Re: [PATCH v2] io_uring: Add support for napi_busy_poll

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

Hi Olivier,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[cannot apply to v5.17-rc5 next-20220225]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Olivier-Langlois/io_uring-Add-support-for-napi_busy_poll/20220228-012140
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2293be58d6a18cab800e25e42081bacb75c05752
config: arc-randconfig-r043-20220227 (https://download.01.org/0day-ci/archive/20220228/202202280400.HHUsYqhX-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 11.2.0
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
        # https://github.com/0day-ci/linux/commit/65e72f78c66272f7cf0e87dfeef88f5b79de2d91
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Olivier-Langlois/io_uring-Add-support-for-napi_busy_poll/20220228-012140
        git checkout 65e72f78c66272f7cf0e87dfeef88f5b79de2d91
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arc SHELL=/bin/bash

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

All warnings (new ones prefixed by >>):

   fs/io_uring.c: In function '__io_submit_flush_completions':
   fs/io_uring.c:2531:40: warning: variable 'prev' set but not used [-Wunused-but-set-variable]
    2531 |         struct io_wq_work_node *node, *prev;
         |                                        ^~~~
   In file included from ./arch/arc/include/generated/asm/div64.h:1,
                    from include/linux/math.h:5,
                    from include/linux/kernel.h:25,
                    from fs/io_uring.c:42:
   fs/io_uring.c: In function 'io_adjust_busy_loop_timeout':
>> include/asm-generic/div64.h:222:35: warning: comparison of distinct pointer types lacks a cast
     222 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
         |                                   ^~
   fs/io_uring.c:7840:17: note: in expansion of macro 'do_div'
    7840 |                 do_div(to, 1000);
         |                 ^~~~~~


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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