Re: [PATCHv2 5/7] TAP: Extending tap device create/destroy APIs

From: Andy Shevchenko
Date: Tue Jan 17 2017 - 20:03:37 EST

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In reply to: Sainath Grandhi: "[PATCHv2 5/7] TAP: Extending tap device create/destroy APIs"
Next in thread: Sainath Grandhi: "[PATCHv2 4/7] TAP: Abstract type of virtual interface from tap implementation"
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On Wed, Jan 18, 2017 at 2:03 AM, Sainath Grandhi
<sainath.grandhi@xxxxxxxxx> wrote:
> Extending tap APIs get/free_minor and create/destroy_cdev to handle more than one
> type of virtual interface.
>

Yes, looks better now.

FWIW:
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

> Signed-off-by: Sainath Grandhi <sainath.grandhi@xxxxxxxxx>
> ---
> drivers/net/macvtap_main.c | 6 +--
> drivers/net/tap.c | 98 +++++++++++++++++++++++++++++++++++-----------
> include/linux/if_tap.h | 4 +-
> 3 files changed, 80 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/net/macvtap_main.c b/drivers/net/macvtap_main.c
> index 6326a82..3f047b4 100644
> --- a/drivers/net/macvtap_main.c
> +++ b/drivers/net/macvtap_main.c
> @@ -160,7 +160,7 @@ static int macvtap_device_event(struct notifier_block *unused,
> * been registered but before register_netdevice has
> * finished running.
> */
> - err = tap_get_minor(&vlantap->tap);
> + err = tap_get_minor(macvtap_major, &vlantap->tap);
> if (err)
> return notifier_from_errno(err);
>
> @@ -168,7 +168,7 @@ static int macvtap_device_event(struct notifier_block *unused,
> classdev = device_create(&macvtap_class, &dev->dev, devt,
> dev, tap_name);
> if (IS_ERR(classdev)) {
> - tap_free_minor(&vlantap->tap);
> + tap_free_minor(macvtap_major, &vlantap->tap);
> return notifier_from_errno(PTR_ERR(classdev));
> }
> err = sysfs_create_link(&dev->dev.kobj, &classdev->kobj,
> @@ -183,7 +183,7 @@ static int macvtap_device_event(struct notifier_block *unused,
> sysfs_remove_link(&dev->dev.kobj, tap_name);
> devt = MKDEV(MAJOR(macvtap_major), vlantap->tap.minor);
> device_destroy(&macvtap_class, devt);
> - tap_free_minor(&vlantap->tap);
> + tap_free_minor(macvtap_major, &vlantap->tap);
> break;
> case NETDEV_CHANGE_TX_QUEUE_LEN:
> if (tap_queue_resize(&vlantap->tap))
> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> index 43d9d54..7f38dbe 100644
> --- a/drivers/net/tap.c
> +++ b/drivers/net/tap.c
> @@ -99,12 +99,16 @@ static struct proto tap_proto = {
> };
>
> #define TAP_NUM_DEVS (1U << MINORBITS)
> +
> +static LIST_HEAD(major_list);
> +
> struct major_info {
> dev_t major;
> struct idr minor_idr;
> struct mutex minor_lock;
> const char *device_name;
> -} macvtap_major;
> + struct list_head next;
> +};
>
> #define GOODCOPY_LEN 128
>
> @@ -385,44 +389,73 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
> return RX_HANDLER_CONSUMED;
> }
>
> -int tap_get_minor(struct tap_dev *tap)
> +static struct major_info *tap_get_major(int major)
> +{
> + struct major_info *tap_major, *tmp;
> +
> + list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
> + if (tap_major->major == major) {
> + return tap_major;
> + }
> + }
> +
> + return NULL;
> +}
> +
> +int tap_get_minor(dev_t major, struct tap_dev *tap)
> {
> int retval = -ENOMEM;
> + struct major_info *tap_major;
> +
> + tap_major = tap_get_major(MAJOR(major));
> + if (!tap_major)
> + return -EINVAL;
>
> - mutex_lock(&macvtap_major.minor_lock);
> - retval = idr_alloc(&macvtap_major.minor_idr, tap, 1, TAP_NUM_DEVS, GFP_KERNEL);
> + mutex_lock(&tap_major->minor_lock);
> + retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_KERNEL);
> if (retval >= 0) {
> tap->minor = retval;
> } else if (retval == -ENOSPC) {
> netdev_err(tap->dev, "Too many tap devices\n");
> retval = -EINVAL;
> }
> - mutex_unlock(&macvtap_major.minor_lock);
> + mutex_unlock(&tap_major->minor_lock);
> return retval < 0 ? retval : 0;
> }
>
> -void tap_free_minor(struct tap_dev *tap)
