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/char/dtlk.c b/drivers/char/dtlk.c
index e3859d4..8dd040a 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 @@
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 @@
{
TRACE_TEXT("(dtlk_open");
- cycle_kernel_lock();
nonseekable_open(inode, file);
switch (iminor(inode)) {
case DTLK_MINOR: