From: Nick Piggin <nickpiggin@yahoo.com.au>
Clean up init_idle to not use wake_up_forked_process, then undo all the stuff
that call does. Instead, do everything in init_idle.
Make double_rq_lock depend on CONFIG_SMP because it is no longer used on UP.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/alpha/kernel/smp.c | 2
25-akpm/arch/i386/kernel/smpboot.c | 7 --
25-akpm/arch/i386/mach-voyager/voyager_smp.c | 5 +
25-akpm/arch/ia64/kernel/smpboot.c | 7 --
25-akpm/arch/mips/kernel/smp.c | 8 --
25-akpm/arch/parisc/kernel/smp.c | 1
25-akpm/arch/ppc/kernel/smp.c | 2
25-akpm/arch/ppc64/kernel/smp.c | 1
25-akpm/arch/s390/kernel/smp.c | 5 +
25-akpm/arch/sh/kernel/smp.c | 2
25-akpm/arch/x86_64/kernel/smpboot.c | 7 --
25-akpm/init/main.c | 15 ++---
25-akpm/kernel/sched.c | 77 +++++++++++++--------------
13 files changed, 61 insertions(+), 78 deletions(-)
diff -puN arch/alpha/kernel/smp.c~sched-clean-init-idle arch/alpha/kernel/smp.c
--- 25/arch/alpha/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.649706552 -0700
+++ 25-akpm/arch/alpha/kernel/smp.c 2004-08-15 22:47:20.678702144 -0700
@@ -439,8 +439,6 @@ smp_boot_one_cpu(int cpuid)
if (IS_ERR(idle))
panic("failed fork for CPU %d", cpuid);
- wake_up_forked_process(idle);
-
init_idle(idle, cpuid);
unhash_process(idle);
diff -puN arch/i386/kernel/smpboot.c~sched-clean-init-idle arch/i386/kernel/smpboot.c
--- 25/arch/i386/kernel/smpboot.c~sched-clean-init-idle 2004-08-15 22:47:20.650706400 -0700
+++ 25-akpm/arch/i386/kernel/smpboot.c 2004-08-15 22:47:20.679701992 -0700
@@ -804,16 +804,13 @@ static int __init do_boot_cpu(int apicid
idle = fork_by_hand();
if (IS_ERR(idle))
panic("failed fork for CPU %d", cpu);
- wake_up_forked_process(idle);
- /*
- * We remove it from the pidhash and the runqueue
- * once we got the process:
- */
+ /* Make this the idle thread */
init_idle(idle, cpu);
idle->thread.eip = (unsigned long) start_secondary;
+ /* Remove it from the pidhash */
unhash_process(idle);
/* start_eip had better be page-aligned! */
diff -puN arch/i386/mach-voyager/voyager_smp.c~sched-clean-init-idle arch/i386/mach-voyager/voyager_smp.c
--- 25/arch/i386/mach-voyager/voyager_smp.c~sched-clean-init-idle 2004-08-15 22:47:20.652706096 -0700
+++ 25-akpm/arch/i386/mach-voyager/voyager_smp.c 2004-08-15 22:47:20.681701688 -0700
@@ -591,11 +591,12 @@ do_boot_cpu(__u8 cpu)
if(IS_ERR(idle))
panic("failed fork for CPU%d", cpu);
- wake_up_forked_process(idle);
-
+ /* Make this the idle thread */
init_idle(idle, cpu);
idle->thread.eip = (unsigned long) start_secondary;
+
+ /* Remove it from the pidhash */
unhash_process(idle);
/* init_tasks (in sched.c) is indexed logically */
stack_start.esp = (void *) idle->thread.esp;
diff -puN arch/ia64/kernel/smpboot.c~sched-clean-init-idle arch/ia64/kernel/smpboot.c
--- 25/arch/ia64/kernel/smpboot.c~sched-clean-init-idle 2004-08-15 22:47:20.653705944 -0700
+++ 25-akpm/arch/ia64/kernel/smpboot.c 2004-08-15 22:47:20.681701688 -0700
@@ -400,14 +400,11 @@ do_boot_cpu (int sapicid, int cpu)
if (IS_ERR(c_idle.idle))
panic("failed fork for CPU %d", cpu);
- wake_up_forked_process(c_idle.idle);
- /*
- * We remove it from the pidhash and the runqueue
- * once we got the process:
- */
+ /* Make this the idle thread */
init_idle(c_idle.idle, cpu);
+ /* Remove it from the pidhash */
unhash_process(c_idle.idle);
task_for_booting_cpu = c_idle.idle;
diff -puN arch/mips/kernel/smp.c~sched-clean-init-idle arch/mips/kernel/smp.c
--- 25/arch/mips/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.654705792 -0700
+++ 25-akpm/arch/mips/kernel/smp.c 2004-08-15 22:47:20.682701536 -0700
@@ -279,14 +279,10 @@ static int __init do_boot_cpu(int cpu)
if (IS_ERR(idle))
panic("failed fork for CPU %d\n", cpu);
- wake_up_forked_process(idle);
-
- /*
