Subject: Re: [PATCH 1/2] perf/core: Adding capability to disable PMUs event multiplexing

From: kbuild test robot <[email-masked]>
Date: Fri, 8 Nov 2019 07:17:16 +0800

Hi Ganapatrao,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on arm-soc/for-next]
[also build test WARNING on v5.4-rc6 next-20191107]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Ganapatrao-Prabhakerrao-Kulkarni/perf-core-Adding-capability-to-disable-PMUs-event-multiplexing/20191108-054345
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc.git for-next
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.4.0-14) 7.4.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email-masked]>

All warnings (new ones prefixed by >>):

   kernel/events/core.c: In function '__perf_mux_hrtimer_init':
>> kernel/events/core.c:1097:10: warning: 'return' with a value, in function returning void
      return 0;
             ^
   kernel/events/core.c:1085:13: note: declared here
    static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
                ^~~~~~~~~~~~~~~~~~~~~~~

vim +/return +1097 kernel/events/core.c

  1084	
  1085	static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
  1086	{
  1087		struct hrtimer *timer = &cpuctx->hrtimer;
  1088		struct pmu *pmu = cpuctx->ctx.pmu;
  1089		u64 interval;
  1090	
  1091		/* no multiplexing needed for SW PMU */
  1092		if (pmu->task_ctx_nr == perf_sw_context)
  1093			return;
  1094	
  1095		/* No PMU support */
  1096		if (pmu->capabilities & PERF_PMU_CAP_NO_MUX_EVENTS)
> 1097			return 0;
  1098	
  1099		/*
  1100		 * check default is sane, if not set then force to
  1101		 * default interval (1/tick)
  1102		 */
  1103		interval = pmu->hrtimer_interval_ms;
  1104		if (interval < 1)
  1105			interval = pmu->hrtimer_interval_ms = PERF_CPU_HRTIMER;
  1106	
  1107		cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
  1108	
  1109		raw_spin_lock_init(&cpuctx->hrtimer_lock);
  1110		hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
  1111		timer->function = perf_mux_hrtimer_handler;
  1112	}
  1113	

---
0-DAY kernel test infrastructure                 Open Source Technology Center
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