From a5af7e1fc69a46f29b977fd4b570e0ac414c2338 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 6 Oct 2016 08:11:49 +0100 Subject: rxrpc: Fix loss of PING RESPONSE ACK production due to PING ACKs Separate the output of PING ACKs from the output of other sorts of ACK so that if we receive a PING ACK and schedule transmission of a PING RESPONSE ACK, the response doesn't get cancelled by a PING ACK we happen to be scheduling transmission of at the same time. If a PING RESPONSE gets lost, the other side might just sit there waiting for it and refuse to proceed otherwise. Signed-off-by: David Howells --- net/rxrpc/call_event.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 44 insertions(+), 4 deletions(-) (limited to 'net/rxrpc/call_event.c') diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index e313099860d5..eeea9602cb89 100644 --- a/net/rxrpc/call_event.c +++ b/net/rxrpc/call_event.c @@ -54,6 +54,14 @@ void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why, t = call->ack_at; } + if (!ktime_after(call->ping_at, now)) { + call->ping_at = call->expire_at; + if (!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events)) + queue = true; + } else if (ktime_before(call->ping_at, t)) { + t = call->ping_at; + } + t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now))); t_j += jiffies; @@ -77,6 +85,27 @@ out: read_unlock_bh(&call->state_lock); } +/* + * Propose a PING ACK be sent. + */ +static void rxrpc_propose_ping(struct rxrpc_call *call, + bool immediate, bool background) +{ + if (immediate) { + if (background && + !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events)) + rxrpc_queue_call(call); + } else { + ktime_t now = ktime_get_real(); + ktime_t ping_at = ktime_add_ms(now, rxrpc_idle_ack_delay); + + if (ktime_before(ping_at, call->ping_at)) { + call->ping_at = ping_at; + rxrpc_set_timer(call, rxrpc_timer_set_for_ping, now); + } + } +} + /* * propose an ACK be sent */ @@ -90,6 +119,14 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, ktime_t now, ack_at; s8 prior = rxrpc_ack_priority[ack_reason]; + /* Pings are handled specially because we don't want to accidentally + * lose a ping response by subsuming it into a ping. + */ + if (ack_reason == RXRPC_ACK_PING) { + rxrpc_propose_ping(call, immediate, background); + goto trace; + } + /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial * numbers, but we don't alter the timeout. */ @@ -125,7 +162,6 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, expiry = rxrpc_soft_ack_delay; break; - case RXRPC_ACK_PING: case RXRPC_ACK_IDLE: if (rxrpc_idle_ack_delay < expiry) expiry = rxrpc_idle_ack_delay; @@ -253,7 +289,7 @@ static void rxrpc_resend(struct rxrpc_call *call, ktime_t now) goto out; rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false, rxrpc_propose_ack_ping_for_lost_ack); - rxrpc_send_ack_packet(call); + rxrpc_send_ack_packet(call, true); goto out; } @@ -345,13 +381,17 @@ recheck_state: } if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events)) { - call->ack_at = call->expire_at; if (call->ackr_reason) { - rxrpc_send_ack_packet(call); + rxrpc_send_ack_packet(call, false); goto recheck_state; } } + if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) { + rxrpc_send_ack_packet(call, true); + goto recheck_state; + } + if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) { rxrpc_resend(call, now); goto recheck_state; -- cgit v1.2.3-70-g09d2