Hi, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on next-20220214] [cannot apply to net-next/master rostedt-trace/for-next net/master linus/master v5.17-rc4 v5.17-rc3 v5.17-rc2 v5.17-rc4] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/menglong8-dong-gmail-com/net-add... base: 259cbfc98c55ba3b6ef6e61fb7cfc3751dfded1e config: i386-randconfig-a004-20220214 (https://download.01.org/0day-ci/archive/20220215/202202152352.9jAkQxUc-lk...) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 37f422f4ac31c8b8041c6b62065263314282dab6) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/8619663f7f150a5f5d782d8f6083988f5... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review menglong8-dong-gmail-com/net-add-skb-drop-reasons-for-TCP-IP-dev-and-neigh/20220215-193437 git checkout 8619663f7f150a5f5d782d8f6083988f56505777 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash net/ipv6/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): if (tcp_rcv_state_process(sk, skb)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/ipv6/tcp_ipv6.c:1567:24: note: uninitialized use occurs here kfree_skb_reason(skb, reason); ^~~~~~ net/ipv6/tcp_ipv6.c:1556:2: note: remove the 'if' if its condition is always false if (tcp_rcv_state_process(sk, skb)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/ipv6/tcp_ipv6.c:1547:8: warning: variable 'reason' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (tcp_child_process(sk, nsk, skb)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/ipv6/tcp_ipv6.c:1567:24: note: uninitialized use occurs here kfree_skb_reason(skb, reason); ^~~~~~ net/ipv6/tcp_ipv6.c:1547:4: note: remove the 'if' if its condition is always false if (tcp_child_process(sk, nsk, skb)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/ipv6/tcp_ipv6.c:1543:7: warning: variable 'reason' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (!nsk) ^~~~ net/ipv6/tcp_ipv6.c:1567:24: note: uninitialized use occurs here kfree_skb_reason(skb, reason); ^~~~~~ net/ipv6/tcp_ipv6.c:1543:3: note: remove the 'if' if its condition is always false if (!nsk) ^~~~~~~~~ net/ipv6/tcp_ipv6.c:1479:2: note: variable 'reason' is declared here enum skb_drop_reason reason; ^ 3 warnings generated. vim +1556 net/ipv6/tcp_ipv6.c ^1da177e4c3f41 Linus Torvalds 2005-04-16 1463 bbd807dfbf2050 Brian Vazquez 2021-02-01 1464 INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *, bbd807dfbf2050 Brian Vazquez 2021-02-01 1465 u32)); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1466 /* The socket must have it's spinlock held when we get e994b2f0fb9229 Eric Dumazet 2015-10-02 1467 * here, unless it is a TCP_LISTEN socket. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1468 * ^1da177e4c3f41 Linus Torvalds 2005-04-16 1469 * We have a potential double-lock case here, so even when ^1da177e4c3f41 Linus Torvalds 2005-04-16 1470 * doing backlog processing we use the BH locking scheme. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1471 * This is because we cannot sleep with the original spinlock ^1da177e4c3f41 Linus Torvalds 2005-04-16 1472 * held. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1473 */ d2489c7b6d7d5e Eric Dumazet 2021-11-15 1474 INDIRECT_CALLABLE_SCOPE d2489c7b6d7d5e Eric Dumazet 2021-11-15 1475 int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1476 { 93a77c11ae79e8 Eric Dumazet 2019-03-19 1477 struct ipv6_pinfo *np = tcp_inet6_sk(sk); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1478 struct sk_buff *opt_skb = NULL; 8619663f7f150a Menglong Dong 2022-02-15 1479 enum skb_drop_reason reason; 93a77c11ae79e8 Eric Dumazet 2019-03-19 1480 struct tcp_sock *tp; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1481 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1482 /* Imagine: socket is IPv6. IPv4 packet arrives, ^1da177e4c3f41 Linus Torvalds 2005-04-16 1483 goes to IPv4 receive handler and backlogged. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1484 From backlog it always goes here. Kerboom... ^1da177e4c3f41 Linus Torvalds 2005-04-16 1485 Fortunately, tcp_rcv_established and rcv_established ^1da177e4c3f41 Linus Torvalds 2005-04-16 1486 handle them correctly, but it is not case with ^1da177e4c3f41 Linus Torvalds 2005-04-16 1487 tcp_v6_hnd_req and tcp_v6_send_reset(). --ANK ^1da177e4c3f41 Linus Torvalds 2005-04-16 1488 */ ^1da177e4c3f41 Linus Torvalds 2005-04-16 1489 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1490 if (skb->protocol == htons(ETH_P_IP)) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1491 return tcp_v4_do_rcv(sk, skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1492 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1493 /* ^1da177e4c3f41 Linus Torvalds 2005-04-16 1494 * socket locking is here for SMP purposes as backlog rcv ^1da177e4c3f41 Linus Torvalds 2005-04-16 1495 * is currently called with bh processing disabled. