Hi Florian,

I love your patch! Perhaps something to improve:

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

url:    
https://github.com/0day-ci/linux/commits/Florian-Westphal/xfrm-remove-xfrm-replay-indirections/20200624-035102
base:   https://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next.git 
master
config: mips-malta_defconfig (attached as .config)
compiler: mipsel-linux-gcc (GCC) 9.3.0
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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross 
ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

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 >>):

   net/xfrm/xfrm_replay.c: In function 'xfrm_replay_advance':
>> net/xfrm/xfrm_replay.c:519:13: warning: 'seq' may be used uninitialized in 
>> this function [-Wmaybe-uninitialized]
     519 |  if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
         |      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
   net/xfrm/xfrm_replay.c:509:17: note: 'seq' was declared here
     509 |  u32 diff, pos, seq, seq_hi;
         |                 ^~~

vim +/seq +519 net/xfrm/xfrm_replay.c

3b59df46a449ec9 Steffen Klassert 2012-09-04  504  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  505  static void 
xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
2cd084678fc1eb7 Steffen Klassert 2011-03-08  506  {
2cd084678fc1eb7 Steffen Klassert 2011-03-08  507        unsigned int bitnr, nr, 
i;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  508        int wrap;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  509        u32 diff, pos, seq, 
seq_hi;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  510        struct 
xfrm_replay_state_esn *replay_esn = x->replay_esn;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  511  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  512        if 
(!replay_esn->replay_window)
2cd084678fc1eb7 Steffen Klassert 2011-03-08  513                return;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  514  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  515        pos = (replay_esn->seq 
- 1) % replay_esn->replay_window;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  516        seq_hi = 
xfrm_replay_seqhi(x, net_seq);
2cd084678fc1eb7 Steffen Klassert 2011-03-08  517        wrap = seq_hi - 
replay_esn->seq_hi;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  518  
2cd084678fc1eb7 Steffen Klassert 2011-03-08 @519        if ((!wrap && seq > 
replay_esn->seq) || wrap > 0) {
2cd084678fc1eb7 Steffen Klassert 2011-03-08  520                if 
(likely(!wrap))
2cd084678fc1eb7 Steffen Klassert 2011-03-08  521                        diff = 
seq - replay_esn->seq;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  522                else
2cd084678fc1eb7 Steffen Klassert 2011-03-08  523                        diff = 
~replay_esn->seq + seq + 1;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  524  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  525                if (diff < 
replay_esn->replay_window) {
2cd084678fc1eb7 Steffen Klassert 2011-03-08  526                        for (i 
= 1; i < diff; i++) {
2cd084678fc1eb7 Steffen Klassert 2011-03-08  527                                
bitnr = (pos + i) % replay_esn->replay_window;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  528                                
nr = bitnr >> 5;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  529                                
bitnr = bitnr & 0x1F;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  530                                
replay_esn->bmp[nr] &=  ~(1U << bitnr);
2cd084678fc1eb7 Steffen Klassert 2011-03-08  531                        }
2cd084678fc1eb7 Steffen Klassert 2011-03-08  532                } else {
e756682c8baa47d Steffen Klassert 2011-06-05  533                        nr = 
(replay_esn->replay_window - 1) >> 5;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  534                        for (i 
= 0; i <= nr; i++)
2cd084678fc1eb7 Steffen Klassert 2011-03-08  535                                
replay_esn->bmp[i] = 0;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  536                }
2cd084678fc1eb7 Steffen Klassert 2011-03-08  537  
1d9743745bf5ba3 Steffen Klassert 2011-10-11  538                bitnr = (pos + 
diff) % replay_esn->replay_window;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  539                replay_esn->seq 
= seq;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  540  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  541                if 
(unlikely(wrap > 0))
2cd084678fc1eb7 Steffen Klassert 2011-03-08  542                        
replay_esn->seq_hi++;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  543        } else {
2cd084678fc1eb7 Steffen Klassert 2011-03-08  544                diff = 
replay_esn->seq - seq;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  545  
1d9743745bf5ba3 Steffen Klassert 2011-10-11  546                if (pos >= diff)
2cd084678fc1eb7 Steffen Klassert 2011-03-08  547                        bitnr = 
(pos - diff) % replay_esn->replay_window;
1d9743745bf5ba3 Steffen Klassert 2011-10-11  548                else
2cd084678fc1eb7 Steffen Klassert 2011-03-08  549                        bitnr = 
replay_esn->replay_window - (diff - pos);
1d9743745bf5ba3 Steffen Klassert 2011-10-11  550        }
1d9743745bf5ba3 Steffen Klassert 2011-10-11  551  
50bd870a9e5cca9 Yossef Efraim    2018-01-14  552        
xfrm_dev_state_advance_esn(x);
50bd870a9e5cca9 Yossef Efraim    2018-01-14  553  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  554        nr = bitnr >> 5;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  555        bitnr = bitnr & 0x1F;
2cd084678fc1eb7 Steffen Klassert 2011-03-08  556        replay_esn->bmp[nr] |= 
(1U << bitnr);
2cd084678fc1eb7 Steffen Klassert 2011-03-08  557  
2cd084678fc1eb7 Steffen Klassert 2011-03-08  558        if 
(xfrm_aevent_is_on(xs_net(x)))
f7d9410c27544ca Florian Westphal 2020-06-23  559                
xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
2cd084678fc1eb7 Steffen Klassert 2011-03-08  560  }
2cd084678fc1eb7 Steffen Klassert 2011-03-08  561  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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