From f6d963b5d927e67389b40bd6618378b773ef5137 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: Thu, 1 Oct 2020 20:42:50 +0200
Subject: [PATCH] isotpsend: add support for blocking write flag

With the new flag 'CAN_ISOTP_WAIT_TX_DONE' the send()/write() syscall returns
when the PDU is completely passed to the CAN netdevice queue. Depending on
STmin and other settings for the tx-queue-len this does not necessarily mean
that the PDU has been completely sent on the CAN interface at that time.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 include/linux/can/isotp.h | 1 +
 isotpsend.c               | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/can/isotp.h b/include/linux/can/isotp.h
index f074329..09935b5 100644
--- a/include/linux/can/isotp.h
+++ b/include/linux/can/isotp.h
@@ -136,6 +136,7 @@ struct can_isotp_ll_options {
 #define CAN_ISOTP_FORCE_TXSTMIN	0x080	/* ignore stmin from received FC */
 #define CAN_ISOTP_FORCE_RXSTMIN	0x100	/* ignore CFs depending on rx stmin */
 #define CAN_ISOTP_RX_EXT_ADDR	0x200	/* different rx extended addressing */
+#define CAN_ISOTP_WAIT_TX_DONE	0x400	/* wait for tx completion */
 
 
 /* default values */
diff --git a/isotpsend.c b/isotpsend.c
index c32add3..3797e95 100644
--- a/isotpsend.c
+++ b/isotpsend.c
@@ -71,6 +71,7 @@ void print_usage(char *prg)
 	fprintf(stderr, "         -t <time ns>  (frame transmit time (N_As) in nanosecs)\n");
 	fprintf(stderr, "         -f <time ns>  (ignore FC and force local tx stmin value in nanosecs)\n");
 	fprintf(stderr, "         -D <len>      (send a fixed PDU with len bytes - no STDIN data)\n");
+	fprintf(stderr, "         -b            (block until the PDU transmission is completed)\n");
 	fprintf(stderr, "         -L <mtu>:<tx_dl>:<tx_flags>  (link layer options for CAN FD)\n");
 	fprintf(stderr, "\nCAN IDs and addresses are given and expected in hexadecimal values.\n");
 	fprintf(stderr, "The pdu data is expected on STDIN in space separated ASCII hex values.\n");
@@ -93,7 +94,7 @@ int main(int argc, char **argv)
 
     addr.can_addr.tp.tx_id = addr.can_addr.tp.rx_id = NO_CAN_ID;
 
-    while ((opt = getopt(argc, argv, "s:d:x:p:P:t:f:D:L:?")) != -1) {
+    while ((opt = getopt(argc, argv, "s:d:x:p:P:t:f:D:bL:?")) != -1) {
 	    switch (opt) {
 	    case 's':
 		    addr.can_addr.tp.tx_id = strtoul(optarg, (char **)NULL, 16);
@@ -176,6 +177,10 @@ int main(int argc, char **argv)
 		    }
 		    break;
 
+	    case 'b':
+		    opts.flags |= CAN_ISOTP_WAIT_TX_DONE;
+		    break;
+
 	    case 'L':
 		    if (sscanf(optarg, "%hhu:%hhu:%hhu",
 			       &llopts.mtu,