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>
diff --git a/drivers/misc/phantom.c b/drivers/misc/phantom.c
index 75ee0d3..3712e50 100644
--- a/drivers/misc/phantom.c
+++ b/drivers/misc/phantom.c
@@ -24,7 +24,7 @@
#include <linux/slab.h>
#include <linux/phantom.h>
#include <linux/sched.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
#include <asm/atomic.h>
#include <asm/io.h>
@@ -38,6 +38,7 @@
#define PHB_RUNNING 1
#define PHB_NOT_OH 2
+static DEFINE_MUTEX(phantom_mutex);
static struct class *phantom_class;
static int phantom_major;
@@ -215,17 +216,17 @@
struct phantom_device *dev = container_of(inode->i_cdev,
struct phantom_device, cdev);
- lock_kernel();
+ mutex_lock(&phantom_mutex);
nonseekable_open(inode, file);
if (mutex_lock_interruptible(&dev->open_lock)) {
- unlock_kernel();
+ mutex_unlock(&phantom_mutex);
return -ERESTARTSYS;
}
if (dev->opened) {
mutex_unlock(&dev->open_lock);
- unlock_kernel();
+ mutex_unlock(&phantom_mutex);
return -EINVAL;
}
@@ -236,7 +237,7 @@
atomic_set(&dev->counter, 0);
dev->opened++;
mutex_unlock(&dev->open_lock);
- unlock_kernel();
+ mutex_unlock(&phantom_mutex);
return 0;
}