[PATCH 5.11 148/254] can: isotp: TX-path: ensure that CAN frame flags are initialized

From: Greg Kroah-Hartman
Date: Mon Mar 29 2021 - 05:00:36 EST


From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>

[ Upstream commit d4eb538e1f48b3cf7bb6cb9eb39fe3e9e8a701f7 ]

The previous patch ensures that the TX flags (struct
can_isotp_ll_options::tx_flags) are 0 for classic CAN frames or a user
configured value for CAN-FD frames.

This patch sets the CAN frames flags unconditionally to the ISO-TP TX
flags, so that they are initialized to a proper value. Otherwise when
running "candump -x" on a classical CAN ISO-TP stream shows wrongly
set "B" and "E" flags.

| $ candump any,0:0,#FFFFFFFF -extA
| [...]
| can0 TX B E 713 [8] 2B 0A 0B 0C 0D 0E 0F 00
| can0 TX B E 713 [8] 2C 01 02 03 04 05 06 07
| can0 TX B E 713 [8] 2D 08 09 0A 0B 0C 0D 0E
| can0 TX B E 713 [8] 2E 0F 00 01 02 03 04 05

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Link: https://lore.kernel.org/r/20210218215434.1708249-2-mkl@xxxxxxxxxxxxxx
Cc: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/can/isotp.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index e32d446c121e..430976485d95 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -215,8 +215,7 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus)
if (ae)
ncf->data[0] = so->opt.ext_address;

- if (so->ll.mtu == CANFD_MTU)
- ncf->flags = so->ll.tx_flags;
+ ncf->flags = so->ll.tx_flags;

can_send_ret = can_send(nskb, 1);
if (can_send_ret)
@@ -790,8 +789,7 @@ isotp_tx_burst:
so->tx.sn %= 16;
so->tx.bs++;

- if (so->ll.mtu == CANFD_MTU)
- cf->flags = so->ll.tx_flags;
+ cf->flags = so->ll.tx_flags;

skb->dev = dev;
can_skb_set_owner(skb, sk);
@@ -939,8 +937,7 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
}

/* send the first or only CAN frame */
- if (so->ll.mtu == CANFD_MTU)
- cf->flags = so->ll.tx_flags;
+ cf->flags = so->ll.tx_flags;

skb->dev = dev;
skb->sk = sk;
--
2.30.1