Hi Xuan, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on net-next/main] url: https://github.com/intel-lab-lkp/linux/commits/Xuan-Zhuo/virtio_net-mergeable-xdp-put-old-page-immediately/20230322-110445 patch link: https://lore.kernel.org/r/20230322030308.16046-9-xuanzhuo%40linux.alibaba.com patch subject: [PATCH net-next 8/8] virtio_net: introduce receive_small_xdp() config: i386-randconfig-a002 (https://download.01.org/0day-ci/archive/20230323/202303230953.y0P1e1Fc-lkp@xxxxxxxxx/config) compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1) 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/intel-lab-lkp/linux/commit/6445923dc4c91e57f98b8356d0bd706e95dafaa1 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Xuan-Zhuo/virtio_net-mergeable-xdp-put-old-page-immediately/20230322-110445 git checkout 6445923dc4c91e57f98b8356d0bd706e95dafaa1 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/net/ If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Link: https://lore.kernel.org/oe-kbuild-all/202303230953.y0P1e1Fc-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> drivers/net/virtio_net.c:969:6: warning: variable 'buflen' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:78:22: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:990:22: note: uninitialized use occurs here xdp_init_buff(&xdp, buflen, &rq->xdp_rxq); ^~~~~~ drivers/net/virtio_net.c:969:2: note: remove the 'if' if its condition is always true if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:958:21: note: initialize the variable 'buflen' to silence this warning unsigned int buflen; ^ = 0 drivers/net/virtio_net.c:1428:6: warning: variable 'page' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:78:22: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1519:11: note: uninitialized use occurs here put_page(page); ^~~~ drivers/net/virtio_net.c:1428:2: note: remove the 'if' if its condition is always false if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1421:19: note: initialize the variable 'page' to silence this warning struct page *page; ^ = NULL drivers/net/virtio_net.c:1428:6: warning: variable 'num_buf' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:78:22: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1520:25: note: uninitialized use occurs here mergeable_buf_free(rq, num_buf, dev, stats); ^~~~~~~ drivers/net/virtio_net.c:1428:2: note: remove the 'if' if its condition is always false if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1422:13: note: initialize the variable 'num_buf' to silence this warning int num_buf; ^ = 0 3 warnings generated. vim +969 drivers/net/virtio_net.c 4941d472bf95b4 Jason Wang 2017-07-19 941 6445923dc4c91e Xuan Zhuo 2023-03-22 942 static struct sk_buff *receive_small_xdp(struct net_device *dev, bb91accf27335c Jason Wang 2016-12-23 943 struct virtnet_info *vi, bb91accf27335c Jason Wang 2016-12-23 944 struct receive_queue *rq, 6445923dc4c91e Xuan Zhuo 2023-03-22 945 struct bpf_prog *xdp_prog, 6445923dc4c91e Xuan Zhuo 2023-03-22 946 void *buf, 6445923dc4c91e Xuan Zhuo 2023-03-22 947 void *ctx, 186b3c998c50fc Jason Wang 2017-09-19 948 unsigned int len, 7d9d60fd4ab696 Toshiaki Makita 2018-07-23 949 unsigned int *xdp_xmit, d46eeeaf99bcfa Jason Wang 2018-07-31 950 struct virtnet_rq_stats *stats) f121159d72091f Michael S. Tsirkin 2013-11-28 951 { 4941d472bf95b4 Jason Wang 2017-07-19 952 unsigned int xdp_headroom = (unsigned long)ctx; f6b10209b90d48 Jason Wang 2017-02-21 953 unsigned int header_offset = VIRTNET_RX_PAD + xdp_headroom; f6b10209b90d48 Jason Wang 2017-02-21 954 unsigned int headroom = vi->hdr_len + header_offset; 6445923dc4c91e Xuan Zhuo 2023-03-22 955 struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset; 4941d472bf95b4 Jason Wang 2017-07-19 956 struct page *page = virt_to_head_page(buf); 4941d472bf95b4 Jason Wang 2017-07-19 957 struct page *xdp_page; 6445923dc4c91e Xuan Zhuo 2023-03-22 958 unsigned int buflen; 0354e4d19cd5de John Fastabend 2017-02-02 959 struct xdp_buff xdp; 6445923dc4c91e Xuan Zhuo 2023-03-22 960 struct sk_buff *skb; 6445923dc4c91e Xuan Zhuo 2023-03-22 961 unsigned int delta = 0; 6445923dc4c91e Xuan Zhuo 2023-03-22 962 unsigned int metasize = 0; f6b10209b90d48 Jason Wang 2017-02-21 963 void *orig_data; bb91accf27335c Jason Wang 2016-12-23 964 u32 act; bb91accf27335c