mac: 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>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/macintosh/via-pmu.c b/drivers/macintosh/via-pmu.c
index 2d17e76..7b8b1de 100644
--- a/drivers/macintosh/via-pmu.c
+++ b/drivers/macintosh/via-pmu.c
@@ -18,7 +18,7 @@
  *
  */
 #include <stdarg.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
@@ -73,6 +73,7 @@
 /* How many iterations between battery polls */
 #define BATTERY_POLLING_COUNT	2
 
+static DEFINE_MUTEX(pmu_info_proc_mutex);
 static volatile unsigned char __iomem *via;
 
 /* VIA registers - spaced 0x200 bytes apart */
@@ -2078,7 +2079,7 @@ pmu_open(struct inode *inode, struct file *file)
 	pp->rb_get = pp->rb_put = 0;
 	spin_lock_init(&pp->lock);
 	init_waitqueue_head(&pp->wait);
-	lock_kernel();
+	mutex_lock(&pmu_info_proc_mutex);
 	spin_lock_irqsave(&all_pvt_lock, flags);
 #if defined(CONFIG_INPUT_ADBHID) && defined(CONFIG_PMAC_BACKLIGHT)
 	pp->backlight_locker = 0;
@@ -2086,7 +2087,7 @@ pmu_open(struct inode *inode, struct file *file)
 	list_add(&pp->list, &all_pmu_pvt);
 	spin_unlock_irqrestore(&all_pvt_lock, flags);
 	file->private_data = pp;
-	unlock_kernel();
+	mutex_unlock(&pmu_info_proc_mutex);
 	return 0;
 }
 
@@ -2343,9 +2344,9 @@ static long pmu_unlocked_ioctl(struct file *filp,
 {
 	int ret;
 
-	lock_kernel();
+	mutex_lock(&pmu_info_proc_mutex);
 	ret = pmu_ioctl(filp, cmd, arg);
-	unlock_kernel();
+	mutex_unlock(&pmu_info_proc_mutex);
 
 	return ret;
 }