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![Thomas Gleixner](/assets/img/avatar_default.png)
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>
201 lines
3.9 KiB
C
201 lines
3.9 KiB
C
/*
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* /dev/lcd driver for Apple Network Servers.
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*/
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/fcntl.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/fs.h>
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#include <asm/uaccess.h>
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#include <asm/sections.h>
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#include <asm/prom.h>
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#include <asm/io.h>
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#include "ans-lcd.h"
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#define ANSLCD_ADDR 0xf301c000
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#define ANSLCD_CTRL_IX 0x00
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#define ANSLCD_DATA_IX 0x10
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static unsigned long anslcd_short_delay = 80;
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static unsigned long anslcd_long_delay = 3280;
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static volatile unsigned char __iomem *anslcd_ptr;
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static DEFINE_MUTEX(anslcd_mutex);
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#undef DEBUG
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static void
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anslcd_write_byte_ctrl ( unsigned char c )
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{
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#ifdef DEBUG
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printk(KERN_DEBUG "LCD: CTRL byte: %02x\n",c);
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#endif
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out_8(anslcd_ptr + ANSLCD_CTRL_IX, c);
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switch(c) {
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case 1:
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case 2:
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case 3:
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udelay(anslcd_long_delay); break;
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default: udelay(anslcd_short_delay);
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}
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}
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static void
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anslcd_write_byte_data ( unsigned char c )
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{
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out_8(anslcd_ptr + ANSLCD_DATA_IX, c);
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udelay(anslcd_short_delay);
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}
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static ssize_t
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anslcd_write( struct file * file, const char __user * buf,
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size_t count, loff_t *ppos )
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{
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const char __user *p = buf;
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int i;
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#ifdef DEBUG
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printk(KERN_DEBUG "LCD: write\n");
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#endif
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if (!access_ok(VERIFY_READ, buf, count))
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return -EFAULT;
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mutex_lock(&anslcd_mutex);
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for ( i = *ppos; count > 0; ++i, ++p, --count )
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{
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char c;
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__get_user(c, p);
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anslcd_write_byte_data( c );
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}
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mutex_unlock(&anslcd_mutex);
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*ppos = i;
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return p - buf;
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}
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static long
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anslcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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char ch, __user *temp;
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long ret = 0;
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#ifdef DEBUG
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printk(KERN_DEBUG "LCD: ioctl(%d,%d)\n",cmd,arg);
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#endif
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mutex_lock(&anslcd_mutex);
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switch ( cmd )
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{
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case ANSLCD_CLEAR:
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anslcd_write_byte_ctrl ( 0x38 );
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anslcd_write_byte_ctrl ( 0x0f );
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anslcd_write_byte_ctrl ( 0x06 );
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anslcd_write_byte_ctrl ( 0x01 );
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anslcd_write_byte_ctrl ( 0x02 );
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break;
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case ANSLCD_SENDCTRL:
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temp = (char __user *) arg;
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__get_user(ch, temp);
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for (; ch; temp++) { /* FIXME: This is ugly, but should work, as a \0 byte is not a valid command code */
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anslcd_write_byte_ctrl ( ch );
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__get_user(ch, temp);
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}
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break;
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case ANSLCD_SETSHORTDELAY:
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if (!capable(CAP_SYS_ADMIN))
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ret =-EACCES;
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else
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anslcd_short_delay=arg;
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break;
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case ANSLCD_SETLONGDELAY:
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if (!capable(CAP_SYS_ADMIN))
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ret = -EACCES;
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else
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anslcd_long_delay=arg;
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break;
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default:
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ret = -EINVAL;
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}
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mutex_unlock(&anslcd_mutex);
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return ret;
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}
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static int
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anslcd_open( struct inode * inode, struct file * file )
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{
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return 0;
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}
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const struct file_operations anslcd_fops = {
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.write = anslcd_write,
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.unlocked_ioctl = anslcd_ioctl,
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.open = anslcd_open,
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};
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static struct miscdevice anslcd_dev = {
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ANSLCD_MINOR,
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"anslcd",
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&anslcd_fops
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};
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const char anslcd_logo[] = "********************" /* Line #1 */
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"* LINUX! *" /* Line #3 */
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"* Welcome to *" /* Line #2 */
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"********************"; /* Line #4 */
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static int __init
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anslcd_init(void)
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{
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int a;
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int retval;
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struct device_node* node;
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node = of_find_node_by_name(NULL, "lcd");
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if (!node || !node->parent || strcmp(node->parent->name, "gc")) {
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of_node_put(node);
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return -ENODEV;
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}
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of_node_put(node);
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anslcd_ptr = ioremap(ANSLCD_ADDR, 0x20);
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retval = misc_register(&anslcd_dev);
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if(retval < 0){
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printk(KERN_INFO "LCD: misc_register failed\n");
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iounmap(anslcd_ptr);
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return retval;
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}
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#ifdef DEBUG
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printk(KERN_DEBUG "LCD: init\n");
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#endif
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mutex_lock(&anslcd_mutex);
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anslcd_write_byte_ctrl ( 0x38 );
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anslcd_write_byte_ctrl ( 0x0c );
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anslcd_write_byte_ctrl ( 0x06 );
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anslcd_write_byte_ctrl ( 0x01 );
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anslcd_write_byte_ctrl ( 0x02 );
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for(a=0;a<80;a++) {
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anslcd_write_byte_data(anslcd_logo[a]);
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}
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mutex_unlock(&anslcd_mutex);
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return 0;
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}
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static void __exit
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anslcd_exit(void)
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{
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misc_deregister(&anslcd_dev);
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iounmap(anslcd_ptr);
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}
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module_init(anslcd_init);
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module_exit(anslcd_exit);
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