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/nvram.c b/drivers/char/nvram.c
index 66d2917..166f1e7 100644
--- a/drivers/char/nvram.c
+++ b/drivers/char/nvram.c
@@ -109,10 +109,11 @@
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/uaccess.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
#include <asm/system.h>
+static DEFINE_MUTEX(nvram_mutex);
static DEFINE_SPINLOCK(nvram_state_lock);
static int nvram_open_cnt; /* #times opened */
static int nvram_open_mode; /* special open modes */
@@ -308,7 +309,7 @@
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
- lock_kernel();
+ mutex_lock(&nvram_mutex);
spin_lock_irq(&rtc_lock);
for (i = 0; i < NVRAM_BYTES; ++i)
@@ -316,7 +317,7 @@
__nvram_set_checksum();
spin_unlock_irq(&rtc_lock);
- unlock_kernel();
+ mutex_unlock(&nvram_mutex);
return 0;
case NVRAM_SETCKS:
@@ -325,11 +326,11 @@
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
- lock_kernel();
+ mutex_lock(&nvram_mutex);
spin_lock_irq(&rtc_lock);
__nvram_set_checksum();
spin_unlock_irq(&rtc_lock);
- unlock_kernel();
+ mutex_unlock(&nvram_mutex);
return 0;
default: