Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
Merge tag 'timers-urgent-2024-06-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Ingo Molnar:
"Fix boot-time warning in tick_setup_device()"
* tag 'timers-urgent-2024-06-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/nohz_full: Don't abuse smp_call_function_single() in tick_setup_device()
+14
-28
+14
-28
kernel/time/tick-common.c
+14
-28
kernel/time/tick-common.c
···
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}
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}
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#ifdef CONFIG_NO_HZ_FULL
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static void giveup_do_timer(void *info)
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{
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int cpu = *(unsigned int *)info;
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-
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WARN_ON(tick_do_timer_cpu != smp_processor_id());
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tick_do_timer_cpu = cpu;
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}
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static void tick_take_do_timer_from_boot(void)
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{
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int cpu = smp_processor_id();
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int from = tick_do_timer_boot_cpu;
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-
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if (from >= 0 && from != cpu)
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smp_call_function_single(from, giveup_do_timer, &cpu, 1);
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}
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#endif
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/*
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* Setup the tick device
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*/
···
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tick_next_period = ktime_get();
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#ifdef CONFIG_NO_HZ_FULL
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/*
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* The boot CPU may be nohz_full, in which case set
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* tick_do_timer_boot_cpu so the first housekeeping
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* secondary that comes up will take do_timer from
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* us.
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* The boot CPU may be nohz_full, in which case the
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* first housekeeping secondary will take do_timer()
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* from it.
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*/
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if (tick_nohz_full_cpu(cpu))
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tick_do_timer_boot_cpu = cpu;
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} else if (tick_do_timer_boot_cpu != -1 &&
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!tick_nohz_full_cpu(cpu)) {
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tick_take_do_timer_from_boot();
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} else if (tick_do_timer_boot_cpu != -1 && !tick_nohz_full_cpu(cpu)) {
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tick_do_timer_boot_cpu = -1;
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WARN_ON(READ_ONCE(tick_do_timer_cpu) != cpu);
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+
/*
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* The boot CPU will stay in periodic (NOHZ disabled)
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* mode until clocksource_done_booting() called after
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* smp_init() selects a high resolution clocksource and
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* timekeeping_notify() kicks the NOHZ stuff alive.
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*
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* So this WRITE_ONCE can only race with the READ_ONCE
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* check in tick_periodic() but this race is harmless.
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*/
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WRITE_ONCE(tick_do_timer_cpu, cpu);
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#endif
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}
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