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/apm-emulation.c b/drivers/char/apm-emulation.c
index 033e150..6a420ba 100644
--- a/drivers/char/apm-emulation.c
+++ b/drivers/char/apm-emulation.c
@@ -13,7 +13,7 @@
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/miscdevice.h>
@@ -126,6 +126,7 @@
/*
* Local variables
*/
+static DEFINE_MUTEX(apm_mutex);
static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
static int apm_disabled;
@@ -274,7 +275,7 @@
if (!as->suser || !as->writer)
return -EPERM;
- lock_kernel();
+ mutex_lock(&apm_mutex);
switch (cmd) {
case APM_IOC_SUSPEND:
mutex_lock(&state_lock);
@@ -335,7 +336,7 @@
mutex_unlock(&state_lock);
break;
}
- unlock_kernel();
+ mutex_unlock(&apm_mutex);
return err;
}
@@ -370,7 +371,7 @@
{
struct apm_user *as;
- lock_kernel();
+ mutex_lock(&apm_mutex);
as = kzalloc(sizeof(*as), GFP_KERNEL);
if (as) {
/*
@@ -390,7 +391,7 @@
filp->private_data = as;
}
- unlock_kernel();
+ mutex_unlock(&apm_mutex);
return as ? 0 : -ENOMEM;
}