- * We remove it from the pidhash and the runqueue once we've
- * got the process:
- */
+ /* Make this the idle thread */
init_idle(idle, cpu);
+ /* Remove it from the pidhash */
unhash_process(idle);
prom_boot_secondary(cpu, idle);
diff -puN arch/parisc/kernel/smp.c~sched-clean-init-idle arch/parisc/kernel/smp.c
--- 25/arch/parisc/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.656705488 -0700
+++ 25-akpm/arch/parisc/kernel/smp.c 2004-08-15 22:47:20.683701384 -0700
@@ -525,7 +525,6 @@ int __init smp_boot_one_cpu(int cpuid)
if (IS_ERR(idle))
panic("SMP: fork failed for CPU:%d", cpuid);
- wake_up_forked_process(idle);
init_idle(idle, cpuid);
unhash_process(idle);
idle->thread_info->cpu = cpuid;
diff -puN arch/ppc64/kernel/smp.c~sched-clean-init-idle arch/ppc64/kernel/smp.c
--- 25/arch/ppc64/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.657705336 -0700
+++ 25-akpm/arch/ppc64/kernel/smp.c 2004-08-15 22:47:20.686700928 -0700
@@ -809,7 +809,6 @@ static void __init smp_create_idle(unsig
if (IS_ERR(p))
panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
- wake_up_forked_process(p);
init_idle(p, cpu);
unhash_process(p);
diff -puN arch/ppc/kernel/smp.c~sched-clean-init-idle arch/ppc/kernel/smp.c
--- 25/arch/ppc/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.658705184 -0700
+++ 25-akpm/arch/ppc/kernel/smp.c 2004-08-15 22:47:20.687700776 -0700
@@ -375,8 +375,6 @@ int __cpu_up(unsigned int cpu)
p = copy_process(CLONE_VM|CLONE_IDLETASK, 0, ®s, 0, NULL, NULL);
if (IS_ERR(p))
panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
- wake_up_forked_process(p);
-
init_idle(p, cpu);
unhash_process(p);
diff -puN arch/s390/kernel/smp.c~sched-clean-init-idle arch/s390/kernel/smp.c
--- 25/arch/s390/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.667703816 -0700
+++ 25-akpm/arch/s390/kernel/smp.c 2004-08-15 22:47:20.687700776 -0700
@@ -574,9 +574,12 @@ static void __init smp_create_idle(unsig
if (IS_ERR(p))
panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
- wake_up_forked_process(p);
+ /* Make this the idle thread */
init_idle(p, cpu);
+
+ /* Remove it from the pidhash */
unhash_process(p);
+
current_set[cpu] = p;
}
diff -puN arch/sh/kernel/smp.c~sched-clean-init-idle arch/sh/kernel/smp.c
--- 25/arch/sh/kernel/smp.c~sched-clean-init-idle 2004-08-15 22:47:20.670703360 -0700
+++ 25-akpm/arch/sh/kernel/smp.c 2004-08-15 22:47:20.688700624 -0700
@@ -106,8 +106,6 @@ int __cpu_up(unsigned int cpu)
if (IS_ERR(tsk))
panic("Failed forking idle task for cpu %d\n", cpu);
- wake_up_forked_process(tsk);
-
init_idle(tsk, cpu);
unhash_process(tsk);
diff -puN arch/x86_64/kernel/smpboot.c~sched-clean-init-idle arch/x86_64/kernel/smpboot.c
--- 25/arch/x86_64/kernel/smpboot.c~sched-clean-init-idle 2004-08-15 22:47:20.671703208 -0700
+++ 25-akpm/arch/x86_64/kernel/smpboot.c 2004-08-15 22:47:20.689700472 -0700
@@ -578,15 +578,12 @@ static void __init do_boot_cpu (int apic
idle = fork_by_hand();
if (IS_ERR(idle))
panic("failed fork for CPU %d", cpu);
- wake_up_forked_process(idle);
x86_cpu_to_apicid[cpu] = apicid;
- /*
- * We remove it from the pidhash and the runqueue
- * once we got the process:
- */
+ /* Make this the idle thread */
init_idle(idle,cpu);
+ /* Remove it from the pidhash */
unhash_process(idle);
cpu_pda[cpu].pcurrent = idle;
diff -puN init/main.c~sched-clean-init-idle init/main.c
--- 25/init/main.c~sched-clean-init-idle 2004-08-15 22:47:20.672703056 -0700
+++ 25-akpm/init/main.c 2004-08-15 22:47:20.689700472 -0700
@@ -471,6 +471,14 @@ asmlinkage void __init start_kernel(void
*/
sched_init();
+ /*
+ * Make us the idle thread. Technically, schedule() should not be
+ * called from this thread, however somewhere below it might be,
+ * but because we are the idle thread, we just pick up running again
+ * when this runqueue becomes "idle".
