Re: [patch net-next 01/16] net: introduce upper device lists

Jiri Pirko
2012-08-14T12:24:33Z

Mon, Aug 13, 2012 at 07:52:17PM CEST, fbl@redhat.com wrote:
>On Mon, 13 Aug 2012 17:27:00 +0200
>Jiri Pirko <jiri@resnulli.us> wrote:
>
>> This lists are supposed to serve for storing pointers to all upper devices.
>> Eventually it will replace dev->master pointer which is used for
>> bonding, bridge, team but it cannot be used for vlan, macvlan where
>> there might be multiple "masters" present.
>>
>> New upper device list resolves this limitation. Also, the information
>> stored in lists is used for preventing looping setups like
>> "bond->somethingelse->samebond"
>>
>> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
>> ---
>> include/linux/netdevice.h | 14 +++
>> net/core/dev.c | 232 ++++++++++++++++++++++++++++++++++++++++++++-
>> 2 files changed, 244 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index a9db4f3..e7a07f8 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -1173,6 +1173,8 @@ struct net_device {
>> * which this device is member of.
>> */
>>
>> + struct list_head upper_dev_list; /* List of upper devices */
>> +
>> /* Interface address info used in eth_type_trans() */
>> unsigned char *dev_addr; /* hw address, (before bcast
>> because most packets are
>> @@ -2611,6 +2613,18 @@ extern int netdev_max_backlog;
>> extern int netdev_tstamp_prequeue;
>> extern int weight_p;
>> extern int bpf_jit_enable;
>> +
>> +extern bool netdev_has_upper_dev(struct net_device *dev,
>> + struct net_device *upper_dev);
>> +extern bool netdev_has_any_upper_dev(struct net_device *dev);
>> +extern struct net_device *netdev_unique_upper_dev_get(struct net_device *dev);
>> +extern struct net_device *netdev_unique_upper_dev_get_rcu(struct net_device *dev);
>> +extern int netdev_upper_dev_link(struct net_device *dev,
>> + struct net_device *upper_dev);
>> +extern int netdev_unique_upper_dev_link(struct net_device *dev,
>> + struct net_device *upper_dev);
>> +extern void netdev_upper_dev_unlink(struct net_device *dev,
>> + struct net_device *upper_dev);
>> extern int netdev_set_master(struct net_device *dev, struct net_device *master);
>> extern int netdev_set_bond_master(struct net_device *dev,
>> struct net_device *master);
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index 1f06df8..68db1ac 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -4425,6 +4425,229 @@ static int __init dev_proc_init(void)
>> #endif /* CONFIG_PROC_FS */
>>
>>
>> +struct netdev_upper {
>> + struct net_device *dev;
>> + bool unique;
>
>unique is quite confusing here. I see that it is possible to have
>one unique and many non-unique linked in the list, so maybe rename
>to 'main_dev', 'master' or 'principal'...
>
>
>> + struct list_head list;
>> + struct rcu_head rcu;
>> +};
>> +
>> +static bool __netdev_has_upper_dev(struct net_device *dev,
