drivers: 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.

These drivers do not seem to be under active
maintainance from my brief investigation. Apologies
to those maintainers that I have missed.

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>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/char/lp.c b/drivers/char/lp.c
index 938a3a2..598d278 100644
--- a/drivers/char/lp.c
+++ b/drivers/char/lp.c
@@ -126,7 +126,7 @@
 #include <linux/device.h>
 #include <linux/wait.h>
 #include <linux/jiffies.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/compat.h>
 
 #include <linux/parport.h>
@@ -140,6 +140,7 @@
 /* if you have more than 8 printers, remember to increase LP_NO */
 #define LP_NO 8
 
+static DEFINE_MUTEX(lp_mutex);
 static struct lp_struct lp_table[LP_NO];
 
 static unsigned int lp_count = 0;
@@ -493,7 +494,7 @@ static int lp_open(struct inode * inode, struct file * file)
 	unsigned int minor = iminor(inode);
 	int ret = 0;
 
-	lock_kernel();
+	mutex_lock(&lp_mutex);
 	if (minor >= LP_NO) {
 		ret = -ENXIO;
 		goto out;
@@ -554,7 +555,7 @@ static int lp_open(struct inode * inode, struct file * file)
 	lp_release_parport (&lp_table[minor]);
 	lp_table[minor].current_mode = IEEE1284_MODE_COMPAT;
 out:
-	unlock_kernel();
+	mutex_unlock(&lp_mutex);
 	return ret;
 }
 
@@ -680,7 +681,7 @@ static long lp_ioctl(struct file *file, unsigned int cmd,
 	int ret;
 
 	minor = iminor(file->f_path.dentry->d_inode);
-	lock_kernel();
+	mutex_lock(&lp_mutex);
 	switch (cmd) {
 	case LPSETTIMEOUT:
 		if (copy_from_user(&par_timeout, (void __user *)arg,
@@ -694,7 +695,7 @@ static long lp_ioctl(struct file *file, unsigned int cmd,
 		ret = lp_do_ioctl(minor, cmd, arg, (void __user *)arg);
 		break;
 	}
-	unlock_kernel();
+	mutex_unlock(&lp_mutex);
 
 	return ret;
 }
@@ -709,7 +710,7 @@ static long lp_compat_ioctl(struct file *file, unsigned int cmd,
 	int ret;
 
 	minor = iminor(file->f_path.dentry->d_inode);
-	lock_kernel();
+	mutex_lock(&lp_mutex);
 	switch (cmd) {
 	case LPSETTIMEOUT:
 		tc = compat_ptr(arg);
@@ -730,7 +731,7 @@ static long lp_compat_ioctl(struct file *file, unsigned int cmd,
 		ret = lp_do_ioctl(minor, cmd, arg, compat_ptr(arg));
 		break;
 	}
-	unlock_kernel();
+	mutex_unlock(&lp_mutex);
 
 	return ret;
 }