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1496 */ ^1da177e4c3f41 Linus Torvalds 2005-04-16 1497 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1498 /* Do Stevens' IPV6_PKTOPTIONS. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1499 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1500 Yes, guys, it is the only place in our code, where we ^1da177e4c3f41 Linus Torvalds 2005-04-16 1501 may make it not affecting IPv4. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1502 The rest of code is protocol independent, ^1da177e4c3f41 Linus Torvalds 2005-04-16 1503 and I do not like idea to uglify IPv4. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1504 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1505 Actually, all the idea behind IPV6_PKTOPTIONS ^1da177e4c3f41 Linus Torvalds 2005-04-16 1506 looks not very well thought. For now we latch ^1da177e4c3f41 Linus Torvalds 2005-04-16 1507 options, received in the last packet, enqueued ^1da177e4c3f41 Linus Torvalds 2005-04-16 1508 by tcp. Feel free to propose better solution. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1509 --ANK (980728) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1510 */ ^1da177e4c3f41 Linus Torvalds 2005-04-16 1511 if (np->rxopt.all) 7450aaf61f0ae2 Eric Dumazet 2015-11-30 1512 opt_skb = skb_clone(skb, sk_gfp_mask(sk, GFP_ATOMIC)); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1513 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1514 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ 8f905c0e7354ef Eric Dumazet 2021-12-20 1515 struct dst_entry *dst; 8f905c0e7354ef Eric Dumazet 2021-12-20 1516 8f905c0e7354ef Eric Dumazet 2021-12-20 1517 dst = rcu_dereference_protected(sk->sk_rx_dst, 8f905c0e7354ef Eric Dumazet 2021-12-20 1518 lockdep_sock_is_held(sk)); 5d299f3d3c8a2f Eric Dumazet 2012-08-06 1519 bdeab991918663 Tom Herbert 2011-08-14 1520 sock_rps_save_rxhash(sk, skb); 3d97379a67486b Eric Dumazet 2014-11-11 1521 sk_mark_napi_id(sk, skb); 5d299f3d3c8a2f Eric Dumazet 2012-08-06 1522 if (dst) { 0c0a5ef809f915 Eric Dumazet 2021-10-25 1523 if (sk->sk_rx_dst_ifindex != skb->skb_iif || bbd807dfbf2050 Brian Vazquez 2021-02-01 1524 INDIRECT_CALL_1(dst->ops->check, ip6_dst_check, ef57c1610dd8fb Eric Dumazet 2021-10-25 1525 dst, sk->sk_rx_dst_cookie) == NULL) { 8f905c0e7354ef Eric Dumazet 2021-12-20 1526 RCU_INIT_POINTER(sk->sk_rx_dst, NULL); 5d299f3d3c8a2f Eric Dumazet 2012-08-06 1527 dst_release(dst); 5d299f3d3c8a2f Eric Dumazet 2012-08-06 1528 } 5d299f3d3c8a2f Eric Dumazet 2012-08-06 1529 } 5d299f3d3c8a2f Eric Dumazet 2012-08-06 1530 3d97d88e8091f3 Yafang Shao 2018-05-29 1531 tcp_rcv_established(sk, skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1532 if (opt_skb) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1533 goto ipv6_pktoptions; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1534 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1535 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 1536 12e25e1041d044 Eric Dumazet 2015-06-03 1537 if (tcp_checksum_complete(skb)) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1538 goto csum_err; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1539 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1540 if (sk->sk_state == TCP_LISTEN) { 079096f103faca Eric Dumazet 2015-10-02 1541 struct sock *nsk = tcp_v6_cookie_check(sk, skb); 079096f103faca Eric Dumazet 2015-10-02 1542 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1543 if (!nsk) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1544 goto discard; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1545 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1546 if (nsk != sk) { ^1da177e4c3f41 Linus Torvalds 2005-04-16 1547 if (tcp_child_process(sk, nsk, skb)) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1548 goto reset; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1549 if (opt_skb) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1550 __kfree_skb(opt_skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1551 