[PATCH] smp_processor_id() cleanup

This patch implements a number of smp_processor_id() cleanup ideas that
Arjan van de Ven and I came up with.

The previous __smp_processor_id/_smp_processor_id/smp_processor_id API
spaghetti was hard to follow both on the implementational and on the
usage side.

Some of the complexity arose from picking wrong names, some of the
complexity comes from the fact that not all architectures defined
__smp_processor_id.

In the new code, there are two externally visible symbols:

 - smp_processor_id(): debug variant.

 - raw_smp_processor_id(): nondebug variant. Replaces all existing
   uses of _smp_processor_id() and __smp_processor_id(). Defined
   by every SMP architecture in include/asm-*/smp.h.

There is one new internal symbol, dependent on DEBUG_PREEMPT:

 - debug_smp_processor_id(): internal debug variant, mapped to
                             smp_processor_id().

Also, i moved debug_smp_processor_id() from lib/kernel_lock.c into a new
lib/smp_processor_id.c file.  All related comments got updated and/or
clarified.

I have build/boot tested the following 8 .config combinations on x86:

 {SMP,UP} x {PREEMPT,!PREEMPT} x {DEBUG_PREEMPT,!DEBUG_PREEMPT}

I have also build/boot tested x64 on UP/PREEMPT/DEBUG_PREEMPT.  (Other
architectures are untested, but should work just fine.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 7 insertions, 7 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 83b3d376708..a566745dde6 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -379,7 +379,7 @@ static void module_unload_init(struct module *mod)
 	for (i = 0; i < NR_CPUS; i++)
 		local_set(&mod->ref[i].count, 0);
 	/* Hold reference count during initialization. */
-	local_set(&mod->ref[_smp_processor_id()].count, 1);
+	local_set(&mod->ref[raw_smp_processor_id()].count, 1);
 	/* Backwards compatibility macros put refcount during init. */
 	mod->waiter = current;
 }
diff --git a/kernel/power/smp.c b/kernel/power/smp.c
index cba3584b80f..457c2302ed4 100644
--- a/kernel/power/smp.c
+++ b/kernel/power/smp.c
@@ -48,11 +48,11 @@ void disable_nonboot_cpus(void)
 {
 	oldmask = current->cpus_allowed;
 	set_cpus_allowed(current, cpumask_of_cpu(0));
-	printk("Freezing CPUs (at %d)", _smp_processor_id());
+	printk("Freezing CPUs (at %d)", raw_smp_processor_id());
 	current->state = TASK_INTERRUPTIBLE;
 	schedule_timeout(HZ);
 	printk("...");
-	BUG_ON(_smp_processor_id() != 0);
+	BUG_ON(raw_smp_processor_id() != 0);
 
 	/* FIXME: for this to work, all the CPUs must be running
 	 * "idle" thread (or we deadlock). Is that guaranteed? */
diff --git a/kernel/sched.c b/kernel/sched.c
index f12a0c8a7d9..deca041fc36 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3814,7 +3814,7 @@ EXPORT_SYMBOL(yield);
  */
 void __sched io_schedule(void)
 {
-	struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
+	struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
 
 	atomic_inc(&rq->nr_iowait);
 	schedule();
@@ -3825,7 +3825,7 @@ EXPORT_SYMBOL(io_schedule);
 
 long __sched io_schedule_timeout(long timeout)
 {
-	struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
+	struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
 	long ret;
 
 	atomic_inc(&rq->nr_iowait);
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 6116b25aa7c..84a9d18aa8d 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -100,7 +100,7 @@ static int stop_machine(void)
 	stopmachine_state = STOPMACHINE_WAIT;
 
 	for_each_online_cpu(i) {
-		if (i == _smp_processor_id())
+		if (i == raw_smp_processor_id())
 			continue;
 		ret = kernel_thread(stopmachine, (void *)(long)i,CLONE_KERNEL);
 		if (ret < 0)
@@ -182,7 +182,7 @@ struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
 
 	/* If they don't care which CPU fn runs on, bind to any online one. */
 	if (cpu == NR_CPUS)
-		cpu = _smp_processor_id();
+		cpu = raw_smp_processor_id();
 
 	p = kthread_create(do_stop, &smdata, "kstopmachine");
 	if (!IS_ERR(p)) {