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7b14e15ae6
Currently, a MCTP (local-eid,remote-eid,tag) tuple is allocated to a socket on send, and only expires when the socket is closed. This change introduces a tag timeout, freeing the tuple after a fixed expiry - currently six seconds. This is greater than (but close to) the max response timeout in upper-layer bindings. Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> Signed-off-by: David S. Miller <davem@davemloft.net>
259 lines
6.9 KiB
C
259 lines
6.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Management Component Transport Protocol (MCTP)
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*
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* Copyright (c) 2021 Code Construct
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* Copyright (c) 2021 Google
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*/
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#ifndef __NET_MCTP_H
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#define __NET_MCTP_H
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#include <linux/bits.h>
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#include <linux/mctp.h>
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#include <net/net_namespace.h>
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#include <net/sock.h>
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/* MCTP packet definitions */
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struct mctp_hdr {
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u8 ver;
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u8 dest;
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u8 src;
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u8 flags_seq_tag;
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};
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#define MCTP_VER_MIN 1
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#define MCTP_VER_MAX 1
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/* Definitions for flags_seq_tag field */
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#define MCTP_HDR_FLAG_SOM BIT(7)
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#define MCTP_HDR_FLAG_EOM BIT(6)
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#define MCTP_HDR_FLAG_TO BIT(3)
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#define MCTP_HDR_FLAGS GENMASK(5, 3)
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#define MCTP_HDR_SEQ_SHIFT 4
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#define MCTP_HDR_SEQ_MASK GENMASK(1, 0)
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#define MCTP_HDR_TAG_SHIFT 0
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#define MCTP_HDR_TAG_MASK GENMASK(2, 0)
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#define MCTP_HEADER_MAXLEN 4
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#define MCTP_INITIAL_DEFAULT_NET 1
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static inline bool mctp_address_ok(mctp_eid_t eid)
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{
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return eid >= 8 && eid < 255;
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}
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static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb)
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{
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return (struct mctp_hdr *)skb_network_header(skb);
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}
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/* socket implementation */
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struct mctp_sock {
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struct sock sk;
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/* bind() params */
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int bind_net;
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mctp_eid_t bind_addr;
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__u8 bind_type;
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/* list of mctp_sk_key, for incoming tag lookup. updates protected
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* by sk->net->keys_lock
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*/
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struct hlist_head keys;
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/* mechanism for expiring allocated keys; will release an allocated
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* tag, and any netdev state for a request/response pairing
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*/
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struct timer_list key_expiry;
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};
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/* Key for matching incoming packets to sockets or reassembly contexts.
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* Packets are matched on (src,dest,tag).
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*
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* Lifetime / locking requirements:
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*
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* - individual key data (ie, the struct itself) is protected by key->lock;
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* changes must be made with that lock held.
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*
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* - the lookup fields: peer_addr, local_addr and tag are set before the
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* key is added to lookup lists, and never updated.
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*
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* - A ref to the key must be held (throuh key->refs) if a pointer to the
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* key is to be accessed after key->lock is released.
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*
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* - a mctp_sk_key contains a reference to a struct sock; this is valid
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* for the life of the key. On sock destruction (through unhash), the key is
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* removed from lists (see below), and marked invalid.
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*
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* - these mctp_sk_keys appear on two lists:
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* 1) the struct mctp_sock->keys list
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* 2) the struct netns_mctp->keys list
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*
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* presences on these lists requires a (single) refcount to be held; both
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* lists are updated as a single operation.
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*
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* Updates and lookups in either list are performed under the
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* netns_mctp->keys lock. Lookup functions will need to lock the key and
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* take a reference before unlocking the keys_lock. Consequently, the list's
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* keys_lock *cannot* be acquired with the individual key->lock held.
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*
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* - a key may have a sk_buff attached as part of an in-progress message
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* reassembly (->reasm_head). The reasm data is protected by the individual
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* key->lock.
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*
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* - there are two destruction paths for a mctp_sk_key:
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*
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* - through socket unhash (see mctp_sk_unhash). This performs the list
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* removal under keys_lock.
