tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git hrtimer
head:   16c372aeaca31d5d9d998466e75e845a2926685f
commit: 6161421a8190f07b3c0a52c0b62c8b3f51de6ddf [8/12] hrtimer: Avoid reprogramming when callback is running
config: um-x86_64_defconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/commit/?id=6161421a8190f07b3c0a52c0b62c8b3f51de6ddf
        git remote add tglx-devel https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git
        git fetch --no-tags tglx-devel hrtimer
        git checkout 6161421a8190f07b3c0a52c0b62c8b3f51de6ddf
        # save the attached .config to linux build tree
        make W=1 ARCH=um SUBARCH=x86_64

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 >>):

   kernel/time/hrtimer.c:120:21: warning: initialized field overwritten [-Woverride-init]
     120 |  [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
         |                     ^~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:120:21: note: (near initialization for 'hrtimer_clock_to_base_table[0]')
   kernel/time/hrtimer.c:121:22: warning: initialized field overwritten [-Woverride-init]
     121 |  [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
         |                      ^~~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:121:22: note: (near initialization for 'hrtimer_clock_to_base_table[1]')
   kernel/time/hrtimer.c:122:21: warning: initialized field overwritten [-Woverride-init]
     122 |  [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
         |                     ^~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:122:21: note: (near initialization for 'hrtimer_clock_to_base_table[7]')
   kernel/time/hrtimer.c:123:17: warning: initialized field overwritten [-Woverride-init]
     123 |  [CLOCK_TAI]  = HRTIMER_BASE_TAI,
         |                 ^~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:123:17: note: (near initialization for 'hrtimer_clock_to_base_table[11]')
   kernel/time/hrtimer.c: In function '__hrtimer_start_range_ns':
>> kernel/time/hrtimer.c:1232:44: warning: suggest parentheses around comparison in operand of '|' [-Wparentheses]
    1232 |  force_local &= base->cpu_base->next_timer == timer | in_callback;
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
   kernel/time/hrtimer.c: In function '__run_hrtimer':
   kernel/time/hrtimer.c:1652:7: warning: variable 'expires_in_hardirq' set but not used [-Wunused-but-set-variable]
    1652 |  bool expires_in_hardirq;
         |       ^~~~~~~~~~~~~~~~~~


vim +1232 kernel/time/hrtimer.c

  1211	
  1212	static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
  1213					    u64 delta_ns, const enum hrtimer_mode mode,
  1214					    struct hrtimer_clock_base *base)
  1215	{
  1216		struct hrtimer_clock_base *new_base;
  1217		bool in_callback, force_local, first;
  1218	
  1219		/*
  1220		 * If the timer is on the local cpu base and is the first expiring
  1221		 * timer then this might end up reprogramming the hardware twice
  1222		 * (on removal and on enqueue). To avoid that by prevent the
  1223		 * reprogram on removal, keep the timer local to the current CPU
  1224		 * and enforce reprogramming after it is queued no matter whether
  1225		 * it is the new first expiring timer again or not.
  1226		 *
  1227		 * Also avoid reprogramming if the timer callback is currently
  1228		 * running.
  1229		 */
  1230		in_callback = base->running == timer;
  1231		force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
> 1232		force_local &= base->cpu_base->next_timer == timer | in_callback;
  1233	
  1234		/*
  1235		 * Remove an active timer from the queue. In case it is not queued
  1236		 * on the current CPU, make sure that remove_hrtimer() updates the
  1237		 * remote data correctly.
  1238		 *
  1239		 * If it's on the current CPU and the first expiring timer, then
  1240		 * skip reprogramming, keep the timer local and enforce
  1241		 * reprogramming later if it was the first expiring timer.  This
  1242		 * avoids programming the underlying clock event twice (once at
  1243		 * removal and once after enqueue).
  1244		 */
  1245		remove_hrtimer(timer, base, true, force_local);
  1246	
  1247		if (mode & HRTIMER_MODE_REL)
  1248			tim = ktime_add_safe(tim, base->get_time());
  1249	
  1250		tim = hrtimer_update_lowres(timer, tim, mode);
  1251	
  1252		hrtimer_set_expires_range_ns(timer, tim, delta_ns);
  1253	
  1254		/* Switch the timer base, if necessary: */
  1255		if (!force_local) {
  1256			new_base = switch_hrtimer_base(timer, base,
  1257						       mode & HRTIMER_MODE_PINNED);
  1258		} else {
  1259			new_base = base;
  1260		}
  1261	
  1262		first = enqueue_hrtimer(timer, new_base, mode);
  1263		if (!force_local || in_callback)
  1264			return first;
  1265	
  1266		/*
  1267		 * Timer was forced to stay on the current CPU to avoid
  1268		 * reprogramming on removal and enqueue. Force reprogram the
  1269		 * hardware by evaluating the new first expiring timer.
  1270		 */
  1271		hrtimer_force_reprogram(new_base->cpu_base, 1);
  1272		return 0;
  1273	}
  1274	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org