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authorDavid Howells <dhowells@redhat.com>2016-10-06 10:11:49 +0300
committerDavid Howells <dhowells@redhat.com>2016-10-06 10:11:49 +0300
commita5af7e1fc69a46f29b977fd4b570e0ac414c2338 (patch)
treed3ecc4df97f90a40d3f3aa6827bfe4201eba71e7 /net/rxrpc/call_event.c
parent26cb02aa6d3efeb543805ed9ad599dae24f7c6d4 (diff)
downloadlinux-a5af7e1fc69a46f29b977fd4b570e0ac414c2338.tar.xz
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 <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc/call_event.c')
-rw-r--r--net/rxrpc/call_event.c48
1 files changed, 44 insertions, 4 deletions
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;
@@ -78,6 +86,27 @@ out:
}
/*
+ * 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
*/
static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
@@ -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;