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authorDavid Howells <dhowells@redhat.com>2017-11-24 10:18:42 +0000
committerDavid Howells <dhowells@redhat.com>2017-11-24 10:18:42 +0000
commit415f44e43282a16ec0808c7ccfd401762e587437 (patch)
treef6ccecc27740451b869f783156394569c3161a78 /net
parentbd1fdf8cfdf3fdbccd2b21c33ec649ebd7429af7 (diff)
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')
-rw-r--r--net/rxrpc/ar-internal.h1
-rw-r--r--net/rxrpc/call_event.c10
-rw-r--r--net/rxrpc/output.c23
3 files changed, 34 insertions, 0 deletions
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 7e7b817c69f0..cdcbc798f921 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -519,6 +519,7 @@ struct rxrpc_call {
unsigned long ack_lost_at; /* When ACK is figured as lost */
unsigned long resend_at; /* When next resend needs to happen */
unsigned long ping_at; /* When next to send a ping */
+ unsigned long keepalive_at; /* When next to send a keepalive ping */
unsigned long expect_rx_by; /* When we expect to get a packet by */
unsigned long expect_req_by; /* When we expect to get a request DATA packet by */
unsigned long expect_term_by; /* When we expect call termination by */
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index c65666b2f39e..bda952ffe6a6 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -366,6 +366,15 @@ recheck_state:
set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
}
+ t = READ_ONCE(call->keepalive_at);
+ if (time_after_eq(now, t)) {
+ trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
+ cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
+ rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, true,
+ rxrpc_propose_ack_ping_for_keepalive);
+ set_bit(RXRPC_CALL_EV_PING, &call->events);
+ }
+
t = READ_ONCE(call->ping_at);
if (time_after_eq(now, t)) {
trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
@@ -423,6 +432,7 @@ recheck_state:
set(call->ack_at);
set(call->ack_lost_at);
set(call->resend_at);
+ set(call->keepalive_at);
set(call->ping_at);
now = jiffies;
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;