kernel: clean up USE_GENERIC_SMP_HELPERS

For arch which needs USE_GENERIC_SMP_HELPERS, it has to select
USE_GENERIC_SMP_HELPERS, rather than leaving a choice to user, since they
don't provide their own implementions.

Also, move on_each_cpu() to kernel/smp.c, it is strange to put it in
kernel/softirq.c.

For arch which doesn't use USE_GENERIC_SMP_HELPERS, e.g.  blackfin, only
on_each_cpu() is compiled.

Signed-off-by: Amerigo Wang <amwang@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/kernel/smp.c b/kernel/smp.c
index 12ed8b013e2d..4ec30e069987 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -13,6 +13,7 @@
 #include <linux/smp.h>
 #include <linux/cpu.h>
 
+#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
 static struct {
 	struct list_head	queue;
 	raw_spinlock_t		lock;
@@ -529,3 +530,21 @@ void ipi_call_unlock_irq(void)
 {
 	raw_spin_unlock_irq(&call_function.lock);
 }
+#endif /* USE_GENERIC_SMP_HELPERS */
+
+/*
+ * Call a function on all processors
+ */
+int on_each_cpu(void (*func) (void *info), void *info, int wait)
+{
+	int ret = 0;
+
+	preempt_disable();
+	ret = smp_call_function(func, info, wait);
+	local_irq_disable();
+	func(info);
+	local_irq_enable();
+	preempt_enable();
+	return ret;
+}
+EXPORT_SYMBOL(on_each_cpu);