[RFC PATCH] ratp: Fix retransmission for header-only packets

[RFC PATCH] ratp: Fix retransmission for header-only packets

[Jules Maselbas]

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@kalray.eu>
---
 lib/ratp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/ratp.c b/lib/ratp.c
index ce30223bac..afa76ac894 100644
--- a/lib/ratp.c
+++ b/lib/ratp.c
@@ -1391,6 +1391,9 @@ static int ratp_state_machine(struct ratp_internal *ri, void *pkt)
 	ratp_print_header(ri, hdr, "                      recv");
 	pr_debug(" state %s\n", ratp_state_str[ri->state]);
 
+	if ((hdr->control & RATP_CONTROL_ACK) && (ratp_an_expected(ri, hdr)))
+		ri->sendbuf_len = 0;
+
 	switch (ri->state) {
 	case RATP_STATE_LISTEN:
 		ratp_behaviour_a(ri, pkt);
@@ -1580,9 +1583,8 @@ 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 +1603,7 @@ 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

[PATCH v2] ratp: Fix retransmission for header-only packets

[Jules Maselbas]

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@kalray.eu>
---
changes in v2: reset sendbuf_len to zero where appropriated (in each behavior)

lib/ratp.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

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

Re: [PATCH v2] ratp: Fix retransmission for header-only packets

[Jules Maselbas]

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@kalray.eu>
> ---
> changes in v2: reset sendbuf_len to zero where appropriated (in each behavior)
> 
> lib/ratp.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
> 
> 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");
This pr_debug line was not intended to be included.

>  		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
> 

Re: [PATCH v2] ratp: Fix retransmission for header-only packets

[Sascha Hauer]

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@kalray.eu>
> ---
> 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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Re: [PATCH v2] ratp: Fix retransmission for header-only packets

[Jules Maselbas]

Hi Sascha,

On Fri, Feb 03, 2023 at 09:16:08AM +0100, Sascha Hauer wrote:
> 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@kalray.eu>
> > ---
> > 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?
No, I will send a new series with some additional patches.

> This doesn't fix the issue you are mentioning in the other thread,
> right?
It does fix an issue but it is not sufficient, but the RATP protcol needs
to fix as well

> 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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