>> + struct net_device *upper_dev,
>> + bool deep)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + list_for_each_entry(upper, &dev->upper_dev_list, list) {
>> + if (upper->dev == upper_dev)
>> + return true;
>> + if (deep && __netdev_has_upper_dev(upper->dev, upper_dev, deep))
>> + return true;
>> + }
>> + return false;
>> +}
>> +
>> +static struct netdev_upper *__netdev_find_upper(struct net_device *dev,
>> + struct net_device *upper_dev)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + list_for_each_entry(upper, &dev->upper_dev_list, list) {
>> + if (upper->dev == upper_dev)
>> + return upper;
>> + }
>> + return NULL;
>> +}
>> +
>> +/**
>> + * netdev_has_upper_dev - Check if device is linked to an upper device
>> + * @dev: device
>> + * @upper_dev: upper device to check
>> + *
>> + * Find out if a device is linked to specified upper device and return true
>> + * in case it is. The caller must hold the RTNL semaphore.
>> + */
>> +bool netdev_has_upper_dev(struct net_device *dev,
>> + struct net_device *upper_dev)
>> +{
>> + ASSERT_RTNL();
>> +
>> + return __netdev_has_upper_dev(dev, upper_dev, false);
>> +}
>> +EXPORT_SYMBOL(netdev_has_upper_dev);
>> +
>> +/**
>> + * netdev_has_any_upper_dev - Check if device is linked to some device
>> + * @dev: device
>> + *
>> + * Find out if a device is linked to an upper device and return true in case
>> + * it is. The caller must hold the RTNL semaphore.
>> + */
>> +bool netdev_has_any_upper_dev(struct net_device *dev)
>> +{
>> + ASSERT_RTNL();
>> +
>> + return !list_empty(&dev->upper_dev_list);
>> +}
>> +EXPORT_SYMBOL(netdev_has_any_upper_dev);
>> +
>> +/**
>> + * netdev_unique_upper_dev_get - Get unique upper device
>> + * @dev: device
>> + *
>> + * Find a unique upper device and return pointer to it or NULL in case
>> + * it's not there. The caller must hold the RTNL semaphore.
>> + */
>> +struct net_device *netdev_unique_upper_dev_get(struct net_device *dev)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + ASSERT_RTNL();
>> +
>> + if (list_empty(&dev->upper_dev_list))
>> + return NULL;
>> +
>> + upper = list_first_entry(&dev->upper_dev_list,
>> + struct netdev_upper, list);
>> + if (likely(upper->unique))
>> + return upper->dev;
>> + return NULL;
>> +}
>> +EXPORT_SYMBOL(netdev_unique_upper_dev_get);
>> +
>> +/**
>> + * netdev_unique_upper_dev_get_rcu - Get unique upper device
>> + * @dev: device
>> + *
>> + * Find a unique upper device and return pointer to it or NULL in case
>> + * it's not there. The caller must hold the RCU read lock.
>> + */
>> +struct net_device *netdev_unique_upper_dev_get_rcu(struct net_device *dev)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + upper = list_first_or_null_rcu(&dev->upper_dev_list,
>> + struct netdev_upper, list);
>> + if (likely(upper->unique))
>
>It will oopses here if 'upper' is NULL (i.e. no upper devices).

