[net-next,v1,1/9] net: add netdev_upper_get_next_dev(dev, iter)

This function returns the next dev in the dev->upper_dev_list after the
struct list_head **iter position, and updates *iter accordingly. Returns
NULL if there are no devices left.

v1: new patch

CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Jiri Pirko <jiri@resnulli.us>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Cong Wang <amwang@redhat.com>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
 net/core/dev.c |   25 +++++++++++++++++++++++++
 1 files changed, 25 insertions(+), 0 deletions(-)

Mon, Aug 26, 2013 at 10:32:34PM CEST, vfalico@redhat.com wrote:
>This function returns the next dev in the dev->upper_dev_list after the
>struct list_head **iter position, and updates *iter accordingly. Returns
>NULL if there are no devices left.
>
>v1: new patch
>
>CC: "David S. Miller" <davem@davemloft.net>
>CC: Eric Dumazet <edumazet@google.com>
>CC: Jiri Pirko <jiri@resnulli.us>
>CC: Alexander Duyck <alexander.h.duyck@intel.com>
>CC: Cong Wang <amwang@redhat.com>
>Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
>---
> net/core/dev.c |   25 +++++++++++++++++++++++++
> 1 files changed, 25 insertions(+), 0 deletions(-)
>
>diff --git a/net/core/dev.c b/net/core/dev.c
>index 1ed2b66..566e99a 100644
>--- a/net/core/dev.c
>+++ b/net/core/dev.c
>@@ -4477,6 +4477,31 @@ struct net_device *netdev_master_upper_dev_get(struct net_device *dev)
> }
> EXPORT_SYMBOL(netdev_master_upper_dev_get);
> 
>+/* netdev_upper_get_next_dev - Get the next dev from upper list
>+ * @dev: device
>+ * @iter: list_head ** of the current position
>+ *
>+ * Gets the next device from the dev's upper list, starting from iter
>+ * position. The caller must hold RCU read lock.
>+ */
>+struct net_device *netdev_upper_get_next_dev(struct net_device *dev,
>+					     struct list_head **iter)

		This should be probably rather named
		"netdev_upper_get_next_dev_rcu" That way it is clear
		right away. Also if you introduce non-rcu variant in
		future, you won't introduce confusion :)


>+{
>+	struct netdev_upper *upper;
>+
>+	WARN_ON_ONCE(!rcu_read_lock_held());
>+
>+	upper = list_entry_rcu((*iter)->next, struct netdev_upper, list);
>+
>+	if (&upper->list == &dev->upper_dev_list)
>+		return NULL;
>+
>+	*iter = &upper->list;
>+
>+	return upper->dev;
>+}
>+EXPORT_SYMBOL(netdev_upper_get_next_dev);
>+
> /**
>  * netdev_master_upper_dev_get_rcu - Get master upper device
>  * @dev: device
>-- 
>1.7.1
>
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On Mon, Aug 26, 2013 at 10:57:48PM +0200, Jiri Pirko wrote:
>Mon, Aug 26, 2013 at 10:32:34PM CEST, vfalico@redhat.com wrote:
...snip...
>>+struct net_device *netdev_upper_get_next_dev(struct net_device *dev,
>>+					     struct list_head **iter)
>
>		This should be probably rather named
>		"netdev_upper_get_next_dev_rcu" That way it is clear
>		right away. Also if you introduce non-rcu variant in
>		future, you won't introduce confusion :)

Agreed, it will be easier, will do in v2.
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