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parisc: Find a new timesync master if current CPU is removed

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When CPU hotplugging is enabled, the user may want to remove the
current CPU which is providing the timer ticks. If this happens
we need to find a new timesync master.

Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2022-03-27 15:03:53 +02:00
parent ca45ec3cb4
commit 1afde47d08
3 changed files with 10 additions and 1 deletions
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1
arch/parisc/include/asm/processor.h
View File

@ -95,6 +95,7 @@ struct cpuinfo_parisc {
extern struct system_cpuinfo_parisc boot_cpu_data;
DECLARE_PER_CPU(struct cpuinfo_parisc, cpu_data);
extern int time_keeper_id; /* CPU used for timekeeping */
#define CPU_HVERSION ((boot_cpu_data.hversion >> 4) & 0x0FFF)

6
arch/parisc/kernel/smp.c
View File

@ -465,6 +465,12 @@ int __cpu_disable(void)
*/
set_cpu_online(cpu, false);
/* Find a new timesync master */
if (cpu == time_keeper_id) {
time_keeper_id = cpumask_first(cpu_online_mask);
pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
}
disable_percpu_irq(IPI_IRQ);
irq_migrate_all_off_this_cpu();

4
arch/parisc/kernel/time.c
View File

@ -40,6 +40,8 @@
#include <linux/timex.h>
int time_keeper_id __read_mostly; /* CPU used for timekeeping. */
static unsigned long clocktick __ro_after_init; /* timer cycles per tick */
/*
@ -84,7 +86,7 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
cpuinfo->it_value = next_tick;
/* Go do system house keeping. */
if (cpu != 0)
if (IS_ENABLED(CONFIG_SMP) && (cpu != time_keeper_id))
ticks_elapsed = 0;
legacy_timer_tick(ticks_elapsed);