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Message-ID: <202308171624.uh1qEoWo-lkp@intel.com>
Date: Thu, 17 Aug 2023 16:28:56 +0800
From: kernel test robot <lkp@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
Frederic Weisbecker <frederic@...nel.org>
Subject: kernel/time/tick-broadcast.c:1026: warning: Function parameter or
member 'from_periodic' not described in 'tick_broadcast_setup_oneshot'
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 4853c74bd7ab7fdb83f319bd9ace8a08c031e9b6
commit: f9d36cf445ffff0b913ba187a3eff78028f9b1fb tick/broadcast: Make broadcast device replacement work correctly
date: 3 months ago
config: i386-randconfig-i013-20230817 (https://download.01.org/0day-ci/archive/20230817/202308171624.uh1qEoWo-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce: (https://download.01.org/0day-ci/archive/20230817/202308171624.uh1qEoWo-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308171624.uh1qEoWo-lkp@intel.com/
All warnings (new ones prefixed by >>):
kernel/time/tick-broadcast.c:1026: warning: Function parameter or member 'bc' not described in 'tick_broadcast_setup_oneshot'
>> kernel/time/tick-broadcast.c:1026: warning: Function parameter or member 'from_periodic' not described in 'tick_broadcast_setup_oneshot'
vim +1026 kernel/time/tick-broadcast.c
f73f64d5687192 Thomas Gleixner 2020-11-17 1020
79bf2bb335b85d Thomas Gleixner 2007-02-16 1021 /**
8dce39c231af55 Li Zefan 2007-11-05 1022 * tick_broadcast_setup_oneshot - setup the broadcast device
79bf2bb335b85d Thomas Gleixner 2007-02-16 1023 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1024 static void tick_broadcast_setup_oneshot(struct clock_event_device *bc,
f9d36cf445ffff Thomas Gleixner 2023-05-06 1025 bool from_periodic)
79bf2bb335b85d Thomas Gleixner 2007-02-16 @1026 {
07f4beb0b5bbfa Thomas Gleixner 2011-05-16 1027 int cpu = smp_processor_id();
f9d36cf445ffff Thomas Gleixner 2023-05-06 1028 ktime_t nexttick = 0;
07f4beb0b5bbfa Thomas Gleixner 2011-05-16 1029
c1a9eeb938b543 Thomas Gleixner 2016-12-15 1030 if (!bc)
c1a9eeb938b543 Thomas Gleixner 2016-12-15 1031 return;
c1a9eeb938b543 Thomas Gleixner 2016-12-15 1032
f9d36cf445ffff Thomas Gleixner 2023-05-06 1033 /*
f9d36cf445ffff Thomas Gleixner 2023-05-06 1034 * When the broadcast device was switched to oneshot by the first
f9d36cf445ffff Thomas Gleixner 2023-05-06 1035 * CPU handling the NOHZ change, the other CPUs will reach this
f9d36cf445ffff Thomas Gleixner 2023-05-06 1036 * code via hrtimer_run_queues() -> tick_check_oneshot_change()
f9d36cf445ffff Thomas Gleixner 2023-05-06 1037 * too. Set up the broadcast device only once!
