dvb-core: kill the big kernel lock

The dvb core only uses the big kernel lock in the open
and ioctl functions, which means it can be replaced with
a dvb specific mutex. Fortunately, all the ioctl functions
go through dvb_usercopy, so we can move the serialization
in there.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: linux-media@vger.kernel.org

1 files changed, 7 insertions, 10 deletions

diff --git a/drivers/media/dvb/dvb-core/dvbdev.c b/drivers/media/dvb/dvb-core/dvbdev.c
index b915c39..28f486e 100644
--- a/drivers/media/dvb/dvb-core/dvbdev.c
+++ b/drivers/media/dvb/dvb-core/dvbdev.c
@@ -32,9 +32,9 @@
 #include <linux/fs.h>
 #include <linux/cdev.h>
 #include <linux/mutex.h>
-#include <linux/smp_lock.h>
 #include "dvbdev.h"
 
+static DEFINE_MUTEX(dvbdev_mutex);
 static int dvbdev_debug;
 
 module_param(dvbdev_debug, int, 0644);
@@ -68,7 +68,7 @@ static int dvb_device_open(struct inode *inode, struct file *file)
 {
 	struct dvb_device *dvbdev;
 
-	lock_kernel();
+	mutex_lock(&dvbdev_mutex);
 	down_read(&minor_rwsem);
 	dvbdev = dvb_minors[iminor(inode)];
 
@@ -91,12 +91,12 @@ static int dvb_device_open(struct inode *inode, struct file *file)
 		}
 		fops_put(old_fops);
 		up_read(&minor_rwsem);
-		unlock_kernel();
+		mutex_unlock(&dvbdev_mutex);
 		return err;
 	}
 fail:
 	up_read(&minor_rwsem);
-	unlock_kernel();
+	mutex_unlock(&dvbdev_mutex);
 	return -ENODEV;
 }
 
@@ -158,7 +158,6 @@ long dvb_generic_ioctl(struct file *file,
 		       unsigned int cmd, unsigned long arg)
 {
 	struct dvb_device *dvbdev = file->private_data;
-	int ret;
 
 	if (!dvbdev)
 		return -ENODEV;
@@ -166,11 +165,7 @@ long dvb_generic_ioctl(struct file *file,
 	if (!dvbdev->kernel_ioctl)
 		return -EINVAL;
 
-	lock_kernel();
-	ret = dvb_usercopy(file, cmd, arg, dvbdev->kernel_ioctl);
-	unlock_kernel();
-
-	return ret;
+	return dvb_usercopy(file, cmd, arg, dvbdev->kernel_ioctl);
 }
 EXPORT_SYMBOL(dvb_generic_ioctl);
 
@@ -421,8 +416,10 @@ int dvb_usercopy(struct file *file,
 	}
 
 	/* call driver */
+	mutex_lock(&dvbdev_mutex);
 	if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD)
 		err = -EINVAL;
+	mutex_unlock(&dvbdev_mutex);
 
 	if (err < 0)
 		goto out;