macintosh: Remove BKL from ans-lcd

The ans-lcd driver got the cycle_kernel_lock() in anslcd_open() from
the BKL pushdown and it still uses the locked ioctl.

The BKL serialization in this driver is more than obscure and
definitely does not cover all possible corner cases. Protect the
access to the hardware with a local mutex and get rid of BKL and
locked ioctl.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20091010153349.966159859@linutronix.de>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

drivers/macintosh/ans-lcd.c

@@ -3,7 +3,6 @@
  */
 
 #include <linux/types.h>
-#include <linux/smp_lock.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
@@ -26,6 +25,7 @@
 static unsigned long anslcd_short_delay = 80;
 static unsigned long anslcd_long_delay = 3280;
 static volatile unsigned char __iomem *anslcd_ptr;
+static DEFINE_MUTEX(anslcd_mutex);
 
 #undef DEBUG
 
@@ -65,26 +65,31 @@ anslcd_write( struct file * file, const char __user * buf,
 
 	if (!access_ok(VERIFY_READ, buf, count))
 		return -EFAULT;
+
+	mutex_lock(&anslcd_mutex);
 	for ( i = *ppos; count > 0; ++i, ++p, --count ) 
 	{
 		char c;
 		__get_user(c, p);
 		anslcd_write_byte_data( c );
 	}
+	mutex_unlock(&anslcd_mutex);
 	*ppos = i;
 	return p - buf;
 }
 
-static int
-anslcd_ioctl( struct inode * inode, struct file * file,
-				unsigned int cmd, unsigned long arg )
+static long
+anslcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	char ch, __user *temp;
+	long ret = 0;
 
 #ifdef DEBUG
 	printk(KERN_DEBUG "LCD: ioctl(%d,%d)\n",cmd,arg);
 #endif
 
+	mutex_lock(&anslcd_mutex);
+
 	switch ( cmd )
 	{
 	case ANSLCD_CLEAR:
@@ -93,41 +98,45 @@ anslcd_ioctl( struct inode * inode, struct file * file,
 		anslcd_write_byte_ctrl ( 0x06 );
 		anslcd_write_byte_ctrl ( 0x01 );
 		anslcd_write_byte_ctrl ( 0x02 );
-		return 0;
+		break;
 	case ANSLCD_SENDCTRL:
 		temp = (char __user *) arg;
 		__get_user(ch, temp);
 		for (; ch; temp++) { /* FIXME: This is ugly, but should work, as a \0 byte is not a valid command code */
 			anslcd_write_byte_ctrl ( ch );
 			__get_user(ch, temp);
 		}
-		return 0;
+		break;
 	case ANSLCD_SETSHORTDELAY:
 		if (!capable(CAP_SYS_ADMIN))
-			return -EACCES;
-		anslcd_short_delay=arg;
-		return 0;
+			ret =-EACCES;
+		else
+			anslcd_short_delay=arg;
+		break;
 	case ANSLCD_SETLONGDELAY:
 		if (!capable(CAP_SYS_ADMIN))
-			return -EACCES;
-		anslcd_long_delay=arg;
-		return 0;
+			ret = -EACCES;
+		else
+			anslcd_long_delay=arg;
+		break;
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
+
+	mutex_unlock(&anslcd_mutex);
+	return ret;
 }
 
 static int
 anslcd_open( struct inode * inode, struct file * file )
 {
-	cycle_kernel_lock();
 	return 0;
 }
 
 const struct file_operations anslcd_fops = {
-	.write	= anslcd_write,
-	.ioctl	= anslcd_ioctl,
-	.open	= anslcd_open,
+	.write		= anslcd_write,
+	.unlocked_ioctl	= anslcd_ioctl,
+	.open		= anslcd_open,
 };
 
 static struct miscdevice anslcd_dev = {
@@ -168,6 +177,7 @@ anslcd_init(void)
 	printk(KERN_DEBUG "LCD: init\n");
 #endif
 
+	mutex_lock(&anslcd_mutex);
 	anslcd_write_byte_ctrl ( 0x38 );
 	anslcd_write_byte_ctrl ( 0x0c );
 	anslcd_write_byte_ctrl ( 0x06 );
@@ -176,6 +186,7 @@ anslcd_init(void)
 	for(a=0;a<80;a++) {
 		anslcd_write_byte_data(anslcd_logo[a]);
 	}
+	mutex_unlock(&anslcd_mutex);
 	return 0;
 }