Hi Jules,
On Wed, Jan 25, 2023 at 04:39:59PM +0100, Jules Maselbas wrote:
> Using sendmsg_current to detect if a packet needs to be retransmitted is
> brittle as only packets containing data will ever be considered, packets
> only containing a header (without data) were never being retransmitted.
>
> The sendbuf_len is used to determine if a packets is being send or not,
> a non-zero length means that a packets is still being in the "try-send"
> state, the length is not set to zero when a valid SN is received.
>
> Retransmission issue can be easily reproduced with a physical UART (not
> cdc_acm over USB), by running the following command:
>
> while ratp-barebox-cli -b 115200 -t /dev/ttyACMx -p; do :; done
>
> Alternatively, it is possible to modify lib/ratp.c to force packets to
> be sent by the retransmission logic with the following change:
>
> @ int ratp_send_pkt(struct ratp_internal *ri, void *pkt, int length)
> ri->sendbuf_len = length;
> - ri->retransmission_timer_start = get_time_ns();
> + ri->retransmission_timer_start = get_time_ns() - ri->rto * MSECOND/2;
> ri->retransmission_count = 0;
> }
> - return ri->ratp->send(ri->ratp, pkt, length);
> + return 0;
>
> Signed-off-by: Jules Maselbas <jmaselbas@xxxxxxxxx>
> ---
> changes in v2: reset sendbuf_len to zero where appropriated (in each behavior)
>
> lib/ratp.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
Is this one still ok to be applied from your side?
This doesn't fix the issue you are mentioning in the other thread,
right?
Sascha
>
> diff --git a/lib/ratp.c b/lib/ratp.c
> index ce30223bac..b582e4e779 100644
> --- a/lib/ratp.c
> +++ b/lib/ratp.c
> @@ -738,7 +738,7 @@ static int ratp_behaviour_c2(struct ratp_internal *ri, void *pkt)
> control = RATP_CONTROL_RST | RATP_CONTROL_ACK |
> ratp_set_sn(ratp_an(hdr)) | ratp_set_next_an(ratp_sn(hdr));
> ratp_send_hdr(ri, control);
> -
> + ri->sendbuf_len = 0;
> ratp_state_change(ri, RATP_STATE_CLOSED);
> return 1;
> }
> @@ -784,7 +784,7 @@ static int ratp_behaviour_d1(struct ratp_internal *ri, void *pkt)
> ri->status = -ECONNREFUSED;
>
> pr_debug("Error: connection refused\n");
> -
> + ri->sendbuf_len = 0;
> ratp_state_change(ri, RATP_STATE_CLOSED);
>
> return 1;
> @@ -812,6 +812,8 @@ static int ratp_behaviour_d2(struct ratp_internal *ri, void *pkt)
> ri->status = -ECONNRESET;
>
> pr_debug("connection reset\n");
> + ri->sendbuf_len = 0;
> + ratp_state_change(ri, RATP_STATE_CLOSED);
>
> return 0;
> }
> @@ -879,7 +881,7 @@ static int ratp_behaviour_e(struct ratp_internal *ri, void *pkt)
> ratp_send_hdr(ri, control);
>
> pr_debug("connection reset\n");
> -
> + ri->sendbuf_len = 0;
> ratp_state_change(ri, RATP_STATE_CLOSED);
>
> return 1;
> @@ -924,8 +926,10 @@ static int ratp_behaviour_f1(struct ratp_internal *ri, void *pkt)
> if (!(hdr->control & RATP_CONTROL_ACK))
> return 1;
>
> - if (ratp_an_expected(ri, hdr))
> + if (ratp_an_expected(ri, hdr)) {
> + ri->sendbuf_len = 0; /* packet succesfully received */
> return 0;
> + }
>
> control = RATP_CONTROL_RST | ratp_set_sn(ratp_an(hdr));
> ratp_send_hdr(ri, control);
> @@ -971,6 +975,8 @@ static int ratp_behaviour_f2(struct ratp_internal *ri, void *pkt)
> if (ri->sendmsg_current)
> ratp_msg_done(ri, ri->sendmsg_current, 0);
> ri->sendmsg_current = NULL;
> + ri->sendbuf_len = 0; /* packet succesfully received */
> + pr_debug("Data succesfully sent 0\n");
> return 0;
> } else {
> pr_vdebug("%s: an not expected\n", __func__);
> @@ -1175,6 +1181,7 @@ static int ratp_behaviour_h3(struct ratp_internal *ri, void *pkt)
> ratp_send_hdr(ri, control);
> ri->status = -ECONNRESET;
> pr_debug("Error: Connection reset\n");
> + ri->sendbuf_len = 0;
> ratp_state_change(ri, RATP_STATE_CLOSED);
> return 1;
> }
> @@ -1217,8 +1224,10 @@ static int ratp_behaviour_h4(struct ratp_internal *ri, void *pkt)
>
> pr_debug("%s\n", __func__);
>
> - if (ratp_an_expected(ri, hdr))
> + if (ratp_an_expected(ri, hdr)) {
> + ri->sendbuf_len = 0; /* packet succesfully received */
> ratp_state_change(ri, RATP_STATE_CLOSED);
> + }
>
> return 1;
> }
> @@ -1244,6 +1253,7 @@ static int ratp_behaviour_h5(struct ratp_internal *ri, void *pkt)
> pr_debug("%s\n", __func__);
>
> if (ratp_an_expected(ri, hdr)) {
> + ri->sendbuf_len = 0; /* packet succesfully received */
> ratp_state_change(ri, RATP_STATE_TIME_WAIT);
> ratp_start_time_wait_timer(ri);
> }
> @@ -1580,9 +1590,8 @@ int ratp_poll(struct ratp *ratp)
> }
> }
>
> - if (ri->sendmsg_current && is_timeout(ri->retransmission_timer_start,
> + if (ri->sendbuf_len && is_timeout(ri->retransmission_timer_start,
> ri->rto * MSECOND)) {
> -
> ri->retransmission_count++;
> if (ri->retransmission_count == ri->max_retransmission) {
> ri->status = ret = -ETIMEDOUT;
> @@ -1601,7 +1610,7 @@ int ratp_poll(struct ratp *ratp)
> goto out;
> }
>
> - if (!ri->sendmsg_current && !list_empty(&ri->sendmsg))
> + if (ri->sendbuf_len == 0 && !list_empty(&ri->sendmsg))
> ratp_send_next_data(ri);
>
> ret = 0;
> --
> 2.17.1
>
>
>
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