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Message-ID: <202109200750.J1UMAIFx-lkp@intel.com>
Date: Mon, 20 Sep 2021 07:30:01 +0800
From: kernel test robot <lkp@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [tglx-devel:hrtimer 8/12] kernel/time/hrtimer.c:1232:44: warning:
suggest parentheses around comparison in operand of '|'
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@...el.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
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