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1552 } 47482f132a689a Neil Horman 2011-04-06 1553 } else bdeab991918663 Tom Herbert 2011-08-14 1554 sock_rps_save_rxhash(sk, skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1555 72ab4a86f7a260 Eric Dumazet 2015-09-29 @1556 if (tcp_rcv_state_process(sk, skb)) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1557 goto reset; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1558 if (opt_skb) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1559 goto ipv6_pktoptions; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1560 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1561 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1562 reset: cfb6eeb4c86059 YOSHIFUJI Hideaki 2006-11-14 1563 tcp_v6_send_reset(sk, skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1564 discard: ^1da177e4c3f41 Linus Torvalds 2005-04-16 1565 if (opt_skb) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1566 __kfree_skb(opt_skb); 8619663f7f150a Menglong Dong 2022-02-15 1567 kfree_skb_reason(skb, reason); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1568 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1569 csum_err: 8619663f7f150a Menglong Dong 2022-02-15 1570 reason = SKB_DROP_REASON_TCP_CSUM; 709c0314239992 Jakub Kicinski 2021-05-14 1571 trace_tcp_bad_csum(skb); c10d9310edf5aa Eric Dumazet 2016-04-29 1572 TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS); c10d9310edf5aa Eric Dumazet 2016-04-29 1573 TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1574 goto discard; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1575 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1576 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1577 ipv6_pktoptions: ^1da177e4c3f41 Linus Torvalds 2005-04-16 1578 /* Do you ask, what is it? ^1da177e4c3f41 Linus Torvalds 2005-04-16 1579 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1580 1. skb was enqueued by tcp. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1581 2. skb is added to tail of read queue, rather than out of order. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1582 3. socket is not in passive state. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1583 4. Finally, it really contains options, which user wants to receive. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1584 */ ^1da177e4c3f41 Linus Torvalds 2005-04-16 1585 tp = tcp_sk(sk); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1586 if (TCP_SKB_CB(opt_skb)->end_seq == tp->rcv_nxt && ^1da177e4c3f41 Linus Torvalds 2005-04-16 1587 !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) { 333fad5364d6b4 YOSHIFUJI Hideaki 2005-09-08 1588 if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo) 870c3151382c98 Eric Dumazet 2014-10-17 1589 np->mcast_oif = tcp_v6_iif(opt_skb); 333fad5364d6b4 YOSHIFUJI Hideaki 2005-09-08 1590 if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) 0660e03f6b18f1 Arnaldo Carvalho de Melo 2007-04-25 1591 np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit; 82e9f105a28006 Florent Fourcot 2013-12-08 1592 if (np->rxopt.bits.rxflow || np->rxopt.bits.rxtclass) 1397ed35f22d7c Florent Fourcot 2013-12-08 1593 np->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(opt_skb)); df3687ffc6653e Florent Fourcot 2014-01-17 1594 if (np->repflow) df3687ffc6653e Florent Fourcot 2014-01-17 1595 np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb)); a224772db8420e Eric Dumazet 2014-09-27 1596 if (ipv6_opt_accepted(sk, opt_skb, &TCP_SKB_CB(opt_skb)->header.h6)) { ^1da177e4c3f41 Linus Torvalds 2005-04-16 1597 skb_set_owner_r(opt_skb, sk); 8ce48623f0cf3d Eric Dumazet 2016-10-12 1598 tcp_v6_restore_cb(opt_skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1599 opt_skb = xchg(&np->pktoptions, opt_skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1600 } else { ^1da177e4c3f41 Linus Torvalds 2005-04-16 1601 __kfree_skb(opt_skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1602 opt_skb = xchg(&np->pktoptions, NULL); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1603 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 1604 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 1605 12c8691de30734 Eric Dumazet 2021-10-25 1606 consume_skb(opt_skb); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1607 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1608 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 1609 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org