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
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 @@
{
struct dvb_device *dvbdev;
- lock_kernel();
+ mutex_lock(&dvbdev_mutex);
down_read(&minor_rwsem);
dvbdev = dvb_minors[iminor(inode)];
@@ -91,12 +91,12 @@
}
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 @@
unsigned int cmd, unsigned long arg)
{
struct dvb_device *dvbdev = file->private_data;
- int ret;
if (!dvbdev)
return -ENODEV;
@@ -166,11 +165,7 @@
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 @@
}
/* call driver */
+ mutex_lock(&dvbdev_mutex);
if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD)
err = -EINVAL;
+ mutex_unlock(&dvbdev_mutex);
if (err < 0)
goto out;
