summaryrefslogtreecommitdiffstats
path: root/net/rxrpc/input.c
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2017-11-24 10:18:42 +0000
committerDavid Howells <dhowells@redhat.com>2017-11-24 10:18:42 +0000
commitbd1fdf8cfdf3fdbccd2b21c33ec649ebd7429af7 (patch)
treea4bd170409584ba9950b3193cd11213fb2552694 /net/rxrpc/input.c
parentbeb8e5e4f38cc3e4c2839cfc143e0312bf53d0e0 (diff)
downloadlinux-bd1fdf8cfdf3fdbccd2b21c33ec649ebd7429af7.tar.bz2
rxrpc: Add a timeout for detecting lost ACKs/lost DATA
Add an extra timeout that is set/updated when we send a DATA packet that has the request-ack flag set. This allows us to detect if we don't get an ACK in response to the latest flagged packet. The ACK packet is adjudged to have been lost if it doesn't turn up within 2*RTT of the transmission. If the timeout occurs, we schedule the sending of a PING ACK to find out the state of the other side. If a new DATA packet is ready to go sooner, we cancel the sending of the ping and set the request-ack flag on that instead. If we get back a PING-RESPONSE ACK that indicates a lower tx_top than what we had at the time of the ping transmission, we adjudge all the DATA packets sent between the response tx_top and the ping-time tx_top to have been lost and retransmit immediately. Rather than sending a PING ACK, we could just pick a DATA packet and speculatively retransmit that with request-ack set. It should result in either a REQUESTED ACK or a DUPLICATE ACK which we can then use in lieu the a PING-RESPONSE ACK mentioned above. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc/input.c')
-rw-r--r--net/rxrpc/input.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index c89647eae86d..23a5e61d8f79 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -631,6 +631,43 @@ found:
}
/*
+ * Process the response to a ping that we sent to find out if we lost an ACK.
+ *
+ * If we got back a ping response that indicates a lower tx_top than what we
+ * had at the time of the ping transmission, we adjudge all the DATA packets
+ * sent between the response tx_top and the ping-time tx_top to have been lost.
+ */
+static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
+{
+ rxrpc_seq_t top, bottom, seq;
+ bool resend = false;
+
+ spin_lock_bh(&call->lock);
+
+ bottom = call->tx_hard_ack + 1;
+ top = call->acks_lost_top;
+ if (before(bottom, top)) {
+ for (seq = bottom; before_eq(seq, top); seq++) {
+ int ix = seq & RXRPC_RXTX_BUFF_MASK;
+ u8 annotation = call->rxtx_annotations[ix];
+ u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
+
+ if (anno_type != RXRPC_TX_ANNO_UNACK)
+ continue;
+ annotation &= ~RXRPC_TX_ANNO_MASK;
+ annotation |= RXRPC_TX_ANNO_RETRANS;
+ call->rxtx_annotations[ix] = annotation;
+ resend = true;
+ }
+ }
+
+ spin_unlock_bh(&call->lock);
+
+ if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
+ rxrpc_queue_call(call);
+}
+
+/*
* Process a ping response.
*/
static void rxrpc_input_ping_response(struct rxrpc_call *call,
@@ -645,6 +682,9 @@ static void rxrpc_input_ping_response(struct rxrpc_call *call,
smp_rmb();
ping_serial = call->ping_serial;
+ if (orig_serial == call->acks_lost_ping)
+ rxrpc_input_check_for_lost_ack(call);
+
if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||
before(orig_serial, ping_serial))
return;