Re: [PATCH net-next v2 12/12] net: homa: create Makefile and Kconfig

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

Hi John,

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/John-Ousterhout/net-homa-define-user-visible-API-for-Homa/20241112-074535
base:   net-next/main
patch link:    https://lore.kernel.org/r/20241111234006.5942-13-ouster%40cs.stanford.edu
patch subject: [PATCH net-next v2 12/12] net: homa: create Makefile and Kconfig
config: mips-allyesconfig (https://download.01.org/0day-ci/archive/20241112/202411121722.Oxq727h0-lkp@intel.com/config)
compiler: mips-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241112/202411121722.Oxq727h0-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/202411121722.Oxq727h0-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from arch/mips/include/asm/div64.h:89,
                    from include/linux/math.h:6,
                    from include/linux/kernel.h:27,
                    from include/linux/cpumask.h:11,
                    from arch/mips/include/asm/processor.h:15,
                    from arch/mips/include/asm/thread_info.h:16,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/current.h:6,
                    from ./arch/mips/include/generated/asm/current.h:1,
                    from include/linux/sched.h:12,
                    from include/linux/audit.h:12,
                    from net/homa/homa_impl.h:12,
                    from net/homa/homa_outgoing.c:7:
   net/homa/homa_outgoing.c: In function 'homa_new_data_packet':
>> include/asm-generic/div64.h:222:35: warning: comparison of distinct pointer types lacks a cast [-Wcompare-distinct-pointer-types]
     222 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
         |                                   ^~
   net/homa/homa_outgoing.c:108:9: note: in expansion of macro 'do_div'
     108 |         do_div(segs, max_seg_data);
         |         ^~~~~~
   In file included from arch/mips/include/asm/bug.h:5,
                    from include/linux/bug.h:5,
                    from net/homa/homa_impl.h:10:
>> include/asm-generic/div64.h:234:32: warning: right shift count >= width of type [-Wshift-count-overflow]
     234 |         } else if (likely(((n) >> 32) == 0)) {          \
         |                                ^~
   include/linux/compiler.h:76:45: note: in definition of macro 'likely'
      76 | # define likely(x)      __builtin_expect(!!(x), 1)
         |                                             ^
   net/homa/homa_outgoing.c:108:9: note: in expansion of macro 'do_div'
     108 |         do_div(segs, max_seg_data);
         |         ^~~~~~
   net/homa/homa_outgoing.c: In function 'homa_message_out_fill':
>> include/asm-generic/div64.h:222:35: warning: comparison of distinct pointer types lacks a cast [-Wcompare-distinct-pointer-types]
     222 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
         |                                   ^~
   net/homa/homa_outgoing.c:233:9: note: in expansion of macro 'do_div'
     233 |         do_div(segs_per_gso, max_seg_data);
         |         ^~~~~~
>> include/asm-generic/div64.h:234:32: warning: right shift count >= width of type [-Wshift-count-overflow]
     234 |         } else if (likely(((n) >> 32) == 0)) {          \
         |                                ^~
   include/linux/compiler.h:76:45: note: in definition of macro 'likely'
      76 | # define likely(x)      __builtin_expect(!!(x), 1)
         |                                             ^
   net/homa/homa_outgoing.c:233:9: note: in expansion of macro 'do_div'
     233 |         do_div(segs_per_gso, max_seg_data);
         |         ^~~~~~


vim +222 include/asm-generic/div64.h

^1da177e4c3f41 Linus Torvalds     2005-04-16  215  
^1da177e4c3f41 Linus Torvalds     2005-04-16  216  /* The unnecessary pointer compare is there
^1da177e4c3f41 Linus Torvalds     2005-04-16  217   * to check for type safety (n must be 64bit)
^1da177e4c3f41 Linus Torvalds     2005-04-16  218   */
^1da177e4c3f41 Linus Torvalds     2005-04-16  219  # define do_div(n,base) ({				\
^1da177e4c3f41 Linus Torvalds     2005-04-16  220  	uint32_t __base = (base);			\
^1da177e4c3f41 Linus Torvalds     2005-04-16  221  	uint32_t __rem;					\
^1da177e4c3f41 Linus Torvalds     2005-04-16 @222  	(void)(((typeof((n)) *)0) == ((uint64_t *)0));	\
911918aa7ef6f8 Nicolas Pitre      2015-11-02  223  	if (__builtin_constant_p(__base) &&		\
911918aa7ef6f8 Nicolas Pitre      2015-11-02  224  	    is_power_of_2(__base)) {			\
911918aa7ef6f8 Nicolas Pitre      2015-11-02  225  		__rem = (n) & (__base - 1);		\
911918aa7ef6f8 Nicolas Pitre      2015-11-02  226  		(n) >>= ilog2(__base);			\
c747ce4706190e Geert Uytterhoeven 2021-08-11  227  	} else if (__builtin_constant_p(__base) &&	\
461a5e51060c93 Nicolas Pitre      2015-10-30  228  		   __base != 0) {			\
461a5e51060c93 Nicolas Pitre      2015-10-30  229  		uint32_t __res_lo, __n_lo = (n);	\
461a5e51060c93 Nicolas Pitre      2015-10-30  230  		(n) = __div64_const32(n, __base);	\
461a5e51060c93 Nicolas Pitre      2015-10-30  231  		/* the remainder can be computed with 32-bit regs */ \
461a5e51060c93 Nicolas Pitre      2015-10-30  232  		__res_lo = (n);				\
461a5e51060c93 Nicolas Pitre      2015-10-30  233  		__rem = __n_lo - __res_lo * __base;	\
911918aa7ef6f8 Nicolas Pitre      2015-11-02 @234  	} else if (likely(((n) >> 32) == 0)) {		\
^1da177e4c3f41 Linus Torvalds     2005-04-16  235  		__rem = (uint32_t)(n) % __base;		\
^1da177e4c3f41 Linus Torvalds     2005-04-16  236  		(n) = (uint32_t)(n) / __base;		\
c747ce4706190e Geert Uytterhoeven 2021-08-11  237  	} else {					\
^1da177e4c3f41 Linus Torvalds     2005-04-16  238  		__rem = __div64_32(&(n), __base);	\
c747ce4706190e Geert Uytterhoeven 2021-08-11  239  	}						\
^1da177e4c3f41 Linus Torvalds     2005-04-16  240  	__rem;						\
^1da177e4c3f41 Linus Torvalds     2005-04-16  241   })
^1da177e4c3f41 Linus Torvalds     2005-04-16  242  

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