f9d36cf445ffff Thomas Gleixner 2023-05-06 1038 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1039 if (bc->event_handler == tick_handle_oneshot_broadcast) {
f9d36cf445ffff Thomas Gleixner 2023-05-06 1040 /*
f9d36cf445ffff Thomas Gleixner 2023-05-06 1041 * The CPU which switched from periodic to oneshot mode
f9d36cf445ffff Thomas Gleixner 2023-05-06 1042 * set the broadcast oneshot bit for all other CPUs which
f9d36cf445ffff Thomas Gleixner 2023-05-06 1043 * are in the general (periodic) broadcast mask to ensure
f9d36cf445ffff Thomas Gleixner 2023-05-06 1044 * that CPUs which wait for the periodic broadcast are
f9d36cf445ffff Thomas Gleixner 2023-05-06 1045 * woken up.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1046 *
f9d36cf445ffff Thomas Gleixner 2023-05-06 1047 * Clear the bit for the local CPU as the set bit would
f9d36cf445ffff Thomas Gleixner 2023-05-06 1048 * prevent the first tick_broadcast_enter() after this CPU
f9d36cf445ffff Thomas Gleixner 2023-05-06 1049 * switched to oneshot state to program the broadcast
f9d36cf445ffff Thomas Gleixner 2023-05-06 1050 * device.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1051 *
f9d36cf445ffff Thomas Gleixner 2023-05-06 1052 * This code can also be reached via tick_broadcast_control(),
f9d36cf445ffff Thomas Gleixner 2023-05-06 1053 * but this cannot avoid the tick_broadcast_clear_oneshot()
f9d36cf445ffff Thomas Gleixner 2023-05-06 1054 * as that would break the periodic to oneshot transition of
f9d36cf445ffff Thomas Gleixner 2023-05-06 1055 * secondary CPUs. But that's harmless as the below only
f9d36cf445ffff Thomas Gleixner 2023-05-06 1056 * clears already cleared bits.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1057 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1058 tick_broadcast_clear_oneshot(cpu);
f9d36cf445ffff Thomas Gleixner 2023-05-06 1059 return;
f9d36cf445ffff Thomas Gleixner 2023-05-06 1060 }
f9d36cf445ffff Thomas Gleixner 2023-05-06 1061
7300711e8c6824 Thomas Gleixner 2008-09-06 1062
79bf2bb335b85d Thomas Gleixner 2007-02-16 1063 bc->event_handler = tick_handle_oneshot_broadcast;
f9d36cf445ffff Thomas Gleixner 2023-05-06 1064 bc->next_event = KTIME_MAX;
7300711e8c6824 Thomas Gleixner 2008-09-06 1065
7300711e8c6824 Thomas Gleixner 2008-09-06 1066 /*
f9d36cf445ffff Thomas Gleixner 2023-05-06 1067 * When the tick mode is switched from periodic to oneshot it must
f9d36cf445ffff Thomas Gleixner 2023-05-06 1068 * be ensured that CPUs which are waiting for periodic broadcast
f9d36cf445ffff Thomas Gleixner 2023-05-06 1069 * get their wake-up at the next tick. This is achieved by ORing
f9d36cf445ffff Thomas Gleixner 2023-05-06 1070 * tick_broadcast_mask into tick_broadcast_oneshot_mask.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1071 *
f9d36cf445ffff Thomas Gleixner 2023-05-06 1072 * For other callers, e.g. broadcast device replacement,
f9d36cf445ffff Thomas Gleixner 2023-05-06 1073 * tick_broadcast_oneshot_mask must not be touched as this would
f9d36cf445ffff Thomas Gleixner 2023-05-06 1074 * set bits for CPUs which are already NOHZ, but not idle. Their
f9d36cf445ffff Thomas Gleixner 2023-05-06 1075 * next tick_broadcast_enter() would observe the bit set and fail
f9d36cf445ffff Thomas Gleixner 2023-05-06 1076 * to update the expiry time and the broadcast event device.
