Add a bunch of cycle_kernel_lock() calls

All of the open() functions which don't need the BKL on their face may
still depend on its acquisition to serialize opens against driver
initialization.  So make those functions acquire then release the BKL to be
on the safe side.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/drivers/char/scx200_gpio.c b/drivers/char/scx200_gpio.c
index be2c623..1d91005 100644
--- a/drivers/char/scx200_gpio.c
+++ b/drivers/char/scx200_gpio.c
@@ -12,6 +12,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
+#include <linux/smp_lock.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 
@@ -46,12 +47,12 @@
 };
 EXPORT_SYMBOL_GPL(scx200_gpio_ops);
 
-/* No BKL needed here: no global resources used */
 static int scx200_gpio_open(struct inode *inode, struct file *file)
 {
 	unsigned m = iminor(inode);
 	file->private_data = &scx200_gpio_ops;
 
+	cycle_kernel_lock();
 	if (m >= MAX_PINS)
 		return -EINVAL;
 	return nonseekable_open(inode, file);