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, 7 insertions, 6 deletions

diff --git a/drivers/pci/hotplug/cpqphp_sysfs.c b/drivers/pci/hotplug/cpqphp_sysfs.c
index 5621532..4cb3044 100644
--- a/drivers/pci/hotplug/cpqphp_sysfs.c
+++ b/drivers/pci/hotplug/cpqphp_sysfs.c
@@ -34,10 +34,11 @@
 #include <linux/workqueue.h>
 #include <linux/pci.h>
 #include <linux/pci_hotplug.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/debugfs.h>
 #include "cpqphp.h"
 
+static DEFINE_MUTEX(cpqphp_mutex);
 static int show_ctrl (struct controller *ctrl, char *buf)
 {
 	char *out = buf;
@@ -147,7 +148,7 @@ static int open(struct inode *inode, struct file *file)
 	struct ctrl_dbg *dbg;
 	int retval = -ENOMEM;
 
-	lock_kernel();
+	mutex_lock(&cpqphp_mutex);
 	dbg = kmalloc(sizeof(*dbg), GFP_KERNEL);
 	if (!dbg)
 		goto exit;
@@ -160,7 +161,7 @@ static int open(struct inode *inode, struct file *file)
 	file->private_data = dbg;
 	retval = 0;
 exit:
-	unlock_kernel();
+	mutex_unlock(&cpqphp_mutex);
 	return retval;
 }
 
@@ -169,7 +170,7 @@ static loff_t lseek(struct file *file, loff_t off, int whence)
 	struct ctrl_dbg *dbg;
 	loff_t new = -1;
 
-	lock_kernel();
+	mutex_lock(&cpqphp_mutex);
 	dbg = file->private_data;
 
 	switch (whence) {
@@ -181,10 +182,10 @@ static loff_t lseek(struct file *file, loff_t off, int whence)
 		break;
 	}
 	if (new < 0 || new > dbg->size) {
-		unlock_kernel();
+		mutex_unlock(&cpqphp_mutex);
 		return -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&cpqphp_mutex);
 	return (file->f_pos = new);
 }