7300711e8c6824 Thomas Gleixner 2008-09-06 1077 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1078 if (from_periodic) {
b352bc1cbc2913 Thomas Gleixner 2013-03-05 1079 cpumask_copy(tmpmask, tick_broadcast_mask);
f9d36cf445ffff Thomas Gleixner 2023-05-06 1080 /* Remove the local CPU as it is obviously not idle */
b352bc1cbc2913 Thomas Gleixner 2013-03-05 1081 cpumask_clear_cpu(cpu, tmpmask);
f9d36cf445ffff Thomas Gleixner 2023-05-06 1082 cpumask_or(tick_broadcast_oneshot_mask, tick_broadcast_oneshot_mask, tmpmask);
7300711e8c6824 Thomas Gleixner 2008-09-06 1083
f9d36cf445ffff Thomas Gleixner 2023-05-06 1084 /*
f9d36cf445ffff Thomas Gleixner 2023-05-06 1085 * Ensure that the oneshot broadcast handler will wake the
f9d36cf445ffff Thomas Gleixner 2023-05-06 1086 * CPUs which are still waiting for periodic broadcast.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1087 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1088 nexttick = tick_get_next_period();
f9d36cf445ffff Thomas Gleixner 2023-05-06 1089 tick_broadcast_init_next_event(tmpmask, nexttick);
f73f64d5687192 Thomas Gleixner 2020-11-17 1090
07f4beb0b5bbfa Thomas Gleixner 2011-05-16 1091 /*
f9d36cf445ffff Thomas Gleixner 2023-05-06 1092 * If the underlying broadcast clock event device is
f9d36cf445ffff Thomas Gleixner 2023-05-06 1093 * already in oneshot state, then there is nothing to do.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1094 * The device was already armed for the next tick
f9d36cf445ffff Thomas Gleixner 2023-05-06 1095 * in tick_handle_broadcast_periodic()
07f4beb0b5bbfa Thomas Gleixner 2011-05-16 1096 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1097 if (clockevent_state_oneshot(bc))
f9d36cf445ffff Thomas Gleixner 2023-05-06 1098 return;
79bf2bb335b85d Thomas Gleixner 2007-02-16 1099 }
f9d36cf445ffff Thomas Gleixner 2023-05-06 1100
f9d36cf445ffff Thomas Gleixner 2023-05-06 1101 /*
f9d36cf445ffff Thomas Gleixner 2023-05-06 1102 * When switching from periodic to oneshot mode arm the broadcast
f9d36cf445ffff Thomas Gleixner 2023-05-06 1103 * device for the next tick.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1104 *
f9d36cf445ffff Thomas Gleixner 2023-05-06 1105 * If the broadcast device has been replaced in oneshot mode and
f9d36cf445ffff Thomas Gleixner 2023-05-06 1106 * the oneshot broadcast mask is not empty, then arm it to expire
f9d36cf445ffff Thomas Gleixner 2023-05-06 1107 * immediately in order to reevaluate the next expiring timer.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1108 * @nexttick is 0 and therefore in the past which will cause the
f9d36cf445ffff Thomas Gleixner 2023-05-06 1109 * clockevent code to force an event.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1110 *
f9d36cf445ffff Thomas Gleixner 2023-05-06 1111 * For both cases the programming can be avoided when the oneshot
f9d36cf445ffff Thomas Gleixner 2023-05-06 1112 * broadcast mask is empty.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1113 *
f9d36cf445ffff Thomas Gleixner 2023-05-06 1114 * tick_broadcast_set_event() implicitly switches the broadcast
f9d36cf445ffff Thomas Gleixner 2023-05-06 1115 * device to oneshot state.
f9d36cf445ffff Thomas Gleixner 2023-05-06 1116 */
f9d36cf445ffff Thomas Gleixner 2023-05-06 1117 if (!cpumask_empty(tick_broadcast_oneshot_mask))
f9d36cf445ffff Thomas Gleixner 2023-05-06 1118 tick_broadcast_set_event(bc, cpu, nexttick);
9c17bcda991000 Thomas Gleixner 2008-09-03 1119 }
79bf2bb335b85d Thomas Gleixner 2007-02-16 1120
:::::: The code at line 1026 was first introduced by commit
:::::: 79bf2bb335b85db25d27421c798595a2fa2a0e82 [PATCH] tick-management: dyntick / highres functionality
:::::: TO: Thomas Gleixner <tglx@...utronix.de>
:::::: CC: Linus Torvalds <torvalds@...dy.linux-foundation.org>
--
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https://github.com/intel/lkp-tests/wiki
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