tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 4f3d93c6eaff6b84e43b63e0d7a119c5920e1020 commit: d991bb1c8da842a2a0b9dc83b1005e655783f861 include/linux/compiler-gcc.h: sparse can do constant folding of __builtin_bswap*() date: 8 months ago config: i386-randconfig-s002-20211123 (https://download.01.org/0day-ci/archive/20220101/202201010449.pwZ9p571-lk...) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.4-dirty # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout d991bb1c8da842a2a0b9dc83b1005e655783f861 # save the config file to linux build tree mkdir build_dir make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 SHELL=/bin/bash 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 >>) drivers/net/usb/lan78xx.c:2963:29: sparse: sparse: cast to restricted __be16 drivers/net/usb/lan78xx.c:2963:27: sparse: expected restricted __wsum [usertype] csum drivers/net/usb/lan78xx.c:2963:27: sparse: got unsigned short [usertype] vim +2963 drivers/net/usb/lan78xx.c 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2949 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2950 static void lan78xx_rx_csum_offload(struct lan78xx_net *dev, 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2951 struct sk_buff *skb, 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2952 u32 rx_cmd_a, u32 rx_cmd_b) 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2953 { 9343ac87f2a4e0 Dave Stevenson 2018-06-25 2954 /* HW Checksum offload appears to be flawed if used when not stripping 9343ac87f2a4e0 Dave Stevenson 2018-06-25 2955 * VLAN headers. Drop back to S/W checksums under these conditions. 9343ac87f2a4e0 Dave Stevenson 2018-06-25 2956 */ 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2957 if (!(dev->net->features & NETIF_F_RXCSUM) || 9343ac87f2a4e0 Dave Stevenson 2018-06-25 2958 unlikely(rx_cmd_a & RX_CMD_A_ICSM_) || 9343ac87f2a4e0 Dave Stevenson 2018-06-25 2959 ((rx_cmd_a & RX_CMD_A_FVTG_) && 9343ac87f2a4e0 Dave Stevenson 2018-06-25 2960 !(dev->net->features & NETIF_F_HW_VLAN_CTAG_RX))) { 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2961 skb->ip_summed = CHECKSUM_NONE; 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2962 } else { 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 @2963 skb->csum = ntohs((u16)(rx_cmd_b >> RX_CMD_B_CSUM_SHIFT_)); 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2964 skb->ip_summed = CHECKSUM_COMPLETE; 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2965 } 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2966 } 55d7de9de6c30a Woojung.Huh(a)microchip.com 2015-07-30 2967 :::::: The code at line 2963 was first introduced by commit :::::: 55d7de9de6c30adce8d675c7ce513e283829c2ff Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver :::::: TO: Woojung.Huh(a)microchip.com <Woojung.Huh(a)microchip.com&gt; :::::: CC: David S. Miller <davem(a)davemloft.net&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org