[PATCHv6 3/7] tap: Tap character device creation/destroy API

From: Sainath Grandhi
Date: Fri Feb 10 2017 - 19:04:43 EST


This patch provides tap device create/destroy APIs in tap.c.

Signed-off-by: Sainath Grandhi <sainath.grandhi@xxxxxxxxx>
---
drivers/net/macvtap_main.c | 30 +++++++---------------
drivers/net/tap.c | 62 ++++++++++++++++++++++++++++++++++++++--------
include/linux/if_tap.h | 3 +++
3 files changed, 63 insertions(+), 32 deletions(-)

diff --git a/drivers/net/macvtap_main.c b/drivers/net/macvtap_main.c
index 548f339..215ab7a 100644
--- a/drivers/net/macvtap_main.c
+++ b/drivers/net/macvtap_main.c
@@ -28,7 +28,6 @@
* Variables for dealing with macvtaps device numbers.
*/
static dev_t macvtap_major;
-#define MACVTAP_NUM_DEVS (1U << MINORBITS)

static const void *macvtap_net_namespace(struct device *d)
{
@@ -159,57 +158,46 @@ static struct notifier_block macvtap_notifier_block __read_mostly = {
.notifier_call = macvtap_device_event,
};

-extern struct file_operations tap_fops;
static int macvtap_init(void)
{
int err;

- err = alloc_chrdev_region(&macvtap_major, 0,
- MACVTAP_NUM_DEVS, "macvtap");
- if (err)
- goto out1;
+ err = tap_create_cdev(&macvtap_cdev, &macvtap_major, "macvtap");

- cdev_init(&macvtap_cdev, &tap_fops);
- err = cdev_add(&macvtap_cdev, macvtap_major, MACVTAP_NUM_DEVS);
if (err)
- goto out2;
+ goto out1;

err = class_register(&macvtap_class);
if (err)
- goto out3;
+ goto out2;

err = register_netdevice_notifier(&macvtap_notifier_block);
if (err)
- goto out4;
+ goto out3;

err = macvlan_link_register(&macvtap_link_ops);
if (err)
- goto out5;
+ goto out4;

return 0;

-out5:
- unregister_netdevice_notifier(&macvtap_notifier_block);
out4:
- class_unregister(&macvtap_class);
+ unregister_netdevice_notifier(&macvtap_notifier_block);
out3:
- cdev_del(&macvtap_cdev);
+ class_unregister(&macvtap_class);
out2:
- unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
+ tap_destroy_cdev(macvtap_major, &macvtap_cdev);
out1:
return err;
}
module_init(macvtap_init);

-extern struct idr minor_idr;
static void macvtap_exit(void)
{
rtnl_link_unregister(&macvtap_link_ops);
unregister_netdevice_notifier(&macvtap_notifier_block);
class_unregister(&macvtap_class);
- cdev_del(&macvtap_cdev);
- unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
- idr_destroy(&minor_idr);
+ tap_destroy_cdev(macvtap_major, &macvtap_cdev);
}
module_exit(macvtap_exit);

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 15ca2d5..04ba978 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -123,8 +123,12 @@ static struct proto tap_proto = {
};

#define TAP_NUM_DEVS (1U << MINORBITS)
-static DEFINE_MUTEX(minor_lock);
-DEFINE_IDR(minor_idr);
+struct major_info {
+ dev_t major;
+ struct idr minor_idr;
+ struct mutex minor_lock;
+ const char *device_name;
+} macvtap_major;

#define GOODCOPY_LEN 128

@@ -413,26 +417,26 @@ int tap_get_minor(struct macvlan_dev *vlan)
{
int retval = -ENOMEM;

- mutex_lock(&minor_lock);
- retval = idr_alloc(&minor_idr, vlan, 1, TAP_NUM_DEVS, GFP_KERNEL);
+ mutex_lock(&macvtap_major.minor_lock);
+ retval = idr_alloc(&macvtap_major.minor_idr, vlan, 1, TAP_NUM_DEVS, GFP_KERNEL);
if (retval >= 0) {
vlan->minor = retval;
} else if (retval == -ENOSPC) {
netdev_err(vlan->dev, "Too many tap devices\n");
retval = -EINVAL;
}
- mutex_unlock(&minor_lock);
+ mutex_unlock(&macvtap_major.minor_lock);
return retval < 0 ? retval : 0;
}

void tap_free_minor(struct macvlan_dev *vlan)
{
- mutex_lock(&minor_lock);
+ mutex_lock(&macvtap_major.minor_lock);
if (vlan->minor) {
- idr_remove(&minor_idr, vlan->minor);
+ idr_remove(&macvtap_major.minor_idr, vlan->minor);
vlan->minor = 0;
}
- mutex_unlock(&minor_lock);
+ mutex_unlock(&macvtap_major.minor_lock);
}

static struct net_device *dev_get_by_tap_minor(int minor)
@@ -440,13 +444,13 @@ static struct net_device *dev_get_by_tap_minor(int minor)
struct net_device *dev = NULL;
struct macvlan_dev *vlan;

- mutex_lock(&minor_lock);
- vlan = idr_find(&minor_idr, minor);
+ mutex_lock(&macvtap_major.minor_lock);
+ vlan = idr_find(&macvtap_major.minor_idr, minor);
if (vlan) {
dev = vlan->dev;
dev_hold(dev);
}
- mutex_unlock(&minor_lock);
+ mutex_unlock(&macvtap_major.minor_lock);
return dev;
}

@@ -1184,3 +1188,39 @@ int tap_queue_resize(struct macvlan_dev *vlan)
kfree(arrays);
return ret;
}
+
+int tap_create_cdev(struct cdev *tap_cdev,
+ dev_t *tap_major, const char *device_name)
+{
+ int err;
+
+ err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
+ if (err)
+ goto out1;
+
+ cdev_init(tap_cdev, &tap_fops);
+ err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
+ if (err)
+ goto out2;
+
+ macvtap_major.major = MAJOR(*tap_major);
+
+ idr_init(&macvtap_major.minor_idr);
+ mutex_init(&macvtap_major.minor_lock);
+
+ macvtap_major.device_name = device_name;
+
+ return 0;
+
+out2:
+ unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
+out1:
+ return err;
+}
+
+void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
+{
+ cdev_del(tap_cdev);
+ unregister_chrdev_region(major, TAP_NUM_DEVS);
+ idr_destroy(&macvtap_major.minor_idr);
+}
diff --git a/include/linux/if_tap.h b/include/linux/if_tap.h
index 97d27b8..a2dfd90 100644
--- a/include/linux/if_tap.h
+++ b/include/linux/if_tap.h
@@ -19,5 +19,8 @@ void tap_del_queues(struct net_device *dev);
int tap_get_minor(struct macvlan_dev *vlan);
void tap_free_minor(struct macvlan_dev *vlan);
int tap_queue_resize(struct macvlan_dev *vlan);
+int tap_create_cdev(struct cdev *tap_cdev,
+ dev_t *tap_major, const char *device_name);
+void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev);

#endif /*_LINUX_IF_TAP_H_*/
--
2.7.4