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mctp: Implement a timeout for tags

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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>
This commit is contained in:
Jeremy Kerr 2021-09-29 15:26:09 +08:00 committed by David S. Miller
parent 43f55f23f7
commit 7b14e15ae6
3 changed files with 62 additions and 0 deletions
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10
include/net/mctp.h
View File

@ -62,6 +62,11 @@ struct mctp_sock {
* by sk->net->keys_lock
*/
struct hlist_head keys;
/* mechanism for expiring allocated keys; will release an allocated
* tag, and any netdev state for a request/response pairing
*/
struct timer_list key_expiry;
};
/* Key for matching incoming packets to sockets or reassembly contexts.
@ -107,6 +112,8 @@ struct mctp_sock {
* the (complete) reply, or during reassembly errors. Here, we clean up
* the reassembly context (marking reasm_dead, to prevent another from
* starting), and remove the socket from the netns & socket lists.
*
* - through an expiry timeout, on a per-socket timer
*/
struct mctp_sk_key {
mctp_eid_t peer_addr;
@ -138,6 +145,9 @@ struct mctp_sk_key {
/* key validity */
bool valid;
/* expiry timeout; valid (above) cleared on expiry */
unsigned long expiry;
};
struct mctp_skb_cb {

44
net/mctp/af_mctp.c
View File

@ -223,16 +223,60 @@ static const struct proto_ops mctp_dgram_ops = {
.sendpage = sock_no_sendpage,
};
static void mctp_sk_expire_keys(struct timer_list *timer)
{
struct mctp_sock *msk = container_of(timer, struct mctp_sock,
key_expiry);
struct net *net = sock_net(&msk->sk);
unsigned long next_expiry, flags;
struct mctp_sk_key *key;
struct hlist_node *tmp;
bool next_expiry_valid = false;
spin_lock_irqsave(&net->mctp.keys_lock, flags);
hlist_for_each_entry_safe(key, tmp, &msk->keys, sklist) {
spin_lock(&key->lock);
if (!time_after_eq(key->expiry, jiffies)) {
key->valid = false;
hlist_del_rcu(&key->hlist);
hlist_del_rcu(&key->sklist);
spin_unlock(&key->lock);
mctp_key_unref(key);
continue;
}
if (next_expiry_valid) {
if (time_before(key->expiry, next_expiry))
next_expiry = key->expiry;
} else {
next_expiry = key->expiry;
next_expiry_valid = true;
}
spin_unlock(&key->lock);
}
spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
if (next_expiry_valid)
mod_timer(timer, next_expiry);
}
static int mctp_sk_init(struct sock *sk)
{
struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
INIT_HLIST_HEAD(&msk->keys);
timer_setup(&msk->key_expiry, mctp_sk_expire_keys, 0);
return 0;
}
static void mctp_sk_close(struct sock *sk, long timeout)
{
struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
del_timer_sync(&msk->key_expiry);
sk_common_release(sk);
}

8
net/mctp/route.c
View File

@ -24,6 +24,8 @@
#include <net/sock.h>
static const unsigned int mctp_message_maxlen = 64 * 1024;
static const unsigned long mctp_key_lifetime = 6 * CONFIG_HZ;
/* route output callbacks */
static int mctp_route_discard(struct mctp_route *route, struct sk_buff *skb)
@ -175,6 +177,9 @@ static int mctp_key_add(struct mctp_sk_key *key, struct mctp_sock *msk)
if (!rc) {
refcount_inc(&key->refs);
key->expiry = jiffies + mctp_key_lifetime;
timer_reduce(&msk->key_expiry, key->expiry);
hlist_add_head(&key->hlist, &net->mctp.keys);
hlist_add_head(&key->sklist, &msk->keys);
}
@ -497,6 +502,9 @@ static void mctp_reserve_tag(struct net *net, struct mctp_sk_key *key,
lockdep_assert_held(&mns->keys_lock);
key->expiry = jiffies + mctp_key_lifetime;
timer_reduce(&msk->key_expiry, key->expiry);
/* we hold the net->key_lock here, allowing updates to both
* then net and sk
*/