> +void tap_free_minor(dev_t major, struct tap_dev *tap)
> {
> - mutex_lock(&macvtap_major.minor_lock);
> + struct major_info *tap_major;
> +
> + tap_major = tap_get_major(MAJOR(major));
> + if (!tap_major)
> + return;
> +
> + mutex_lock(&tap_major->minor_lock);
> if (tap->minor) {
> - idr_remove(&macvtap_major.minor_idr, tap->minor);
> + idr_remove(&tap_major->minor_idr, tap->minor);
> tap->minor = 0;
> }
> - mutex_unlock(&macvtap_major.minor_lock);
> + mutex_unlock(&tap_major->minor_lock);
> }
>
> -static struct tap_dev *dev_get_by_tap_minor(int minor)
> +static struct tap_dev *dev_get_by_tap_file(int major, int minor)
> {
> struct net_device *dev = NULL;
> struct tap_dev *tap;
> + struct major_info *tap_major;
> +
> + tap_major = tap_get_major(major);
> + if (!tap_major)
> + return NULL;
>
> - mutex_lock(&macvtap_major.minor_lock);
> - tap = idr_find(&macvtap_major.minor_idr, minor);
> + mutex_lock(&tap_major->minor_lock);
> + tap = idr_find(&tap_major->minor_idr, minor);
> if (tap) {
> dev = tap->dev;
> dev_hold(dev);
> }
> - mutex_unlock(&macvtap_major.minor_lock);
> + mutex_unlock(&tap_major->minor_lock);
> return tap;
> }
>
> @@ -454,7 +487,7 @@ static int tap_open(struct inode *inode, struct file *file)
> int err = -ENODEV;
>
> rtnl_lock();
> - tap = dev_get_by_tap_minor(iminor(inode));
> + tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
> if (!tap)
> goto err;
>
> @@ -1161,6 +1194,26 @@ int tap_queue_resize(struct tap_dev *tap)
> return ret;
> }
>
> +static int tap_list_add(dev_t major, const char *device_name)
> +{
> + struct major_info *tap_major;
> + int err = 0;
> +
> + tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
> + if (!tap_major)
> + return -ENOMEM;
> +
> + tap_major->major = MAJOR(major);
> +
> + idr_init(&tap_major->minor_idr);
> + mutex_init(&tap_major->minor_lock);
> +
> + tap_major->device_name = device_name;
> +
> + list_add_tail(&tap_major->next, &major_list);
> + return err;
> +}
> +
> int tap_create_cdev(struct cdev *tap_cdev,
> dev_t *tap_major, const char *device_name)
> {
> @@ -1176,14 +1229,7 @@ int tap_create_cdev(struct cdev *tap_cdev,
> 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 err;
> + return tap_list_add(*tap_major, device_name);
>
> out2:
> unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
> @@ -1193,7 +1239,13 @@ int tap_create_cdev(struct cdev *tap_cdev,
>
> void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
> {
> + struct major_info *tap_major;
> +
> + tap_major = tap_get_major(MAJOR(major));
> + if (!tap_major)
> + return;
> +
> cdev_del(tap_cdev);
> unregister_chrdev_region(major, TAP_NUM_DEVS);
> - idr_destroy(&macvtap_major.minor_idr);
> + idr_destroy(&tap_major->minor_idr);
> }
> diff --git a/include/linux/if_tap.h b/include/linux/if_tap.h
> index 75031e5..362e71c 100644
> --- a/include/linux/if_tap.h
> +++ b/include/linux/if_tap.h
> @@ -65,8 +65,8 @@ struct tap_queue {
>
> rx_handler_result_t tap_handle_frame(struct sk_buff **pskb);
> void tap_del_queues(struct tap_dev *tap);
> -int tap_get_minor(struct tap_dev *tap);
> -void tap_free_minor(struct tap_dev *tap);
> +int tap_get_minor(dev_t major, struct tap_dev *tap);
> +void tap_free_minor(dev_t major, struct tap_dev *tap);
> int tap_queue_resize(struct tap_dev *tap);
> int tap_create_cdev(struct cdev *tap_cdev,
> dev_t *tap_major, const char *device_name);
> --
> 2.7.4
>

--
With Best Regards,
Andy Shevchenko

Next message: Shivappa Vikas: "Re: [PATCH 7/8] x86/intel_rdt/mba: Add schemata file support for MBA"
Previous message: Chen-Yu Tsai: "[PATCH] ARM: dts: sun6i: sina31s: Enable USB OTG controller in peripheral mode"
In reply to: Sainath Grandhi: "[PATCHv2 5/7] TAP: Extending tap device create/destroy APIs"
Next in thread: Sainath Grandhi: "[PATCHv2 4/7] TAP: Abstract type of virtual interface from tap implementation"
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