Fixed

>
>
>> + return upper->dev;
>> + return NULL;
>> +}
>> +EXPORT_SYMBOL(netdev_unique_upper_dev_get_rcu);
>> +
>> +static int __netdev_upper_dev_link(struct net_device *dev,
>> + struct net_device *upper_dev, bool unique)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + ASSERT_RTNL();
>> +
>> + if (dev == upper_dev)
>> + return -EBUSY;
>> + /*
>> + * To prevent loops, check if dev is not upper device to upper_dev.
>> + */
>> + if (__netdev_has_upper_dev(upper_dev, dev, true))
>> + return -EBUSY;
>> +
>> + if (__netdev_find_upper(dev, upper_dev))
>> + return -EEXIST;
>
>__netdev_has_upper_dev() can go all the way up finding the device and
>the __netdev_find_upper() just check the first level.

I do not think this ordering is somewhat inportant.

>
>I think it would be better to use:
>__netdev_find_upper_dev(,,deep=true/false)
>__netdev_has_upper(,)
>
>thanks,
>fbl
>
>> + if (unique && netdev_unique_upper_dev_get(dev))
>> + return -EBUSY;
>> +
>> + upper = kmalloc(sizeof(*upper), GFP_KERNEL);
>> + if (!upper)
>> + return -ENOMEM;
>> +
>> + upper->dev = upper_dev;
>> + upper->unique = unique;
>> +
>> + /*
>> + * Ensure that unique upper link is always the first item in the list.
>> + */
>> + if (unique)
>> + list_add_rcu(&upper->list, &dev->upper_dev_list);
>> + else
>> + list_add_tail_rcu(&upper->list, &dev->upper_dev_list);
>> + dev_hold(upper_dev);
>> +
>> + return 0;
>> +}
>> +/**
>> + * netdev_upper_dev_link - Add a link to the upper device
>> + * @dev: device
>> + * @upper_dev: new upper device
>> + *
>> + * Adds a link to device which is upper to this one. The caller must hold
>> + * the RTNL semaphore. On a failure a negative errno code is returned.
>> + * On success the reference counts are adjusted and the function
>> + * returns zero.
>> + */
>> +int netdev_upper_dev_link(struct net_device *dev,
>> + struct net_device *upper_dev)
>> +{
>> + return __netdev_upper_dev_link(dev, upper_dev, false);
>> +}
>> +EXPORT_SYMBOL(netdev_upper_dev_link);
>> +
>> +/**
>> + * netdev_unique_upper_dev_link - Add a unique link to the upper device
>> + * @dev: device
>> + * @upper_dev: new upper device
>> + *
>> + * Adds a link to device which is upper to this one. In this case, only
>> + * one unique upper device can be linked, although other non-unique devices
>> + * might be linked as well. The caller must hold the RTNL semaphore.
>> + * On a failure a negative errno code is returned. On success the reference
>> + * counts are adjusted and the function returns zero.
>> + */
>> +int netdev_unique_upper_dev_link(struct net_device *dev,
>> + struct net_device *upper_dev)
>> +{
>> + return __netdev_upper_dev_link(dev, upper_dev, true);
>> +}
>> +EXPORT_SYMBOL(netdev_unique_upper_dev_link);
>> +
>> +/**
>> + * netdev_upper_free_rcu - Frees a upper device list item via the RCU pointer
>> + * @entry: the entry's RCU field
>> + *
>> + * This function is designed to be used as a callback to the call_rcu()
>> + * function so that the memory allocated to the netdev upper device list item
>> + * can be released safely.
>> + */
>> +static void netdev_upper_free_rcu(struct rcu_head *entry)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + upper = container_of(entry, struct netdev_upper, rcu);
>> + kfree(upper);
>> +}
>> +
>> +/**
>> + * netdev_upper_dev_unlink - Removes a link to upper device
>> + * @dev: device
>> + * @upper_dev: new upper device
>> + *
>> + * Removes a link to device which is upper to this one. The caller must hold
>> + * the RTNL semaphore.
>> + */
>> +void netdev_upper_dev_unlink(struct net_device *dev,
>> + struct net_device *upper_dev)
>> +{
>> + struct netdev_upper *upper;
>> +
>> + ASSERT_RTNL();
>> +
>> + upper = __netdev_find_upper(dev, upper_dev);
>> + if (!upper)
>> + return;
>> + list_del_rcu(&upper->list);
>> + dev_put(upper_dev);
>> + call_rcu(&upper->rcu, netdev_upper_free_rcu);
>> +}
>> +EXPORT_SYMBOL(netdev_upper_dev_unlink);
>> +
>> /**
>> * netdev_set_master - set up master pointer
>> * @slave: slave device
>> @@ -4438,19 +4661,23 @@ static int __init dev_proc_init(void)
>> int netdev_set_master(struct net_device *slave, struct net_device *master)
>> {
>> struct net_device *old = slave->master;
>> + int err;
>>
>> ASSERT_RTNL();
>>
>> if (master) {
>> if (old)
>> return -EBUSY;
>> - dev_hold(master);
>> + err = netdev_unique_upper_dev_link(slave, master);
>> + if (err)
>> + return err;
>> }
>>
>> slave->master = master;
>>
>> if (old)
>> - dev_put(old);
>> + netdev_upper_dev_unlink(slave, master);
>> +
>> return 0;
>> }
>> EXPORT_SYMBOL(netdev_set_master);
>> @@ -5999,6 +6226,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
>> INIT_LIST_HEAD(&dev->napi_list);
>> INIT_LIST_HEAD(&dev->unreg_list);
>> INIT_LIST_HEAD(&dev->link_watch_list);
>> + INIT_LIST_HEAD(&dev->upper_dev_list);
>> dev->priv_flags = IFF_XMIT_DST_RELEASE;
>> setup(dev);
>>
>