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, 6 insertions, 5 deletions

diff --git a/drivers/char/viotape.c b/drivers/char/viotape.c
index 42f7fa442ff8..6f954a808b65 100644
--- a/drivers/char/viotape.c
+++ b/drivers/char/viotape.c
@@ -46,7 +46,7 @@
 #include <linux/completion.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/slab.h>
 
 #include <asm/uaccess.h>
@@ -64,6 +64,7 @@
 #define VIOTAPE_KERN_WARN       KERN_WARNING "viotape: "
 #define VIOTAPE_KERN_INFO       KERN_INFO "viotape: "
 
+static DEFINE_MUTEX(proc_viotape_mutex);
 static int viotape_numdev;
 
 /*
@@ -684,9 +685,9 @@ static long viotap_unlocked_ioctl(struct file *file,
 {
         long rc;
 
-        lock_kernel();
+        mutex_lock(&proc_viotape_mutex);
         rc = viotap_ioctl(file->f_path.dentry->d_inode, file, cmd, arg);
-        unlock_kernel();
+        mutex_unlock(&proc_viotape_mutex);
         return rc;
 }
 
@@ -700,7 +701,7 @@ static int viotap_open(struct inode *inode, struct file *file)
         if (op == NULL)
                 return -ENOMEM;
 
-        lock_kernel();
+        mutex_lock(&proc_viotape_mutex);
         get_dev_info(file->f_path.dentry->d_inode, &devi);
 
         /* Note: We currently only support one mode! */
@@ -731,7 +732,7 @@ static int viotap_open(struct inode *inode, struct file *file)
 
 free_op:
         free_op_struct(op);
-        unlock_kernel();
+        mutex_unlock(&proc_viotape_mutex);
         return ret;
 }