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net: tcp: Avoid new packets from causing killing the pending send_timer

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When there was no room to transmit the a next packet to be transmitted,
the -ENOBUFS could cause the retransmission to fail.

Secondly the conn->unacked_len can be set to 0 in the retransmission
process, causing the subscribtion to the transmit timer to fail. Use the
variable send_data_total instead.

Make sure that is the send_data buffer becomes empty the send_timer is
cancelled, but make sure any pending data still keeps on being transmitted.

Signed-off-by: Sjors Hettinga <s.a.hettinga@gmail.com>
This commit is contained in:
Sjors Hettinga 2022-05-23 10:16:11 +02:00 • committed by Carles Cufí
commit 0a9b2ed391
1 changed files with 13 additions and 9 deletions
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22
subsys/net/ip/tcp.c
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@ -1107,7 +1107,7 @@ static int tcp_send_queued_data(struct tcp *conn)
(void)k_sem_take(&conn->tx_sem, K_NO_WAIT);
}
if (conn->unacked_len) {
if (conn->send_data_total) {
subscribe = true;
}
@ -1115,14 +1115,6 @@ static int tcp_send_queued_data(struct tcp *conn)
subscribe = false;
}
/* If we have out-of-bufs case, then do not start retransmit timer
* yet. The socket layer will catch this and resend data if needed.
*/
if (ret == -ENOBUFS) {
NET_DBG("No bufs, cancelling retransmit timer");
k_work_cancel_delayable(&conn->send_data_timer);
}
if (subscribe) {
conn->send_data_retries = 0;
k_work_reschedule_for_queue(&tcp_work_q, &conn->send_data_timer,
@ -2370,6 +2362,18 @@ int net_tcp_queue_data(struct net_context *context, struct net_pkt *pkt)
pkt->buffer = conn->send_data->buffer;
conn->send_data->buffer = NULL;
}
/* If we have out-of-bufs case, and the send_data buffer has
* become empty, till the retransmit timer, as there is no
* data to retransmit.
* The socket layer will catch this and resend data if needed.
* Only perform this when it is just the newly added packet,
* otherwise it can disrupt any pending transmission
*/
if (conn->send_data_total == 0) {
NET_DBG("No bufs, cancelling retransmit timer");
k_work_cancel_delayable(&conn->send_data_timer);
}
} else {
/* We should not free the pkt if there was an error. It will be
* freed in net_context.c:context_sendto()