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*
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* - where a key is established to receive a reply message: after receiving
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* the (complete) reply, or during reassembly errors. Here, we clean up
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* the reassembly context (marking reasm_dead, to prevent another from
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* starting), and remove the socket from the netns & socket lists.
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*
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* - through an expiry timeout, on a per-socket timer
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*/
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struct mctp_sk_key {
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mctp_eid_t peer_addr;
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mctp_eid_t local_addr;
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__u8 tag; /* incoming tag match; invert TO for local */
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/* we hold a ref to sk when set */
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struct sock *sk;
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/* routing lookup list */
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struct hlist_node hlist;
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/* per-socket list */
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struct hlist_node sklist;
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/* lock protects against concurrent updates to the reassembly and
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* expiry data below.
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*/
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spinlock_t lock;
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/* Keys are referenced during the output path, which may sleep */
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refcount_t refs;
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/* incoming fragment reassembly context */
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struct sk_buff *reasm_head;
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struct sk_buff **reasm_tailp;
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bool reasm_dead;
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u8 last_seq;
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/* key validity */
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bool valid;
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/* expiry timeout; valid (above) cleared on expiry */
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unsigned long expiry;
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};
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struct mctp_skb_cb {
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unsigned int magic;
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unsigned int net;
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mctp_eid_t src;
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};
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/* skb control-block accessors with a little extra debugging for initial
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* development.
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*
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* TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb
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* with mctp_cb().
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*
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* __mctp_cb() is only for the initial ingress code; we should see ->magic set
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* at all times after this.
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*/
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static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb)
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{
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struct mctp_skb_cb *cb = (void *)skb->cb;
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cb->magic = 0x4d435450;
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return cb;
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}
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static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb)
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{
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struct mctp_skb_cb *cb = (void *)skb->cb;
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WARN_ON(cb->magic != 0x4d435450);
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return (void *)(skb->cb);
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}
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/* Route definition.
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*
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* These are held in the pernet->mctp.routes list, with RCU protection for
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* removed routes. We hold a reference to the netdev; routes need to be
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* dropped on NETDEV_UNREGISTER events.
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*
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* Updates to the route table are performed under rtnl; all reads under RCU,
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* so routes cannot be referenced over a RCU grace period. Specifically: A
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* caller cannot block between mctp_route_lookup and passing the route to
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* mctp_do_route.
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*/
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struct mctp_route {
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mctp_eid_t min, max;
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struct mctp_dev *dev;
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unsigned int mtu;
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unsigned char type;
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int (*output)(struct mctp_route *route,
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struct sk_buff *skb);
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struct list_head list;
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refcount_t refs;
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struct rcu_head rcu;
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};
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/* route interfaces */
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struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
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mctp_eid_t daddr);
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int mctp_do_route(struct mctp_route *rt, struct sk_buff *skb);
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int mctp_local_output(struct sock *sk, struct mctp_route *rt,
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struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
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void mctp_key_unref(struct mctp_sk_key *key);
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/* routing <--> device interface */
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unsigned int mctp_default_net(struct net *net);
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int mctp_default_net_set(struct net *net, unsigned int index);
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int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr);
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int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr);
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void mctp_route_remove_dev(struct mctp_dev *mdev);
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/* neighbour definitions */
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enum mctp_neigh_source {
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MCTP_NEIGH_STATIC,
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MCTP_NEIGH_DISCOVER,
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};
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struct mctp_neigh {
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struct mctp_dev *dev;
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mctp_eid_t eid;
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enum mctp_neigh_source source;
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unsigned char ha[MAX_ADDR_LEN];
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struct list_head list;
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struct rcu_head rcu;
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};
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int mctp_neigh_init(void);
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void mctp_neigh_exit(void);
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// ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN
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int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid,
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void *ret_hwaddr);
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void mctp_neigh_remove_dev(struct mctp_dev *mdev);
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int mctp_routes_init(void);
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void mctp_routes_exit(void);
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void mctp_device_init(void);
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void mctp_device_exit(void);
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#endif /* __NET_MCTP_H */
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