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, 13 insertions, 11 deletions

diff --git a/drivers/sbus/char/jsflash.c b/drivers/sbus/char/jsflash.c
index 4942050..13f48e2 100644
--- a/drivers/sbus/char/jsflash.c
+++ b/drivers/sbus/char/jsflash.c
@@ -27,7 +27,7 @@
  */
 
 #include <linux/module.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/miscdevice.h>
@@ -68,6 +68,8 @@
 #define JSF_PART_BITS	 2	/* 2 bits of minors to cover JSF_NPART */
 #define JSF_PART_MASK	 0x3	/* 2 bits mask */
 
+static DEFINE_MUTEX(jsf_mutex);
+
 /*
  * Access functions.
  * We could ioremap(), but it's easier this way.
@@ -225,7 +227,7 @@ static loff_t jsf_lseek(struct file * file, loff_t offset, int orig)
 {
 	loff_t ret;
 
-	lock_kernel();
+	mutex_lock(&jsf_mutex);
 	switch (orig) {
 		case 0:
 			file->f_pos = offset;
@@ -238,7 +240,7 @@ static loff_t jsf_lseek(struct file * file, loff_t offset, int orig)
 		default:
 			ret = -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&jsf_mutex);
 	return ret;
 }
 
@@ -384,18 +386,18 @@ static int jsf_ioctl_program(void __user *arg)
 
 static long jsf_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 {
-	lock_kernel();
+	mutex_lock(&jsf_mutex);
 	int error = -ENOTTY;
 	void __user *argp = (void __user *)arg;
 
 	if (!capable(CAP_SYS_ADMIN)) {
-		unlock_kernel();
+		mutex_unlock(&jsf_mutex);
 		return -EPERM;
 	}
 	switch (cmd) {
 	case JSFLASH_IDENT:
 		if (copy_to_user(argp, &jsf0.id, JSFIDSZ)) {
-			unlock_kernel();
+			mutex_unlock(&jsf_mutex);
 			return -EFAULT;
 		}
 		break;
@@ -407,7 +409,7 @@ static long jsf_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 		break;
 	}
 
-	unlock_kernel();
+	mutex_unlock(&jsf_mutex);
 	return error;
 }
 
@@ -418,17 +420,17 @@ static int jsf_mmap(struct file * file, struct vm_area_struct * vma)
 
 static int jsf_open(struct inode * inode, struct file * filp)
 {
-	lock_kernel();
+	mutex_lock(&jsf_mutex);
 	if (jsf0.base == 0) {
-		unlock_kernel();
+		mutex_unlock(&jsf_mutex);
 		return -ENXIO;
 	}
 	if (test_and_set_bit(0, (void *)&jsf0.busy) != 0) {
-		unlock_kernel();
+		mutex_unlock(&jsf_mutex);
 		return -EBUSY;
 	}
 
-	unlock_kernel();
+	mutex_unlock(&jsf_mutex);
 	return 0;	/* XXX What security? */
 }