Hi David, [auto build test WARNING on net-next/master] [also build test WARNING on next-20170817] [cannot apply to v4.13-rc5] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/David-Lamparter/bridge-learn-dst-metadata-in-FDB/20170820-001849 config: xtensa-allmodconfig (attached as .config) compiler: xtensa-linux-gcc (GCC) 4.9.0 reproduce: wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree make.cross ARCH=xtensa Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings All warnings (new ones prefixed by >>): net/mpls/af_mpls.c: In function 'mpls_rt_xmit': >> net/mpls/af_mpls.c:452:45: warning: 'out_dev' may be used uninitialized in this function [-Wmaybe-uninitialized] out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL; ^ vim +/out_dev +452 net/mpls/af_mpls.c 679ee57f David Lamparter 2017-08-16 379 679ee57f David Lamparter 2017-08-16 380 int mpls_rt_xmit(struct sk_buff *skb, struct mpls_route *rt, 679ee57f David Lamparter 2017-08-16 381 struct mpls_entry_decoded dec) 679ee57f David Lamparter 2017-08-16 382 { 679ee57f David Lamparter 2017-08-16 383 struct mpls_nh *nh; 679ee57f David Lamparter 2017-08-16 384 struct net_device *out_dev; 679ee57f David Lamparter 2017-08-16 385 struct mpls_dev *out_mdev; 679ee57f David Lamparter 2017-08-16 386 unsigned int hh_len; 679ee57f David Lamparter 2017-08-16 387 unsigned int new_header_size; 679ee57f David Lamparter 2017-08-16 388 unsigned int mtu; 679ee57f David Lamparter 2017-08-16 389 int err; 679ee57f David Lamparter 2017-08-16 390 679ee57f David Lamparter 2017-08-16 391 nh = mpls_select_multipath(rt, skb); 679ee57f David Lamparter 2017-08-16 392 if (!nh) 679ee57f David Lamparter 2017-08-16 393 goto tx_err; 679ee57f David Lamparter 2017-08-16 394 27d69105 Robert Shearman 2017-01-16 395 /* Find the output device */ 27d69105 Robert Shearman 2017-01-16 396 out_dev = rcu_dereference(nh->nh_dev); 27d69105 Robert Shearman 2017-01-16 397 if (!mpls_output_possible(out_dev)) 27d69105 Robert Shearman 2017-01-16 398 goto tx_err; 27d69105 Robert Shearman 2017-01-16 399 0189197f Eric W. Biederman 2015-03-03 400 /* Verify the destination can hold the packet */ f8efb73c Roopa Prabhu 2015-10-23 401 new_header_size = mpls_nh_header_size(nh); 0189197f Eric W. Biederman 2015-03-03 402 mtu = mpls_dev_mtu(out_dev); 0189197f Eric W. Biederman 2015-03-03 403 if (mpls_pkt_too_big(skb, mtu - new_header_size)) 27d69105 Robert Shearman 2017-01-16 404 goto tx_err; 0189197f Eric W. Biederman 2015-03-03 405 0189197f Eric W. Biederman 2015-03-03 406 hh_len = LL_RESERVED_SPACE(out_dev); 0189197f Eric W. Biederman 2015-03-03 407 if (!out_dev->header_ops) 0189197f Eric W. Biederman 2015-03-03 408 hh_len = 0; 0189197f Eric W. Biederman 2015-03-03 409 0189197f Eric W. Biederman 2015-03-03 410 /* Ensure there is enough space for the headers in the skb */ 0189197f Eric W. Biederman 2015-03-03 411 if (skb_cow(skb, hh_len + new_header_size)) 27d69105 Robert Shearman 2017-01-16 412 goto tx_err; 0189197f Eric W. Biederman 2015-03-03 413 0189197f Eric W. Biederman 