[mingo-tip:sched/headers 2150/2579] kernel/trace/trace_hwlat.c:175:6: warning: no previous prototype for 'trace_hwlat_callback'

[kernel test robot]

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git sched/headers
head:   49e1ec6c70a6eb4b7de9250a455b8b63eb42afbe
commit: b0a0ce86322929677661f28bec305c68815c387d [2150/2579] headers/deps: Remove <linux/hardirq.h> inclusions from headers that don't need it anymore
config: x86_64-randconfig-a011 (https://download.01.org/0day-ci/archive/20220420/202204202225.RdSY9Rvx-lkp@xxxxxxxxx/config)
compiler: gcc-11 (Debian 11.2.0-20) 11.2.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git/commit/?id=b0a0ce86322929677661f28bec305c68815c387d
        git remote add mingo-tip git://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git
        git fetch --no-tags mingo-tip sched/headers
        git checkout b0a0ce86322929677661f28bec305c68815c387d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/kernel/cpu/mtrr/ kernel/trace/

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

All warnings (new ones prefixed by >>):

>> kernel/trace/trace_hwlat.c:175:6: warning: no previous prototype for 'trace_hwlat_callback' [-Wmissing-prototypes]
     175 | void trace_hwlat_callback(bool enter)
         |      ^~~~~~~~~~~~~~~~~~~~


vim +/trace_hwlat_callback +175 kernel/trace/trace_hwlat.c

e7c15cd8a113335c Steven Rostedt (Red Hat    2016-06-23  174) 
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04 @175) void trace_hwlat_callback(bool enter)
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  176) {
f46b16520a087e89 Daniel Bristot de Oliveira 2021-06-22  177  	struct hwlat_kthread_data *kdata = get_cpu_data();
f46b16520a087e89 Daniel Bristot de Oliveira 2021-06-22  178  
f46b16520a087e89 Daniel Bristot de Oliveira 2021-06-22  179  	if (!kdata->kthread)
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  180) 		return;
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  181) 
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  182) 	/*
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  183) 	 * Currently trace_clock_local() calls sched_clock() and the
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  184) 	 * generic version is not NMI safe.
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  185) 	 */
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  186) 	if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  187) 		if (enter)
f46b16520a087e89 Daniel Bristot de Oliveira 2021-06-22  188  			kdata->nmi_ts_start = time_get();
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  189) 		else
f46b16520a087e89 Daniel Bristot de Oliveira 2021-06-22  190  			kdata->nmi_total_ts += time_get() - kdata->nmi_ts_start;
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  191) 	}
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  192) 
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  193) 	if (enter)
f46b16520a087e89 Daniel Bristot de Oliveira 2021-06-22  194  		kdata->nmi_count++;
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  195) }
7b2c86250122de31 Steven Rostedt (Red Hat    2016-08-04  196) 

:::::: The code at line 175 was first introduced by commit
:::::: 7b2c86250122de316cbab8754050622ead04af39 tracing: Add NMI tracing in hwlat detector

:::::: TO: Steven Rostedt (Red Hat) <rostedt@xxxxxxxxxxx>
:::::: CC: Steven Rostedt <rostedt@xxxxxxxxxxx>

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