+ */
+ init_idle(current, smp_processor_id());
+
build_all_zonelists();
page_alloc_init();
trap_init();
@@ -537,13 +545,6 @@ asmlinkage void __init start_kernel(void
acpi_early_init(); /* before LAPIC and SMP init */
- /*
- * We count on the initial thread going ok
- * Like idlers init is an unlocked kernel thread, which will
- * make syscalls (and thus be locked).
- */
- init_idle(current, smp_processor_id());
-
/* Do the rest non-__init'ed, we're now alive */
rest_init();
}
diff -puN kernel/sched.c~sched-clean-init-idle kernel/sched.c
--- 25/kernel/sched.c~sched-clean-init-idle 2004-08-15 22:47:20.674702752 -0700
+++ 25-akpm/kernel/sched.c 2004-08-15 22:47:20.692700016 -0700
@@ -1122,6 +1122,15 @@ unsigned long nr_iowait(void)
return sum;
}
+enum idle_type
+{
+ IDLE,
+ NOT_IDLE,
+ NEWLY_IDLE,
+};
+
+#ifdef CONFIG_SMP
+
/*
* double_rq_lock - safely lock two runqueues
*
@@ -1156,14 +1165,20 @@ static void double_rq_unlock(runqueue_t
spin_unlock(&rq2->lock);
}
-enum idle_type
+/*
+ * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
+ */
+static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
{
- IDLE,
- NOT_IDLE,
- NEWLY_IDLE,
-};
-
-#ifdef CONFIG_SMP
+ if (unlikely(!spin_trylock(&busiest->lock))) {
+ if (busiest < this_rq) {
+ spin_unlock(&this_rq->lock);
+ spin_lock(&busiest->lock);
+ spin_lock(&this_rq->lock);
+ } else
+ spin_lock(&busiest->lock);
+ }
+}
/*
* find_idlest_cpu - find the least busy runqueue.
@@ -1359,21 +1374,6 @@ out:
}
/*
- * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
- */
-static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
-{
- if (unlikely(!spin_trylock(&busiest->lock))) {
- if (busiest < this_rq) {
- spin_unlock(&this_rq->lock);
- spin_lock(&busiest->lock);
- spin_lock(&this_rq->lock);
- } else
- spin_lock(&busiest->lock);
- }
-}
-
-/*
* pull_task - move a task from a remote runqueue to the local runqueue.
* Both runqueues must be locked.
*/
@@ -2210,6 +2210,15 @@ need_resched:
prev = current;
rq = this_rq();
+ /*
+ * The idle thread is not allowed to schedule!
+ * Remove this check after it has been exercised a bit.
+ */
+ if (unlikely(current == rq->idle) && current->state != TASK_RUNNING) {
+ printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+ dump_stack();
+ }
+
release_kernel_lock(prev);
now = sched_clock();
if (likely(now - prev->timestamp < NS_MAX_SLEEP_AVG))
@@ -3276,21 +3285,20 @@ void show_state(void)
void __devinit init_idle(task_t *idle, int cpu)
{
- runqueue_t *idle_rq = cpu_rq(cpu), *rq = cpu_rq(task_cpu(idle));
+ runqueue_t *rq = cpu_rq(cpu);
unsigned long flags;
- local_irq_save(flags);
- double_rq_lock(idle_rq, rq);
-
- idle_rq->curr = idle_rq->idle = idle;
- deactivate_task(idle, rq);
+ idle->sleep_avg = 0;
+ idle->interactive_credit = 0;
idle->array = NULL;
idle->prio = MAX_PRIO;
idle->state = TASK_RUNNING;
set_task_cpu(idle, cpu);
- double_rq_unlock(idle_rq, rq);
+
+ spin_lock_irqsave(&rq->lock, flags);
+ rq->curr = rq->idle = idle;
set_tsk_need_resched(idle);
- local_irq_restore(flags);
+ spin_unlock_irqrestore(&rq->lock, flags);
/* Set the preempt count _outside_ the spinlocks! */
#ifdef CONFIG_PREEMPT
@@ -3969,15 +3977,6 @@ void __init sched_init(void)
__set_bit(MAX_PRIO, array->bitmap);
}
}
- /*
- * We have to do a little magic to get the first
- * thread right in SMP mode.
- */
- rq = this_rq();
- rq->curr = current;
- rq->idle = current;
- set_task_cpu(current, smp_processor_id());
- wake_up_forked_process(current);
/*
* The boot idle thread does lazy MMU switching as well:
_