mtd: 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 <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: [e-mail]

drivers/mtd/mtdchar.c

···
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/backing-dev.h>
 #include <linux/compat.h>
 #include <linux/mount.h>
···
 #include <asm/uaccess.h>
 
 #define MTD_INODE_FS_MAGIC 0x11307854
+static DEFINE_MUTEX(mtd_mutex);
 static struct vfsmount *mtd_inode_mnt __read_mostly;
 
 /*
···
 	if ((file->f_mode & FMODE_WRITE) && (minor & 1))
 		return -EACCES;
 
-	lock_kernel();
+	mutex_lock(&mtd_mutex);
 	mtd = get_mtd_device(NULL, devnum);
 
 	if (IS_ERR(mtd)) {
···
 	file->private_data = mfi;
 
 out:
-	unlock_kernel();
+	mutex_unlock(&mtd_mutex);
 	return ret;
 } /* mtd_open */
 
···
 {
 	int ret;
 
-	lock_kernel();
+	mutex_lock(&mtd_mutex);
 	ret = mtd_ioctl(file, cmd, arg);
-	unlock_kernel();
+	mutex_unlock(&mtd_mutex);
 
 	return ret;
 }
···
 	void __user *argp = compat_ptr(arg);
 	int ret = 0;
 
-	lock_kernel();
+	mutex_lock(&mtd_mutex);
 
 	switch (cmd) {
 	case MEMWRITEOOB32:
···
 		ret = mtd_ioctl(file, cmd, (unsigned long)argp);
 	}
 
-	unlock_kernel();
+	mutex_unlock(&mtd_mutex);
 
 	return ret;
 }