[PATCH] revert "kthread: convert stop_machine into a kthread"

Jiri reports that the stop_machin kthread conversion caused his machine to
hang when suspending.  Hyperthreading is apparently involved.

I don't see why that would be and I can't reproduce it.  Revert to the 2.6.17
code.

Cc: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/stop_machine.c

@@ -4,7 +4,6 @@
 #include <linux/cpu.h>
 #include <linux/err.h>
 #include <linux/syscalls.h>
-#include <linux/kthread.h>
 #include <asm/atomic.h>
 #include <asm/semaphore.h>
 #include <asm/uaccess.h>
@@ -26,11 +25,13 @@ static unsigned int stopmachine_num_threads;
 static atomic_t stopmachine_thread_ack;
 static DECLARE_MUTEX(stopmachine_mutex);
 
-static int stopmachine(void *unused)
+static int stopmachine(void *cpu)
 {
 	int irqs_disabled = 0;
 	int prepared = 0;
 
+	set_cpus_allowed(current, cpumask_of_cpu((int)(long)cpu));
+
 	/* Ack: we are alive */
 	smp_mb(); /* Theoretically the ack = 0 might not be on this CPU yet. */
 	atomic_inc(&stopmachine_thread_ack);
@@ -84,8 +85,7 @@ static void stopmachine_set_state(enum stopmachine_state state)
 
 static int stop_machine(void)
 {
-	int ret = 0;
-	unsigned int i;
+	int i, ret = 0;
 	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 
 	/* One high-prio thread per cpu.  We'll do this one. */
@@ -96,16 +96,11 @@ static int stop_machine(void)
 	stopmachine_state = STOPMACHINE_WAIT;
 
 	for_each_online_cpu(i) {
-		struct task_struct *tsk;
 		if (i == raw_smp_processor_id())
 			continue;
-		tsk = kthread_create(stopmachine, NULL, "stopmachine");
-		if (IS_ERR(tsk)) {
-			ret = PTR_ERR(tsk);
+		ret = kernel_thread(stopmachine, (void *)(long)i,CLONE_KERNEL);
+		if (ret < 0)
 			break;
-		}
-		kthread_bind(tsk, i);
-		wake_up_process(tsk);
 		stopmachine_num_threads++;
 	}