Re: [PATCH V3 net-next] net: hns: Fix to conditionally convey RX checksum flag to stack

Hi Salil,

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

url:    https://github.com/0day-ci/linux/commits/Salil-Mehta/net-hns-Fix-to-conditionally-convey-RX-checksum-flag-to-stack/20161206-022948
config: i386-allmodconfig (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

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 >>):

   drivers/net/ethernet/hisilicon/hns/hns_enet.c: In function 'hns_nic_rx_poll_one':

quoted

drivers/net/ethernet/hisilicon/hns/hns_enet.c:606:5: warning: 'l3id' may be used uninitialized in this function [-Wmaybe-uninitialized]

     if ((l3id != HNS_RX_FLAG_L3ID_IPV4) && (l3id != HNS_RX_FLAG_L3ID_IPV6))
        ^
   drivers/net/ethernet/hisilicon/hns/hns_enet.c:573:6: note: 'l3id' was declared here
     u32 l3id;
         ^~~~

quoted

drivers/net/ethernet/hisilicon/hns/hns_enet.c:618:37: warning: 'l4id' may be used uninitialized in this function [-Wmaybe-uninitialized]

     if ((l4id != HNS_RX_FLAG_L4ID_TCP) &&
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
         (l4id != HNS_RX_FLAG_L4ID_UDP) &&
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   drivers/net/ethernet/hisilicon/hns/hns_enet.c:574:6: note: 'l4id' was declared here
     u32 l4id;
         ^~~~

vim +/l3id +606 drivers/net/ethernet/hisilicon/hns/hns_enet.c

   600		 * checksum or any other L3/L4 error, we will not (cannot) convey
   601		 * checksum status for such cases to upper stack and will not maintain
   602		 * the RX L3/L4 checksum counters as well.
   603		 */
   604	
   605		/*  check L3 protocol for which checksum is supported */
 > 606		if ((l3id != HNS_RX_FLAG_L3ID_IPV4) && (l3id != HNS_RX_FLAG_L3ID_IPV6))
   607			return;
   608	
   609		/* check for any(not just checksum)flagged L3 protocol errors */
   610		if (unlikely(hnae_get_bit(flag, HNS_RXD_L3E_B)))
   611			return;
   612	
   613		/* we do not support checksum of fragmented packets */
   614		if (unlikely(hnae_get_bit(flag, HNS_RXD_FRAG_B)))
   615			return;
   616	
   617		/*  check L4 protocol for which checksum is supported */
 > 618		if ((l4id != HNS_RX_FLAG_L4ID_TCP) &&
   619		    (l4id != HNS_RX_FLAG_L4ID_UDP) &&
   620		    (l4id != HNS_RX_FLAG_L4ID_SCTP))
   621			return;

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