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net: add function to retrieve original skb device using NAPI ID 

Since commit b68581778c ("net: Make skb->skb_iif always track
skb->dev") skbs don't have the original index of the interface which
received the packet. This information is now needed for a new control
message related to hardware timestamping.

Instead of adding a new field to skb, we can find the device by the NAPI
ID if it is available, i.e. CONFIG_NET_RX_BUSY_POLL is enabled and the
driver is using NAPI. Add dev_get_by_napi_id() and also skb_napi_id() to
hide the CONFIG_NET_RX_BUSY_POLL ifdef.

CC: Richard Cochran <richardcochran@gmail.com>
Suggested-by: Willem de Bruijn <willemb@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Miroslav Lichvar 2017-05-19 17:52:37 +02:00 committed by David S. Miller
parent e341257548
commit 90b602f803
3 changed files with 36 additions and 0 deletions
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1
include/linux/netdevice.h
View File

@ -2456,6 +2456,7 @@ static inline int dev_recursion_level(void)
struct net_device *dev_get_by_index(struct net *net, int ifindex);
struct net_device *__dev_get_by_index(struct net *net, int ifindex);
struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
struct net_device *dev_get_by_napi_id(unsigned int napi_id);
int netdev_get_name(struct net *net, char *name, int ifindex);
int dev_restart(struct net_device *dev);
int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb);

9
include/linux/skbuff.h
View File

@ -858,6 +858,15 @@ static inline bool skb_pkt_type_ok(u32 ptype)
return ptype <= PACKET_OTHERHOST;
}
static inline unsigned int skb_napi_id(const struct sk_buff *skb)
{
#ifdef CONFIG_NET_RX_BUSY_POLL
return skb->napi_id;
#else
return 0;
#endif
}
void kfree_skb(struct sk_buff *skb);
void kfree_skb_list(struct sk_buff *segs);
void skb_tx_error(struct sk_buff *skb);

26
net/core/dev.c
View File

@ -163,6 +163,7 @@ static int netif_rx_internal(struct sk_buff *skb);
static int call_netdevice_notifiers_info(unsigned long val,
struct net_device *dev,
struct netdev_notifier_info *info);
static struct napi_struct *napi_by_id(unsigned int napi_id);
/*
* The @dev_base_head list is protected by @dev_base_lock and the rtnl
@ -866,6 +867,31 @@ struct net_device *dev_get_by_index(struct net *net, int ifindex)
}
EXPORT_SYMBOL(dev_get_by_index);
/**
* dev_get_by_napi_id - find a device by napi_id
* @napi_id: ID of the NAPI struct
*
* Search for an interface by NAPI ID. Returns %NULL if the device
* is not found or a pointer to the device. The device has not had
* its reference counter increased so the caller must be careful
* about locking. The caller must hold RCU lock.
*/
struct net_device *dev_get_by_napi_id(unsigned int napi_id)
{
struct napi_struct *napi;
WARN_ON_ONCE(!rcu_read_lock_held());
if (napi_id < MIN_NAPI_ID)
return NULL;
napi = napi_by_id(napi_id);
return napi ? napi->dev : NULL;
}
EXPORT_SYMBOL(dev_get_by_napi_id);
/**
* netdev_get_name - get a netdevice name, knowing its ifindex.
* @net: network namespace