Re: [PATCH v2 net-next] net: usb: smsc95xx: stop lying about skb->truesize

[kernel test robot <lkp@intel.com>]

Hi Eric,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Eric-Dumazet/net-usb-smsc95xx-stop-lying-about-skb-truesize/20240508-155316
base:   net-next/main
patch link:    https://lore.kernel.org/r/20240508075159.1646031-1-edumazet%40google.com
patch subject: [PATCH v2 net-next] net: usb: smsc95xx: stop lying about skb->truesize
config: arc-randconfig-r132-20240509 (https://download.01.org/0day-ci/archive/20240509/202405091310.KvncIecx-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce: (https://download.01.org/0day-ci/archive/20240509/202405091310.KvncIecx-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405091310.KvncIecx-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/net/usb/smsc95xx.c:1815:19: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __wsum [usertype] csum @@     got unsigned short x @@
   drivers/net/usb/smsc95xx.c:1815:19: sparse:     expected restricted __wsum [usertype] csum
   drivers/net/usb/smsc95xx.c:1815:19: sparse:     got unsigned short x
   drivers/net/usb/smsc95xx.c: note: in included file (through include/net/checksum.h, include/linux/skbuff.h, include/net/net_namespace.h, ...):
   arch/arc/include/asm/checksum.h:27:26: sparse: sparse: restricted __wsum degrades to integer
   arch/arc/include/asm/checksum.h:27:36: sparse: sparse: restricted __wsum degrades to integer
   arch/arc/include/asm/checksum.h:29:11: sparse: sparse: bad assignment (-=) to restricted __wsum
   arch/arc/include/asm/checksum.h:30:16: sparse: sparse: restricted __wsum degrades to integer
   arch/arc/include/asm/checksum.h:30:18: sparse: sparse: incorrect type in return expression (different base types) @@     expected restricted __sum16 @@     got unsigned int @@
   arch/arc/include/asm/checksum.h:30:18: sparse:     expected restricted __sum16
   arch/arc/include/asm/checksum.h:30:18: sparse:     got unsigned int

vim +1815 drivers/net/usb/smsc95xx.c

  1810	
  1811	static void smsc95xx_rx_csum_offload(struct sk_buff *skb)
  1812	{
  1813		u16 *csum_ptr = (u16 *)(skb_tail_pointer(skb) - 2);
  1814	
> 1815		skb->csum = get_unaligned(csum_ptr);
  1816		skb->ip_summed = CHECKSUM_COMPLETE;
  1817		skb_trim(skb, skb->len - 2); /* remove csum */
  1818	}
  1819	

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