USB: autoconvert trivial BKL users to private mutex

All these files use the big kernel lock in a trivial
way to serialize their private file operations,
typically resulting from an earlier semi-automatic
pushdown from VFS.

None of these drivers appears to want to lock against
other code, and they all use the BKL as the top-level
lock in their file operations, meaning that there
is no lock-order inversion problem.

Consequently, we can remove the BKL completely,
replacing it with a per-file mutex in every case.
Using a scripted approach means we can avoid
typos.

file=$1
name=$2
if grep -q lock_kernel ${file} ; then
    if grep -q 'include.*linux.mutex.h' ${file} ; then
            sed -i '/include.*<linux\/smp_lock.h>/d' ${file}
    else
            sed -i 's/include.*<linux\/smp_lock.h>.*$/include <linux\/mutex.h>/g' ${file}
    fi
    sed -i ${file} \
        -e "/^#include.*linux.mutex.h/,$ {
                1,/^\(static\|int\|long\)/ {
                     /^\(static\|int\|long\)/istatic DEFINE_MUTEX(${name}_mutex);

} }"  \
    -e "s/\(un\)*lock_kernel\>[ ]*()/mutex_\1lock(\&${name}_mutex)/g" \
    -e '/[      ]*cycle_kernel_lock();/d'
else
    sed -i -e '/include.*\<smp_lock.h\>/d' ${file}  \
                -e '/cycle_kernel_lock()/d'
fi

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 8 deletions

diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c
index 7828c764b323..6ae39e3e5046 100644
--- a/drivers/usb/misc/usblcd.c
+++ b/drivers/usb/misc/usblcd.c
@@ -16,7 +16,6 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/errno.h>
 #include <linux/mutex.h>
 #include <asm/uaccess.h>
@@ -30,6 +29,7 @@
 #define IOCTL_GET_DRV_VERSION   2
 
 
+static DEFINE_MUTEX(lcd_mutex);
 static const struct usb_device_id id_table[] = {
         { .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
         { },
@@ -74,12 +74,12 @@ static int lcd_open(struct inode *inode, struct file *file)
         struct usb_interface *interface;
         int subminor, r;
 
-        lock_kernel();
+        mutex_lock(&lcd_mutex);
         subminor = iminor(inode);
 
         interface = usb_find_interface(&lcd_driver, subminor);
         if (!interface) {
-                unlock_kernel();
+                mutex_unlock(&lcd_mutex);
                 err ("USBLCD: %s - error, can't find device for minor %d",
                      __func__, subminor);
                 return -ENODEV;
@@ -89,7 +89,7 @@ static int lcd_open(struct inode *inode, struct file *file)
         dev = usb_get_intfdata(interface);
         if (!dev) {
                 mutex_unlock(&open_disc_mutex);
-                unlock_kernel();
+                mutex_unlock(&lcd_mutex);
                 return -ENODEV;
         }
 
@@ -101,13 +101,13 @@ static int lcd_open(struct inode *inode, struct file *file)
         r = usb_autopm_get_interface(interface);
         if (r < 0) {
                 kref_put(&dev->kref, lcd_delete);
-                unlock_kernel();
+                mutex_unlock(&lcd_mutex);
                 return r;
         }
 
         /* save our object in the file's private structure */
         file->private_data = dev;
-        unlock_kernel();
+        mutex_unlock(&lcd_mutex);
 
         return 0;
 }
@@ -164,14 +164,14 @@ static long lcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         
         switch (cmd) {
         case IOCTL_GET_HARD_VERSION:
-                lock_kernel();
+                mutex_lock(&lcd_mutex);
                 bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
                 sprintf(buf,"%1d%1d.%1d%1d",
                         (bcdDevice & 0xF000)>>12,
                         (bcdDevice & 0xF00)>>8,
                         (bcdDevice & 0xF0)>>4,
                         (bcdDevice & 0xF));
-                unlock_kernel();
+                mutex_unlock(&lcd_mutex);
                 if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
                         return -EFAULT;
                 break;