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tick: Do not set device to detached state in tick_shutdown() 

tick_shutdown() sets the state of the clockevent device to detached
first and the invokes clockevents_exchange_device(), which in turn
invokes clockevents_switch_state().

But clockevents_switch_state() returns without invoking the device shutdown
callback as the device is already in detached state. As a consequence the
timer device is not shutdown when a CPU goes offline.

tick_shutdown() does this because it was originally invoked on a online CPU
and not on the outgoing CPU. It therefore could not access the clockevent
device of the already offlined CPU and just set the state.

Since commit 3b1596a21f tick_shutdown() is called on the outgoing CPU, so
the hardware device can be accessed.

Remove the state set before calling clockevents_exchange_device(), so that
the subsequent clockevents_switch_state() handles the state transition and
invokes the shutdown callback of the clockevent device.

[ tglx: Massaged change log ]

Fixes: 3b1596a21f ("clockevents: Shutdown and unregister current clockevents at CPUHP_AP_TICK_DYING")
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20250906064952.3749122-2-maobibo@loongson.cn
This commit is contained in:
Bibo Mao 2025-09-06 14:49:51 +08:00 committed by Thomas Gleixner
parent 3c3af563b3
commit fe2a449a45
3 changed files with 7 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/time/clockevents.c
View File

@ -633,7 +633,7 @@ void tick_offline_cpu(unsigned int cpu)
raw_spin_lock(&clockevents_lock);
tick_broadcast_offline(cpu);
tick_shutdown(cpu);
tick_shutdown();
/*
* Unregister the clock event devices which were

16
kernel/time/tick-common.c
View File

@ -411,24 +411,18 @@ int tick_cpu_dying(unsigned int dying_cpu)
}
/*
* Shutdown an event device on a given cpu:
* Shutdown an event device on the outgoing CPU:
*
* This is called on a life CPU, when a CPU is dead. So we cannot
* access the hardware device itself.
* We just set the mode and remove it from the lists.
* Called by the dying CPU during teardown, with clockevents_lock held
* and interrupts disabled.
*/
void tick_shutdown(unsigned int cpu)
void tick_shutdown(void)
{
struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
struct clock_event_device *dev = td->evtdev;
td->mode = TICKDEV_MODE_PERIODIC;
if (dev) {
/*
* Prevent that the clock events layer tries to call
* the set mode function!
*/
clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
clockevents_exchange_device(dev, NULL);
dev->event_handler = clockevents_handle_noop;
td->evtdev = NULL;

2
kernel/time/tick-internal.h
View File

@ -26,7 +26,7 @@ extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);
extern void tick_check_new_device(struct clock_event_device *dev);
extern void tick_offline_cpu(unsigned int cpu);
extern void tick_shutdown(unsigned int cpu);
extern void tick_shutdown(void);
extern void tick_suspend(void);
extern void tick_resume(void);
extern bool tick_check_replacement(struct clock_event_device *curdev,