From: Russell King <rmk@dyn-67.arm.linux.org.uk>
Date: Wed, 2 Nov 2005 21:51:40 +0000 (+0000)
Subject: [ARM SMP] Track CPU idle threads
X-Git-Tag: v2.6.15-rc1~450^2~4^2~2
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=71f512e89704f5aa6fc0b97e4a719184080b8938;p=linux-2.6

[ARM SMP] Track CPU idle threads

Track the idle thread task_struct for each CPU.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8261649457..45877f5d57 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -80,19 +80,23 @@ static DEFINE_SPINLOCK(smp_call_function_lock);
 
 int __cpuinit __cpu_up(unsigned int cpu)
 {
-	struct task_struct *idle;
+	struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
+	struct task_struct *idle = ci->idle;
 	pgd_t *pgd;
 	pmd_t *pmd;
 	int ret;
 
 	/*
-	 * Spawn a new process manually.  Grab a pointer to
-	 * its task struct so we can mess with it
+	 * Spawn a new process manually, if not already done.
+	 * Grab a pointer to its task struct so we can mess with it
 	 */
-	idle = fork_idle(cpu);
-	if (IS_ERR(idle)) {
-		printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
-		return PTR_ERR(idle);
+	if (!idle) {
+		idle = fork_idle(cpu);
+		if (IS_ERR(idle)) {
+			printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
+			return PTR_ERR(idle);
+		}
+		ci->idle = idle;
 	}
 
 	/*
@@ -236,6 +240,8 @@ void __init smp_prepare_boot_cpu(void)
 {
 	unsigned int cpu = smp_processor_id();
 
+	per_cpu(cpu_data, cpu).idle = current;
+
 	cpu_set(cpu, cpu_possible_map);
 	cpu_set(cpu, cpu_present_map);
 	cpu_set(cpu, cpu_online_map);
diff --git a/include/asm-arm/cpu.h b/include/asm-arm/cpu.h
index fcbdd40cb6..751bc74620 100644
--- a/include/asm-arm/cpu.h
+++ b/include/asm-arm/cpu.h
@@ -16,6 +16,7 @@
 struct cpuinfo_arm {
 	struct cpu	cpu;
 #ifdef CONFIG_SMP
+	struct task_struct *idle;
 	unsigned int	loops_per_jiffy;
 #endif
 };