[mac80211-next:vht-he 7/14] include/uapi/linux/kernel.h:12:49: warning: 'max_vht_nss' may be used uninitialized in this function

[mac80211-next:vht-he 7/14] include/uapi/linux/kernel.h:12:49: warning: 'max_vht_nss' may be used uninitialized in this function

[kbuild test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git vht-he
head:   fb4566483cf87f72333e1a3f65d99d9a24227b10
commit: 944d0b05ebf7bf2ae2cc4b7184e86d7cd3a9f18b [7/14] ieee80211: add new VHT capability fields/parsing
config: xtensa-allmodconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 4.9.0
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 944d0b05ebf7bf2ae2cc4b7184e86d7cd3a9f18b
        # save the attached .config to linux build tree
        make.cross ARCH=xtensa 

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 >>):

   In file included from include/linux/cache.h:4:0,
                    from include/linux/printk.h:8,
                    from include/linux/kernel.h:13,
                    from include/linux/skbuff.h:17,
                    from include/linux/if_ether.h:23,
                    from include/linux/etherdevice.h:25,
                    from net/wireless/util.c:9:
   net/wireless/util.c: In function 'ieee80211_get_vht_max_nss':
>> include/uapi/linux/kernel.h:12:49: warning: 'max_vht_nss' may be used uninitialized in this function [-Wmaybe-uninitialized]
    #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
                                                    ^
   net/wireless/util.c:1880:6: note: 'max_vht_nss' was declared here
     int max_vht_nss;
         ^

vim +/max_vht_nss +12 include/uapi/linux/kernel.h

607ca46e David Howells   2012-10-13   1  #ifndef _UAPI_LINUX_KERNEL_H
607ca46e David Howells   2012-10-13   2  #define _UAPI_LINUX_KERNEL_H
607ca46e David Howells   2012-10-13   3  
607ca46e David Howells   2012-10-13   4  #include <linux/sysinfo.h>
607ca46e David Howells   2012-10-13   5  
607ca46e David Howells   2012-10-13   6  /*
607ca46e David Howells   2012-10-13   7   * 'kernel.h' contains some often-used function prototypes etc
607ca46e David Howells   2012-10-13   8   */
607ca46e David Howells   2012-10-13   9  #define __ALIGN_KERNEL(x, a)		__ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
607ca46e David Howells   2012-10-13  10  #define __ALIGN_KERNEL_MASK(x, mask)	(((x) + (mask)) & ~(mask))
607ca46e David Howells   2012-10-13  11  
b5d3755a Nicolas Dichtel 2016-03-04 @12  #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
607ca46e David Howells   2012-10-13  13  
607ca46e David Howells   2012-10-13  14  #endif /* _UAPI_LINUX_KERNEL_H */

:::::: The code at line 12 was first introduced by commit
:::::: b5d3755a22e0cc4c369c0985aef0c52c2477c1e7 uapi: define DIV_ROUND_UP for userland

:::::: TO: Nicolas Dichtel <nicolas.dichtel@6wind.com>
:::::: CC: David S. Miller <davem@davemloft.net>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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