Hi John, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on net-next/master] [also build test WARNING on net/master sparc-next/master linus/master v5.8 next-20200813] [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/John-Ogness/af_packet-TPACKET_V3... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git bfdd5aaa54b0a44d9df550fe4c9db7e1470a11b8 config: i386-randconfig-s002-20200813 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.2-168-g9554805c-dirty # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) vim +/__packet_lookup_frame_in_block +1008 net/packet/af_packet.c f6fb8f100b80737 chetan loke 2011-08-19 1006 f6fb8f100b80737 chetan loke 2011-08-19 1007 /* Assumes caller has the sk->rx_queue.lock */ f6fb8f100b80737 chetan loke 2011-08-19 @1008 static void *__packet_lookup_frame_in_block(struct packet_sock *po, f6fb8f100b80737 chetan loke 2011-08-19 1009 struct sk_buff *skb, f6fb8f100b80737 chetan loke 2011-08-19 1010 unsigned int len f6fb8f100b80737 chetan loke 2011-08-19 1011 ) f6fb8f100b80737 chetan loke 2011-08-19 1012 { bc59ba399113fcb chetan loke 2011-08-25 1013 struct tpacket_kbdq_core *pkc; bc59ba399113fcb chetan loke 2011-08-25 1014 struct tpacket_block_desc *pbd; f6fb8f100b80737 chetan loke 2011-08-19 1015 char *curr, *end; f6fb8f100b80737 chetan loke 2011-08-19 1016 e3192690a3c8897 Joe Perches 2012-06-03 1017 pkc = GET_PBDQC_FROM_RB(&po->rx_ring); f6fb8f100b80737 chetan loke 2011-08-19 1018 pbd = GET_CURR_PBLOCK_DESC_FROM_CORE(pkc); f6fb8f100b80737 chetan loke 2011-08-19 1019 f6fb8f100b80737 chetan loke 2011-08-19 1020 /* Queue is frozen when user space is lagging behind */ f6fb8f100b80737 chetan loke 2011-08-19 1021 if (prb_queue_frozen(pkc)) { f6fb8f100b80737 chetan loke 2011-08-19 1022 /* f6fb8f100b80737 chetan loke 2011-08-19 1023 * Check if that last block which caused the queue to freeze, f6fb8f100b80737 chetan loke 2011-08-19 1024 * is still in_use by user-space. f6fb8f100b80737 chetan loke 2011-08-19 1025 */ 878cd3ba37f77de Rosen, Rami 2017-05-24 1026 if (prb_curr_blk_in_use(pbd)) { f6fb8f100b80737 chetan loke 2011-08-19 1027 /* Can't record this packet */ f6fb8f100b80737 chetan loke 2011-08-19 1028 return NULL; f6fb8f100b80737 chetan loke 2011-08-19 1029 } else { f6fb8f100b80737 chetan loke 2011-08-19 1030 /* f6fb8f100b80737 chetan loke 2011-08-19 1031 * Ok, the block was released by user-space. f6fb8f100b80737 chetan loke 2011-08-19 1032 * Now let's open that block. f6fb8f100b80737 chetan loke 2011-08-19 1033 * opening a block also thaws the queue. f6fb8f100b80737 chetan loke 2011-08-19 1034 * Thawing is a side effect. f6fb8f100b80737 chetan loke 2011-08-19 1035 */ f6fb8f100b80737 chetan loke 2011-08-19 1036 prb_open_block(pkc, pbd); f6fb8f100b80737 chetan loke 2011-08-19 1037 } f6fb8f100b80737 chetan loke 2011-08-19 1038 } f6fb8f100b80737 chetan loke 2011-08-19 1039 f6fb8f100b80737 chetan loke 2011-08-19 1040 smp_mb(); f6fb8f100b80737 chetan loke 2011-08-19 1041 curr = pkc->nxt_offset; f6fb8f100b80737 chetan loke 2011-08-19 1042 pkc->skb = skb; e3192690a3c8897 Joe Perches 2012-06-03 1043 end = (char *)pbd + pkc->kblk_size; f6fb8f100b80737 chetan loke 2011-08-19 1044 f6fb8f100b80737 chetan loke 2011-08-19 1045 /* first try the current block */ f6fb8f100b80737 chetan loke 2011-08-19 1046 if (curr+TOTAL_PKT_LEN_INCL_ALIGN(len) < end) { f6fb8f100b80737 chetan loke 2011-08-19 1047 prb_fill_curr_block(curr, pkc, pbd, len); f6fb8f100b80737 chetan loke 2011-08-19 1048 return (void *)curr; f6fb8f100b80737 chetan loke 2011-08-19 1049 } f6fb8f100b80737 chetan loke 2011-08-19 1050 f6fb8f100b80737 chetan loke 2011-08-19 1051 /* Ok, close the current block */ f6fb8f100b80737 chetan loke 2011-08-19 1052 prb_retire_current_block(pkc, po, 0); f6fb8f100b80737 chetan loke 2011-08-19 1053 f6fb8f100b80737 chetan loke 2011-08-19 1054 /* Now, try to dispatch the next block */ f6fb8f100b80737 chetan loke 2011-08-19 1055 curr = (char *)prb_dispatch_next_block(pkc, po); f6fb8f100b80737 chetan loke 2011-08-19 1056 if (curr) { f6fb8f100b80737 chetan loke 2011-08-19 1057 pbd = GET_CURR_PBLOCK_DESC_FROM_CORE(pkc); f6fb8f100b80737 chetan loke 2011-08-19 1058 prb_fill_curr_block(curr, pkc, pbd, len); f6fb8f100b80737 chetan loke 2011-08-19 1059 return (void *)curr; f6fb8f100b80737 chetan loke 2011-08-19 1060 } f6fb8f100b80737 chetan loke 2011-08-19 1061 f6fb8f100b80737 chetan loke 2011-08-19 1062 /* f6fb8f100b80737 chetan loke 2011-08-19 1063 * No free blocks are available.user_space hasn't caught up yet. f6fb8f100b80737 chetan loke 2011-08-19 1064 * Queue was just frozen and now this packet will get dropped. f6fb8f100b80737 chetan loke 2011-08-19 1065 */ f6fb8f100b80737 chetan loke 2011-08-19 1066 return NULL; f6fb8f100b80737 chetan loke 2011-08-19 1067 } f6fb8f100b80737 chetan loke 2011-08-19 1068 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org