ + if (!c_idle.idle) { + schedule_work(&c_idle.work); + wait_for_completion(&c_idle.done); + } else + init_idle(c_idle.idle, cpu); + if (IS_ERR(c_idle.idle)) { + pr_err("Failed fork for CPU %u: %li", cpu, PTR_ERR(c_idle.idle)); + return PTR_ERR(c_idle.idle); + } + ti = task_thread_info(c_idle.idle); + +#ifdef CONFIG_PPC64 + paca[cpu].__current = c_idle.idle; + paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD; +#endif + ti->cpu = cpu; + current_set[cpu] = ti; + + return 0; +} + int __cpuinit __cpu_up(unsigned int cpu) { - int c; + int rc, c; secondary_ti = current_set[cpu]; @@ -365,6 +416,11 @@ int __cpuinit __cpu_up(unsigned int cpu) (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu))) return -EINVAL; + /* Make sure we have an idle thread */ + rc = create_idle(cpu); + if (rc) + return rc; + /* Make sure callin-map entry is 0 (can be leftover a CPU * hotplug */ |