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Subject[patch 06/18] x86: Use generic idle thread allocation
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
---
arch/x86/Kconfig | 1
arch/x86/include/asm/smp.h | 1
arch/x86/kernel/smpboot.c | 81 +++++----------------------------------------
arch/x86/xen/smp.c | 15 +-------
4 files changed, 14 insertions(+), 84 deletions(-)
Index: linux-2.6/arch/x86/Kconfig
===================================================================
--- linux-2.6.orig/arch/x86/Kconfig
+++ linux-2.6/arch/x86/Kconfig
@@ -82,6 +82,7 @@ config X86
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_IOMAP
select DCACHE_WORD_ACCESS if !DEBUG_PAGEALLOC
+ select GENERIC_SMP_IDLE_THREAD

config INSTRUCTION_DECODER
def_bool (KPROBES || PERF_EVENTS)
Index: linux-2.6/arch/x86/include/asm/smp.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/smp.h
+++ linux-2.6/arch/x86/include/asm/smp.h
@@ -164,6 +164,7 @@ int wbinvd_on_all_cpus(void);

void native_send_call_func_ipi(const struct cpumask *mask);
void native_send_call_func_single_ipi(int cpu);
+void x86_idle_thread_init(unsigned int cpu, struct task_struct *idle);

void smp_store_cpu_info(int id);
#define cpu_physical_id(cpu) per_cpu(x86_cpu_to_apicid, cpu)
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6/arch/x86/kernel/smpboot.c
@@ -76,20 +76,8 @@
/* 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))
-
-/*
* We need this for trampoline_base protection from concurrent accesses when
* off- and onlining cores wildly.
*/
@@ -97,20 +85,16 @@ static DEFINE_MUTEX(x86_cpu_hotplug_driv

void cpu_hotplug_driver_lock(void)
{
- mutex_lock(&x86_cpu_hotplug_driver_mutex);
+ mutex_lock(&x86_cpu_hotplug_driver_mutex);
}

void cpu_hotplug_driver_unlock(void)
{
- mutex_unlock(&x86_cpu_hotplug_driver_mutex);
+ mutex_unlock(&x86_cpu_hotplug_driver_mutex);
}

ssize_t arch_cpu_probe(const char *buf, size_t count) { return -1; }
ssize_t arch_cpu_release(const char *buf, size_t count) { return -1; }
-#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

/* Number of siblings per CPU package */
@@ -618,22 +602,6 @@ wakeup_secondary_cpu_via_init(int phys_a
return (send_status | accept_status);
}

-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);
-}
-
/* reduce the number of lines printed when booting a large cpu count system */
static void __cpuinit announce_cpu(int cpu, int apicid)
{
@@ -660,58 +628,31 @@ static void __cpuinit announce_cpu(int c
* Returns zero if CPU booted OK, else error code from
* ->wakeup_secondary_cpu.
*/
-static int __cpuinit do_boot_cpu(int apicid, int cpu)
+static int __cpuinit do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
{
unsigned long boot_error = 0;
unsigned long start_ip;
int timeout;
- struct create_idle c_idle = {
- .cpu = cpu,
- .done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
- };
-
- INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);

alternatives_smp_switch(1);

- c_idle.idle = get_idle_for_cpu(cpu);
-
- /*
- * We can't use kernel_thread since we must avoid to
- * reschedule the child.
- */
- 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;
- }
+ idle->thread.sp = (unsigned long) (((struct pt_regs *)
+ (THREAD_SIZE + task_stack_page(idle))) - 1);
+ per_cpu(current_task, cpu) = idle;

- schedule_work(&c_idle.work);
- wait_for_completion(&c_idle.done);
-
- if (IS_ERR(c_idle.idle)) {
- printk("failed fork for CPU %d\n", cpu);
- destroy_work_on_stack(&c_idle.work);
- return PTR_ERR(c_idle.idle);
- }
-
- set_idle_for_cpu(cpu, c_idle.idle);
-do_rest:
- per_cpu(current_task, cpu) = c_idle.idle;
#ifdef CONFIG_X86_32
/* Stack for startup_32 can be just as for start_secondary onwards */
irq_ctx_init(cpu);
#else
- clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
+ clear_tsk_thread_flag(idle, TIF_FORK);
initial_gs = per_cpu_offset(cpu);
per_cpu(kernel_stack, cpu) =
- (unsigned long)task_stack_page(c_idle.idle) -
+ (unsigned long)task_stack_page(idle) -
KERNEL_STACK_OFFSET + THREAD_SIZE;
#endif
early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
initial_code = (unsigned long)start_secondary;
- stack_start = c_idle.idle->thread.sp;
+ stack_start = idle->thread.sp;

/* start_ip had better be page-aligned! */
start_ip = trampoline_address();
@@ -813,8 +754,6 @@ do_rest:
*/
smpboot_restore_warm_reset_vector();
}
-
- destroy_work_on_stack(&c_idle.work);
return boot_error;
}

@@ -851,7 +790,7 @@ int __cpuinit native_cpu_up(unsigned int

per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;

- err = do_boot_cpu(apicid, cpu);
+ err = do_boot_cpu(apicid, cpu, tidle);
if (err) {
pr_debug("do_boot_cpu failed %d\n", err);
return -EIO;
Index: linux-2.6/arch/x86/xen/smp.c
===================================================================
--- linux-2.6.orig/arch/x86/xen/smp.c
+++ linux-2.6/arch/x86/xen/smp.c
@@ -250,18 +250,8 @@ static void __init xen_smp_prepare_cpus(
set_cpu_possible(cpu, false);
}

- for_each_possible_cpu (cpu) {
- struct task_struct *idle;
-
- if (cpu == 0)
- continue;
-
- idle = fork_idle(cpu);
- if (IS_ERR(idle))
- panic("failed fork for CPU %d", cpu);
-
+ for_each_possible_cpu(cpu)
set_cpu_present(cpu, true);
- }
}

static int __cpuinit
@@ -331,9 +321,8 @@ cpu_initialize_context(unsigned int cpu,
return 0;
}

-static int __cpuinit xen_cpu_up(unsigned int cpu, struct task_struct *tidle)
+static int __cpuinit xen_cpu_up(unsigned int cpu, struct task_struct *idle)
{
- struct task_struct *idle = idle_task(cpu);
int rc;

per_cpu(current_task, cpu) = idle;



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