Hi Song, I love your patch! Perhaps something to improve: [auto build test WARNING on bpf-next/master] url: https://github.com/intel-lab-lkp/linux/commits/Song-Liu/ftrace-host-klp-and-bpf-trampoline-together/20220718-135652 base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master config: x86_64-randconfig-a004 (https://download.01.org/0day-ci/archive/20220718/202207181552.VuKfz9zg-lkp@xxxxxxxxx/config) compiler: gcc-11 (Debian 11.3.0-3) 11.3.0 reproduce (this is a W=1 build): # https://github.com/intel-lab-lkp/linux/commit/9ef1ec8cb818d8ca70887c8c123f2d579384a6c6 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Song-Liu/ftrace-host-klp-and-bpf-trampoline-together/20220718-135652 git checkout 9ef1ec8cb818d8ca70887c8c123f2d579384a6c6 # save the config file mkdir build_dir && cp config build_dir/.config make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/trace/ If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): kernel/trace/ftrace.c: In function 'register_ftrace_function': >> kernel/trace/ftrace.c:8197:14: warning: variable 'direct_mutex_locked' set but not used [-Wunused-but-set-variable] 8197 | bool direct_mutex_locked = false; | ^~~~~~~~~~~~~~~~~~~ vim +/direct_mutex_locked +8197 kernel/trace/ftrace.c 8182 8183 /** 8184 * register_ftrace_function - register a function for profiling 8185 * @ops: ops structure that holds the function for profiling. 8186 * 8187 * Register a function to be called by all functions in the 8188 * kernel. 8189 * 8190 * Note: @ops->func and all the functions it calls must be labeled 8191 * with "notrace", otherwise it will go into a 8192 * recursive loop. 8193 */ 8194 int register_ftrace_function(struct ftrace_ops *ops) 8195 __releases(&direct_mutex) 8196 { > 8197 bool direct_mutex_locked = false; 8198 int ret; 8199 8200 ftrace_ops_init(ops); 8201 8202 ret = prepare_direct_functions_for_ipmodify(ops); 8203 if (ret < 0) 8204 return ret; 8205 else if (ret == 1) 8206 direct_mutex_locked = true; 8207 8208 mutex_lock(&ftrace_lock); 8209 8210 ret = ftrace_startup(ops, 0); 8211 8212 mutex_unlock(&ftrace_lock); 8213 -- 0-DAY CI Kernel Test Service https://01.org/lkp
