Re: [PATCH] rethook: Use __rcu pointer for rethook::handler

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

Hi Masami,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.7-rc2 next-20231124]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Masami-Hiramatsu-Google/rethook-Use-__rcu-pointer-for-rethook-handler/20231124-090634
base:   linus/master
patch link:    https://lore.kernel.org/r/170078778632.209874.7893551840863388753.stgit%40devnote2
patch subject: [PATCH] rethook: Use __rcu pointer for rethook::handler
config: x86_64-randconfig-r113-20231124 (https://download.01.org/0day-ci/archive/20231124/202311241808.rv9ceuAh-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231124/202311241808.rv9ceuAh-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/202311241808.rv9ceuAh-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> kernel/trace/rethook.c:51:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> kernel/trace/rethook.c:51:9: sparse:    void ( [noderef] __rcu * )( ... )
>> kernel/trace/rethook.c:51:9: sparse:    void ( * )( ... )
   kernel/trace/rethook.c:66:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/rethook.c:66:9: sparse:    void ( [noderef] __rcu * )( ... )
   kernel/trace/rethook.c:66:9: sparse:    void ( * )( ... )
   kernel/trace/rethook.c:110:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/rethook.c:110:9: sparse:    void ( [noderef] __rcu * )( ... )
   kernel/trace/rethook.c:110:9: sparse:    void ( * )( ... )
   kernel/trace/rethook.c:140:19: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/rethook.c:140:19: sparse:    void ( [noderef] __rcu * )( ... )
   kernel/trace/rethook.c:140:19: sparse:    void ( * )( ... )
   kernel/trace/rethook.c:161:19: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/rethook.c:161:19: sparse:    void ( [noderef] __rcu * )( ... )
   kernel/trace/rethook.c:161:19: sparse:    void ( * )( ... )
   kernel/trace/rethook.c:305:27: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/rethook.c:305:27: sparse:    void ( [noderef] __rcu * )( ... )
   kernel/trace/rethook.c:305:27: sparse:    void ( * )( ... )

vim +51 kernel/trace/rethook.c

    40	
    41	/**
    42	 * rethook_stop() - Stop using a rethook.
    43	 * @rh: the struct rethook to stop.
    44	 *
    45	 * Stop using a rethook to prepare for freeing it. If you want to wait for
    46	 * all running rethook handler before calling rethook_free(), you need to
    47	 * call this first and wait RCU, and call rethook_free().
    48	 */
    49	void rethook_stop(struct rethook *rh)
    50	{
  > 51		rcu_assign_pointer(rh->handler, NULL);
    52	}
    53	

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