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

4 files changed, 11 insertions, 40 deletions

diff --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c
index 0042306ea11b..2de13b04b09d 100644
--- a/drivers/media/dvb/dvb-core/dmxdev.c
+++ b/drivers/media/dvb/dvb-core/dmxdev.c
@@ -25,7 +25,6 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/module.h>
-#include <linux/smp_lock.h>
 #include <linux/poll.h>
 #include <linux/ioctl.h>
 #include <linux/wait.h>
@@ -1088,13 +1087,7 @@ static int dvb_demux_do_ioctl(struct file *file,
 static long dvb_demux_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
 {
-        int ret;
-
-        lock_kernel();
-        ret = dvb_usercopy(file, cmd, arg, dvb_demux_do_ioctl);
-        unlock_kernel();
-
-        return ret;
+        return dvb_usercopy(file, cmd, arg, dvb_demux_do_ioctl);
 }
 
 static unsigned int dvb_demux_poll(struct file *file, poll_table *wait)
@@ -1186,13 +1179,7 @@ static int dvb_dvr_do_ioctl(struct file *file,
 static long dvb_dvr_ioctl(struct file *file,
                          unsigned int cmd, unsigned long arg)
 {
-        int ret;
-
-        lock_kernel();
-        ret = dvb_usercopy(file, cmd, arg, dvb_dvr_do_ioctl);
-        unlock_kernel();
-
-        return ret;
+        return dvb_usercopy(file, cmd, arg, dvb_dvr_do_ioctl);
 }
 
 static unsigned int dvb_dvr_poll(struct file *file, poll_table *wait)
diff --git a/drivers/media/dvb/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
index cb97e6b85432..1723a984a522 100644
--- a/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
+++ b/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
@@ -1259,13 +1259,7 @@ static int dvb_ca_en50221_io_do_ioctl(struct file *file,
 static long dvb_ca_en50221_io_ioctl(struct file *file,
                                     unsigned int cmd, unsigned long arg)
 {
-        int ret;
-
-        lock_kernel();
-        ret = dvb_usercopy(file, cmd, arg, dvb_ca_en50221_io_do_ioctl);
-        unlock_kernel();
-
-        return ret;
+        return dvb_usercopy(file, cmd, arg, dvb_ca_en50221_io_do_ioctl);
 }
 
 
diff --git a/drivers/media/dvb/dvb-core/dvb_net.c b/drivers/media/dvb/dvb-core/dvb_net.c
index 6c3a8a06ccab..a08032284cbf 100644
--- a/drivers/media/dvb/dvb-core/dvb_net.c
+++ b/drivers/media/dvb/dvb-core/dvb_net.c
@@ -59,7 +59,6 @@
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/dvb/net.h>
-#include <linux/smp_lock.h>
 #include <linux/uio.h>
 #include <asm/uaccess.h>
 #include <linux/crc32.h>
@@ -1445,13 +1444,7 @@ static int dvb_net_do_ioctl(struct file *file,
 static long dvb_net_ioctl(struct file *file,
               unsigned int cmd, unsigned long arg)
 {
-        int ret;
-
-        lock_kernel();
-        ret = dvb_usercopy(file, cmd, arg, dvb_net_do_ioctl);
-        unlock_kernel();
-
-        return ret;
+        return dvb_usercopy(file, cmd, arg, dvb_net_do_ioctl);
 }
 
 static int dvb_net_close(struct inode *inode, struct file *file)
diff --git a/drivers/media/dvb/dvb-core/dvbdev.c b/drivers/media/dvb/dvb-core/dvbdev.c
index b915c39d782f..28f486edcaf0 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;