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Message-Id: <12059478013647-git-send-email-gcosta@redhat.com>
Date: Wed, 19 Mar 2008 14:25:45 -0300
From: Glauber de Oliveira Costa <gcosta@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, tglx@...utronix.de, mingo@...e.hu,
ak@...e.de, Glauber Costa <gcosta@...hat.com>
Subject: [PATCH 50/79] [PATCH] use create_idle struct in do_boot_cpu
From: Glauber Costa <gcosta@...hat.com>
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 <gcosta@...hat.com>
---
arch/x86/kernel/smpboot_32.c | 86 ++++++++++++++++++++++++++++-------------
1 files changed, 59 insertions(+), 27 deletions(-)
diff --git a/arch/x86/kernel/smpboot_32.c b/arch/x86/kernel/smpboot_32.c
index c30abed..fc1eb52 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);
--
1.5.0.6
--
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