From 365c894c65b98da944992199ea24206f531674de Mon Sep 17 00:00:00 2001 From: Glauber de Oliveira Costa Date: Wed, 19 Mar 2008 14:25:45 -0300 Subject: [PATCH] x86: use create_idle struct in do_boot_cpu Use a new worker, with help of the create_idle struct to fork the idle thread. We now have two workers, the first of them triggered by __smp_prepare_cpu. But the later is going away soon. Signed-off-by: Glauber Costa Signed-off-by: Ingo Molnar --- arch/x86/kernel/smpboot_32.c | 86 +++++++++++++++++++++++++----------- 1 file changed, 59 insertions(+), 27 deletions(-) diff --git a/arch/x86/kernel/smpboot_32.c b/arch/x86/kernel/smpboot_32.c index c30abed08923..fc1eb5255f66 100644 --- a/arch/x86/kernel/smpboot_32.c +++ b/arch/x86/kernel/smpboot_32.c @@ -79,6 +79,24 @@ static void map_cpu_to_logical_apicid(void); /* State of each CPU. */ DEFINE_PER_CPU(int, cpu_state) = { 0 }; +/* 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 +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 + static atomic_t init_deasserted; static void __cpuinit smp_callin(void) @@ -513,30 +531,21 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip) extern cpumask_t cpu_initialized; -#ifdef CONFIG_HOTPLUG_CPU -static struct task_struct * __cpuinitdata cpu_idle_tasks[NR_CPUS]; -static inline struct task_struct * __cpuinit alloc_idle_task(int cpu) -{ +struct create_idle { + struct work_struct work; struct task_struct *idle; + struct completion done; + int cpu; +}; - if ((idle = cpu_idle_tasks[cpu]) != NULL) { - /* initialize thread_struct. we really want to avoid destroy - * idle tread - */ - idle->thread.sp = (unsigned long)task_pt_regs(idle); - init_idle(idle, cpu); - return idle; - } - idle = fork_idle(cpu); +static void __cpuinit do_fork_idle(struct work_struct *work) +{ + struct create_idle *c_idle = + container_of(work, struct create_idle, work); - if (!IS_ERR(idle)) - cpu_idle_tasks[cpu] = idle; - return idle; + c_idle->idle = fork_idle(c_idle->cpu); + complete(&c_idle->done); } -#else -#define alloc_idle_task(cpu) fork_idle(cpu) -#endif - static int __cpuinit do_boot_cpu(int apicid, int cpu) /* * NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad @@ -544,11 +553,15 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu) * Returns zero if CPU booted OK, else error code from wakeup_secondary_cpu. */ { - struct task_struct *idle; unsigned long boot_error; int timeout; unsigned long start_eip; unsigned short nmi_high = 0, nmi_low = 0; + struct create_idle c_idle = { + .cpu = cpu, + .done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done), + }; + INIT_WORK(&c_idle.work, do_fork_idle); /* * Save current MTRR state in case it was changed since early boot @@ -556,19 +569,38 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu) */ mtrr_save_state(); + c_idle.idle = get_idle_for_cpu(cpu); + /* * We can't use kernel_thread since we must avoid to * reschedule the child. */ - idle = alloc_idle_task(cpu); - if (IS_ERR(idle)) - panic("failed fork for CPU %d", cpu); + if (c_idle.idle) { + c_idle.idle->thread.sp = (unsigned long) (((struct pt_regs *) + (THREAD_SIZE + task_stack_page(c_idle.idle))) - 1); + init_idle(c_idle.idle, cpu); + goto do_rest; + } + + if (!keventd_up() || current_is_keventd()) + c_idle.work.func(&c_idle.work); + else { + schedule_work(&c_idle.work); + wait_for_completion(&c_idle.done); + } + + if (IS_ERR(c_idle.idle)) { + printk(KERN_ERR "failed fork for CPU %d\n", cpu); + return PTR_ERR(c_idle.idle); + } + set_idle_for_cpu(cpu, c_idle.idle); +do_rest: + per_cpu(current_task, cpu) = c_idle.idle; init_gdt(cpu); - per_cpu(current_task, cpu) = idle; early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu); - idle->thread.ip = (unsigned long) start_secondary; + c_idle.idle->thread.ip = (unsigned long) start_secondary; /* start_eip had better be page-aligned! */ start_eip = setup_trampoline(); @@ -577,7 +609,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu) /* So we see what's up */ printk("Booting processor %d/%d ip %lx\n", cpu, apicid, start_eip); /* Stack for startup_32 can be just as for start_secondary onwards */ - stack_start.sp = (void *) idle->thread.sp; + stack_start.sp = (void *) c_idle.idle->thread.sp; irq_ctx_init(cpu); -- 2.20.1