Subject: Re: [PATCH net-next v7 2/6] can: add CAN skb extension infrastructure

From: kernel test robot <[email-masked]>
Date: Sun, 1 Feb 2026 05:02:25 +0800

Hi Oliver,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 239f09e258b906deced5c2a7c1ac8aed301b558b]

url:    https://github.com/intel-lab-lkp/linux/commits/Oliver-Hartkopp-via-B4-Relay/can-use-skb-hash-instead-of-private-variable-in-headroom/20260131-212921
base:   239f09e258b906deced5c2a7c1ac8aed301b558b
patch link:    https://lore.kernel.org/r/20260131-can_skb_ext-v7-2-dd0f8f84a83d%40hartkopp.net
patch subject: [PATCH net-next v7 2/6] can: add CAN skb extension infrastructure
config: s390-randconfig-r072-20260201 (https://download.01.org/0day-ci/archive/20260201/[email-masked]/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
smatch version: v0.5.0-8994-gd50c5a4c

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email-masked]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/

smatch warnings:
net/can/j1939/transport.c:1073 j1939_simple_txnext() warn: inconsistent indenting

vim +1073 net/can/j1939/transport.c

9d71dd0c700999 The j1939 authors 2018-10-08  1045  
9d71dd0c700999 The j1939 authors 2018-10-08  1046  static int j1939_simple_txnext(struct j1939_session *session)
9d71dd0c700999 The j1939 authors 2018-10-08  1047  {
9d71dd0c700999 The j1939 authors 2018-10-08  1048  	struct j1939_priv *priv = session->priv;
2030043e616cab Oleksij Rempel    2021-05-21  1049  	struct sk_buff *se_skb = j1939_session_skb_get(session);
9d71dd0c700999 The j1939 authors 2018-10-08  1050  	struct sk_buff *skb;
9d71dd0c700999 The j1939 authors 2018-10-08  1051  	int ret;
9d71dd0c700999 The j1939 authors 2018-10-08  1052  
9d71dd0c700999 The j1939 authors 2018-10-08  1053  	if (!se_skb)
9d71dd0c700999 The j1939 authors 2018-10-08  1054  		return 0;
9d71dd0c700999 The j1939 authors 2018-10-08  1055  
9d71dd0c700999 The j1939 authors 2018-10-08  1056  	skb = skb_clone(se_skb, GFP_ATOMIC);
2030043e616cab Oleksij Rempel    2021-05-21  1057  	if (!skb) {
2030043e616cab Oleksij Rempel    2021-05-21  1058  		ret = -ENOMEM;
2030043e616cab Oleksij Rempel    2021-05-21  1059  		goto out_free;
2030043e616cab Oleksij Rempel    2021-05-21  1060  	}
9d71dd0c700999 The j1939 authors 2018-10-08  1061  
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1062  	/* the cloned skb points to the skb extension of the original se_skb
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1063  	 * with an increased refcount. skb_ext_add() creates a copy to
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1064  	 * separate the skb extension data which is needed to modify the
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1065  	 * can_framelen in can_put_echo_skb().
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1066  	 */
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1067  	if (!skb_ext_add(skb, SKB_EXT_CAN)) {
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1068  		kfree_skb(skb);
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1069  		ret = -ENOMEM;
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1070  		goto out_free;
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1071  	}
f170b16e1461f2 Oliver Hartkopp   2026-01-31  1072  
9d71dd0c700999 The j1939 authors 2018-10-08 @1073         can_skb_set_owner(skb, se_skb->sk);
9d71dd0c700999 The j1939 authors 2018-10-08  1074  
9d71dd0c700999 The j1939 authors 2018-10-08  1075  	j1939_tp_set_rxtimeout(session, J1939_SIMPLE_ECHO_TIMEOUT_MS);
9d71dd0c700999 The j1939 authors 2018-10-08  1076  
9d71dd0c700999 The j1939 authors 2018-10-08  1077  	ret = j1939_send_one(priv, skb);
9d71dd0c700999 The j1939 authors 2018-10-08  1078  	if (ret)
2030043e616cab Oleksij Rempel    2021-05-21  1079  		goto out_free;
9d71dd0c700999 The j1939 authors 2018-10-08  1080  
cd85d3aed5cf44 Oleksij Rempel    2021-07-07  1081  	j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_SCHED);
9d71dd0c700999 The j1939 authors 2018-10-08  1082  	j1939_sk_queue_activate_next(session);
9d71dd0c700999 The j1939 authors 2018-10-08  1083  
2030043e616cab Oleksij Rempel    2021-05-21  1084   out_free:
2030043e616cab Oleksij Rempel    2021-05-21  1085  	if (ret)
2030043e616cab Oleksij Rempel    2021-05-21  1086  		kfree_skb(se_skb);
2030043e616cab Oleksij Rempel    2021-05-21  1087  	else
2030043e616cab Oleksij Rempel    2021-05-21  1088  		consume_skb(se_skb);
2030043e616cab Oleksij Rempel    2021-05-21  1089  
2030043e616cab Oleksij Rempel    2021-05-21  1090  	return ret;
9d71dd0c700999 The j1939 authors 2018-10-08  1091  }
9d71dd0c700999 The j1939 authors 2018-10-08  1092  

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