Jason Wang 2016-12-23 965 95dbe9e7b3720e Jesper Dangaard Brouer 2018-02-20 966 if (unlikely(hdr->hdr.gso_type)) bb91accf27335c Jason Wang 2016-12-23 967 goto err_xdp; 0354e4d19cd5de John Fastabend 2017-02-02 968 4941d472bf95b4 Jason Wang 2017-07-19 @969 if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) { 4941d472bf95b4 Jason Wang 2017-07-19 970 int offset = buf - page_address(page) + header_offset; 4941d472bf95b4 Jason Wang 2017-07-19 971 unsigned int tlen = len + vi->hdr_len; 981f14d42a7f16 Heng Qi 2023-01-31 972 int num_buf = 1; 4941d472bf95b4 Jason Wang 2017-07-19 973 4941d472bf95b4 Jason Wang 2017-07-19 974 xdp_headroom = virtnet_get_headroom(vi); 4941d472bf95b4 Jason Wang 2017-07-19 975 header_offset = VIRTNET_RX_PAD + xdp_headroom; 4941d472bf95b4 Jason Wang 2017-07-19 976 headroom = vi->hdr_len + header_offset; 4941d472bf95b4 Jason Wang 2017-07-19 977 buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) + 4941d472bf95b4 Jason Wang 2017-07-19 978 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); 4941d472bf95b4 Jason Wang 2017-07-19 979 xdp_page = xdp_linearize_page(rq, &num_buf, page, 4941d472bf95b4 Jason Wang 2017-07-19 980 offset, header_offset, 4941d472bf95b4 Jason Wang 2017-07-19 981 &tlen); 4941d472bf95b4 Jason Wang 2017-07-19 982 if (!xdp_page) 4941d472bf95b4 Jason Wang 2017-07-19 983 goto err_xdp; 4941d472bf95b4 Jason Wang 2017-07-19 984 4941d472bf95b4 Jason Wang 2017-07-19 985 buf = page_address(xdp_page); 4941d472bf95b4 Jason Wang 2017-07-19 986 put_page(page); 4941d472bf95b4 Jason Wang 2017-07-19 987 page = xdp_page; 4941d472bf95b4 Jason Wang 2017-07-19 988 } 4941d472bf95b4 Jason Wang 2017-07-19 989 43b5169d8355cc Lorenzo Bianconi 2020-12-22 990 xdp_init_buff(&xdp, buflen, &rq->xdp_rxq); be9df4aff65f18 Lorenzo Bianconi 2020-12-22 991 xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len, be9df4aff65f18 Lorenzo Bianconi 2020-12-22 992 xdp_headroom, len, true); f6b10209b90d48 Jason Wang 2017-02-21 993 orig_data = xdp.data; 4249e276b1ab30 Xuan Zhuo 2023-03-22 994 4249e276b1ab30 Xuan Zhuo 2023-03-22 995 act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats); 0354e4d19cd5de John Fastabend 2017-02-02 996 bb91accf27335c Jason Wang 2016-12-23 997 switch (act) { 4249e276b1ab30 Xuan Zhuo 2023-03-22 998 case VIRTNET_XDP_RES_PASS: 2de2f7f40ef923 John Fastabend 2017-02-02 999 /* Recalculate length in case bpf program changed it */ f6b10209b90d48 Jason Wang 2017-02-21 1000 delta = orig_data - xdp.data; 6870de435b90c0 Nikita V. Shirokov 2018-04-17 1001 len = xdp.data_end - xdp.data; 503d539a6e417b Yuya Kusakabe 2020-02-25 1002 metasize = xdp.data - xdp.data_meta; bb91accf27335c Jason Wang 2016-12-23 1003 break; 4249e276b1ab30 Xuan Zhuo 2023-03-22 1004 4249e276b1ab30 Xuan Zhuo 2023-03-22 1005 case VIRTNET_XDP_RES_CONSUMED: bb91accf27335c Jason Wang 2016-12-23 1006 goto xdp_xmit; 4249e276b1ab30 Xuan Zhuo 2023-03-22 1007 4249e276b1ab30 Xuan Zhuo 2023-03-22 1008 case VIRTNET_XDP_RES_DROP: bb91accf27335c Jason Wang 2016-12-23 1009 goto err_xdp; bb91accf27335c Jason Wang 2016-12-23 1010 } bb91accf27335c Jason Wang 2016-12-23 1011 f6b10209b90d48 Jason Wang 2017-02-21 1012 skb = build_skb(buf, buflen); 053c9e18c6f9cf Wenliang Wang 2021-12-16 1013 if (!skb) f6b10209b90d48 Jason Wang 2017-02-21 1014 goto err; 6445923dc4c91e Xuan Zhuo 2023-03-22 1015 f6b10209b90d48 Jason Wang 2017-02-21 1016 skb_reserve(skb, headroom - delta); 6870de435b90c0 Nikita V. Shirokov 2018-04-17 1017 skb_put(skb, len); 503d539a6e417b Yuya Kusakabe 2020-02-25 1018 if (metasize) 503d539a6e417b Yuya Kusakabe 2020-02-25 1019 skb_metadata_set(skb, metasize); 503d539a6e417b Yuya Kusakabe 2020-02-25 1020 f121159d72091f Michael S. Tsirkin 2013-11-28 1021 return skb; bb91accf27335c Jason Wang 2016-12-23 1022 bb91accf27335c Jason Wang 2016-12-23 1023 err_xdp: d46eeeaf99bcfa Jason Wang 2018-07-31 1024 stats->xdp_drops++; 053c9e18c6f9cf Wenliang Wang 2021-12-16 1025 err: d46eeeaf99bcfa Jason Wang 2018-07-31 1026 stats->drops++; 4941d472bf95b4 Jason Wang 2017-07-19 1027 put_page(page); bb91accf27335c Jason Wang 2016-12-23 1028 xdp_xmit: bb91accf27335c Jason Wang 2016-12-23 1029 return NULL; f121159d72091f Michael S. Tsirkin 2013-11-28 1030 } f121159d72091f Michael S. Tsirkin 2013-11-28 1031 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests
