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, 4 insertions, 4 deletions

diff --git a/drivers/char/dtlk.c b/drivers/char/dtlk.c
index e3859d4eaead..8dd040a945d4 100644
--- a/drivers/char/dtlk.c
+++ b/drivers/char/dtlk.c
@@ -57,7 +57,7 @@
 #include <linux/ioport.h>       /* for request_region */
 #include <linux/delay.h>        /* for loops_per_jiffy */
 #include <linux/sched.h>
-#include <linux/smp_lock.h>     /* cycle_kernel_lock() */
+#include <linux/mutex.h>
 #include <asm/io.h>             /* for inb_p, outb_p, inb, outb, etc. */
 #include <asm/uaccess.h>        /* for get_user, etc. */
 #include <linux/wait.h>         /* for wait_queue */
@@ -73,6 +73,7 @@
 #define TRACE_RET ((void) 0)
 #endif                          /* TRACING */
 
+static DEFINE_MUTEX(dtlk_mutex);
 static void dtlk_timer_tick(unsigned long data);
 
 static int dtlk_major;
@@ -275,9 +276,9 @@ static long dtlk_ioctl(struct file *file,
         switch (cmd) {
 
         case DTLK_INTERROGATE:
-                lock_kernel();
+                mutex_lock(&dtlk_mutex);
                 sp = dtlk_interrogate();
-                unlock_kernel();
+                mutex_unlock(&dtlk_mutex);
                 if (copy_to_user(argp, sp, sizeof(struct dtlk_settings)))
                         return -EINVAL;
                 return 0;
@@ -296,7 +297,6 @@ static int dtlk_open(struct inode *inode, struct file *file)
 {
         TRACE_TEXT("(dtlk_open");
 
-        cycle_kernel_lock();
         nonseekable_open(inode, file);
         switch (iminor(inode)) {
         case DTLK_MINOR: