Commit 95fdac73 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20091010153349.966159859@linutronix.de>
Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 9e8ab74d

drivers/macintosh/ans-lcd.c

+28 −17
Original line number Diff line number Diff line
@@ -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:
@@ -93,7 +98,7 @@ 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);
@@ -101,32 +106,36 @@ anslcd_ioctl( struct inode * inode, struct file * file, 
			anslcd_write_byte_ctrl ( ch );

			__get_user(ch, temp);

		}

		return 0;

		break;

	case ANSLCD_SETSHORTDELAY:

		if (!capable(CAP_SYS_ADMIN))

			return -EACCES;

			ret =-EACCES;

		else

			anslcd_short_delay=arg;

		return 0;

		break;

	case ANSLCD_SETLONGDELAY:

		if (!capable(CAP_SYS_ADMIN))

			return -EACCES;

			ret = -EACCES;

		else

			anslcd_long_delay=arg;

		return 0;

		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,

	.unlocked_ioctl	= anslcd_ioctl,

	.open		= anslcd_open,

};
@@ -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;

}

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