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author | David Howells <dhowells@redhat.com> | 2017-11-24 10:18:42 +0000 |
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committer | David Howells <dhowells@redhat.com> | 2017-11-24 10:18:42 +0000 |
commit | 415f44e43282a16ec0808c7ccfd401762e587437 (patch) | |
tree | f6ccecc27740451b869f783156394569c3161a78 /net/rxrpc/output.c | |
parent | bd1fdf8cfdf3fdbccd2b21c33ec649ebd7429af7 (diff) | |
download | linux-stable-415f44e43282a16ec0808c7ccfd401762e587437.tar.gz linux-stable-415f44e43282a16ec0808c7ccfd401762e587437.tar.bz2 linux-stable-415f44e43282a16ec0808c7ccfd401762e587437.zip |
rxrpc: Add keepalive for a call
We need to transmit a packet every so often to act as a keepalive for the
peer (which has a timeout from the last time it received a packet) and also
to prevent any intervening firewalls from closing the route.
Do this by resetting a timer every time we transmit a packet. If the timer
ever expires, we transmit a PING ACK packet and thereby also elicit a PING
RESPONSE ACK from the other side - which prevents our last-rx timeout from
expiring.
The timer is set to 1/6 of the last-rx timeout so that we can detect the
other side going away if it misses 6 replies in a row.
This is particularly necessary for servers where the processing of the
service function may take a significant amount of time.
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc/output.c')
-rw-r--r-- | net/rxrpc/output.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index efe06edce189..42410e910aff 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -33,6 +33,24 @@ struct rxrpc_abort_buffer { }; /* + * Arrange for a keepalive ping a certain time after we last transmitted. This + * lets the far side know we're still interested in this call and helps keep + * the route through any intervening firewall open. + * + * Receiving a response to the ping will prevent the ->expect_rx_by timer from + * expiring. + */ +static void rxrpc_set_keepalive(struct rxrpc_call *call) +{ + unsigned long now = jiffies, keepalive_at = call->next_rx_timo / 6; + + keepalive_at += now; + WRITE_ONCE(call->keepalive_at, keepalive_at); + rxrpc_reduce_call_timer(call, keepalive_at, now, + rxrpc_timer_set_for_keepalive); +} + +/* * Fill out an ACK packet. */ static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn, @@ -205,6 +223,8 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping, call->ackr_seen = top; spin_unlock_bh(&call->lock); } + + rxrpc_set_keepalive(call); } out: @@ -388,6 +408,9 @@ done: } } } + + rxrpc_set_keepalive(call); + _leave(" = %d [%u]", ret, call->peer->maxdata); return ret; |