Staging: 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 <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/staging/vme/devices/vme_user.c b/drivers/staging/vme/devices/vme_user.c
index 326991c7d47b..8f77bd24630c 100644
--- a/drivers/staging/vme/devices/vme_user.c
+++ b/drivers/staging/vme/devices/vme_user.c
@@ -31,7 +31,7 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/syscalls.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/types.h>
 
 #include <linux/io.h>
@@ -40,6 +40,7 @@
 #include "../vme.h"
 #include "vme_user.h"
 
+static DEFINE_MUTEX(vme_user_mutex);
 static char driver_name[] = "vme_user";
 
 static int bus[USER_BUS_MAX];
@@ -559,9 +560,9 @@ vme_user_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	int ret;
 
-	lock_kernel();
+	mutex_lock(&vme_user_mutex);
 	ret = vme_user_ioctl(file->f_path.dentry->d_inode, file, cmd, arg);
-	unlock_kernel();
+	mutex_unlock(&vme_user_mutex);
 
 	return ret;
 }