2015-03-03 414 skb->dev = out_dev; 0189197f Eric W. Biederman 2015-03-03 415 skb->protocol = htons(ETH_P_MPLS_UC); 0189197f Eric W. Biederman 2015-03-03 416 0189197f Eric W. Biederman 2015-03-03 417 if (unlikely(!new_header_size && dec.bos)) { 0189197f Eric W. Biederman 2015-03-03 418 /* Penultimate hop popping */ 5b441ac8 Robert Shearman 2017-03-10 419 if (!mpls_egress(dev_net(out_dev), rt, skb, dec)) 679ee57f David Lamparter 2017-08-16 420 goto tx_err; 0189197f Eric W. Biederman 2015-03-03 421 } else { 679ee57f David Lamparter 2017-08-16 422 struct mpls_shim_hdr *hdr; 0189197f Eric W. Biederman 2015-03-03 423 bool bos; 0189197f Eric W. Biederman 2015-03-03 424 int i; 0189197f Eric W. Biederman 2015-03-03 425 skb_push(skb, new_header_size); 0189197f Eric W. Biederman 2015-03-03 426 skb_reset_network_header(skb); 0189197f Eric W. Biederman 2015-03-03 427 /* Push the new labels */ 0189197f Eric W. Biederman 2015-03-03 428 hdr = mpls_hdr(skb); 0189197f Eric W. Biederman 2015-03-03 429 bos = dec.bos; f8efb73c Roopa Prabhu 2015-10-23 430 for (i = nh->nh_labels - 1; i >= 0; i--) { f8efb73c Roopa Prabhu 2015-10-23 431 hdr[i] = mpls_entry_encode(nh->nh_label[i], f8efb73c Roopa Prabhu 2015-10-23 432 dec.ttl, 0, bos); 0189197f Eric W. Biederman 2015-03-03 433 bos = false; 0189197f Eric W. Biederman 2015-03-03 434 } 0189197f Eric W. Biederman 2015-03-03 435 } 0189197f Eric W. Biederman 2015-03-03 436 27d69105 Robert Shearman 2017-01-16 437 mpls_stats_inc_outucastpkts(out_dev, skb); 27d69105 Robert Shearman 2017-01-16 438 eb7809f0 Robert Shearman 2015-12-10 439 /* If via wasn't specified then send out using device address */ eb7809f0 Robert Shearman 2015-12-10 440 if (nh->nh_via_table == MPLS_NEIGH_TABLE_UNSPEC) eb7809f0 Robert Shearman 2015-12-10 441 err = neigh_xmit(NEIGH_LINK_TABLE, out_dev, eb7809f0 Robert Shearman 2015-12-10 442 out_dev->dev_addr, skb); eb7809f0 Robert Shearman 2015-12-10 443 else eb7809f0 Robert Shearman 2015-12-10 444 err = neigh_xmit(nh->nh_via_table, out_dev, eb7809f0 Robert Shearman 2015-12-10 445 mpls_nh_via(rt, nh), skb); 0189197f Eric W. Biederman 2015-03-03 446 if (err) 0189197f Eric W. Biederman 2015-03-03 447 net_dbg_ratelimited("%s: packet transmission failed: %d\n", 0189197f Eric W. Biederman 2015-03-03 448 __func__, err); 0189197f Eric W. Biederman 2015-03-03 449 return 0; 0189197f Eric W. Biederman 2015-03-03 450 27d69105 Robert Shearman 2017-01-16 451 tx_err: 27d69105 Robert Shearman 2017-01-16 @452 out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL; 27d69105 Robert Shearman 2017-01-16 453 if (out_mdev) 27d69105 Robert Shearman 2017-01-16 454 MPLS_INC_STATS(out_mdev, tx_errors); 679ee57f David Lamparter 2017-08-16 455 return -1; 0189197f Eric W. Biederman 2015-03-03 456 } 0189197f Eric W. Biederman 2015-03-03 457 :::::: The code at line 452 was first introduced by commit :::::: 27d691056bde4a6feca5e83fd92b787332c46302 mpls: Packet stats :::::: TO: Robert Shearman :::::: CC: David S. Miller --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation