Hi Matteo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net/master]
[also build test WARNING on v5.1-rc7]
[cannot apply to next-20190429]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Matteo-Croce/proc-sysctl-add-shared-variables-for-range-check/20190430-065026
config: x86_64-randconfig-x000-201917 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   net/netfilter/ipvs/ip_vs_ctl.c: In function 'proc_do_defense_mode':
>> net/netfilter/ipvs/ip_vs_ctl.c:1664:28: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     struct netns_ipvs *ipvs = table->extra2;
                               ^~~~~

vim +/const +1664 net/netfilter/ipvs/ip_vs_ctl.c

749c42b6 net/netfilter/ipvs/ip_vs_ctl.c Julian Anastasov  2012-04-24  1659  
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1660  static int
fe2c6338 net/netfilter/ipvs/ip_vs_ctl.c Joe Perches       2013-06-11  1661  proc_do_defense_mode(struct ctl_table *table, int write,
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1662  		     void __user *buffer, size_t *lenp, loff_t *ppos)
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1663  {
717e917d net/netfilter/ipvs/ip_vs_ctl.c Eric W. Biederman 2015-09-21 @1664  	struct netns_ipvs *ipvs = table->extra2;
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1665  	int *valp = table->data;
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1666  	int val = *valp;
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1667  	int rc;
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1668  
8d65af78 net/netfilter/ipvs/ip_vs_ctl.c Alexey Dobriyan   2009-09-23  1669  	rc = proc_dointvec(table, write, buffer, lenp, ppos);
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1670  	if (write && (*valp != val)) {
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1671  		if ((*valp < 0) || (*valp > 3)) {
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1672  			/* Restore the correct value */
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1673  			*valp = val;
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1674  		} else {
717e917d net/netfilter/ipvs/ip_vs_ctl.c Eric W. Biederman 2015-09-21  1675  			update_defense_level(ipvs);
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1676  		}
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1677  	}
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1678  	return rc;
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1679  }
^1da177e net/ipv4/ipvs/ip_vs_ctl.c      Linus Torvalds    2005-04-16  1680  

:::::: The code at line 1664 was first introduced by commit
:::::: 717e917ddfa8db628041490eb44bce5815e947fd ipvs: Don't use current in proc_do_defense_mode

:::::: TO: Eric W. Biederman <ebiederm@xmission.com>
:::::: CC: Simon Horman <horms@verge.net.au>

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