sbus: 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: David S. Miller <davem@davemloft.net>
diff --git a/drivers/sbus/char/uctrl.c b/drivers/sbus/char/uctrl.c
index 5f25366..079da4c 100644
--- a/drivers/sbus/char/uctrl.c
+++ b/drivers/sbus/char/uctrl.c
@@ -9,7 +9,7 @@
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
@@ -72,6 +72,7 @@
#define UCTRL_STAT_RXNE_STA 0x04 /* receive FIFO not empty status */
#define UCTRL_STAT_RXO_STA 0x08 /* receive FIFO overflow status */
+static DEFINE_MUTEX(uctrl_mutex);
static const char *uctrl_extstatus[16] = {
"main power available",
"internal battery attached",
@@ -210,10 +211,10 @@
static int
uctrl_open(struct inode *inode, struct file *file)
{
- lock_kernel();
+ mutex_lock(&uctrl_mutex);
uctrl_get_event_status(global_driver);
uctrl_get_external_status(global_driver);
- unlock_kernel();
+ mutex_unlock(&uctrl_mutex);
return 0;
}