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| author | Thomas Gleixner <tglx@linutronix.de> | 2023-05-12 23:07:27 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-05-15 13:44:55 +0200 |
| commit | 6f0621238b7e7680d5e26c00aa4cd473314d05b2 (patch) | |
| tree | 39796c2f8f1ef84b11038aac07f7e6b8dd4e75d8 /kernel/smpboot.c | |
| parent | ab24eb9abb9c60c45119370731735b79ed79f36c (diff) | |
| download | linux-6f0621238b7e7680d5e26c00aa4cd473314d05b2.tar.gz linux-6f0621238b7e7680d5e26c00aa4cd473314d05b2.tar.bz2 linux-6f0621238b7e7680d5e26c00aa4cd473314d05b2.zip | |
cpu/hotplug: Add CPU state tracking and synchronization
The CPU state tracking and synchronization mechanism in smpboot.c is
completely independent of the hotplug code and all logic around it is
implemented in architecture specific code.
Except for the state reporting of the AP there is absolutely nothing
architecture specific and the sychronization and decision functions can be
moved into the generic hotplug core code.
Provide an integrated variant and add the core synchronization and decision
points. This comes in two flavours:
1) DEAD state synchronization
Updated by the architecture code once the AP reaches the point where
it is ready to be torn down by the control CPU, e.g. by removing power
or clocks or tear down via the hypervisor.
The control CPU waits for this state to be reached with a timeout. If
the state is reached an architecture specific cleanup function is
invoked.
2) Full state synchronization
This extends #1 with AP alive synchronization. This is new
functionality, which allows to replace architecture specific wait
mechanims, e.g. cpumasks, completely.
It also prevents that an AP which is in a limbo state can be brought
up again. This can happen when an AP failed to report dead state
during a previous off-line operation.
The dead synchronization is what most architectures use. Only x86 makes a
bringup decision based on that state at the moment.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205256.476305035@linutronix.de
Diffstat (limited to 'kernel/smpboot.c')
| -rw-r--r-- | kernel/smpboot.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/smpboot.c b/kernel/smpboot.c index 2c7396da470c..3dcfd3f04ed0 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -326,6 +326,7 @@ void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread) } EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread); +#ifndef CONFIG_HOTPLUG_CORE_SYNC static DEFINE_PER_CPU(atomic_t, cpu_hotplug_state) = ATOMIC_INIT(CPU_POST_DEAD); /* @@ -488,3 +489,4 @@ bool cpu_report_death(void) } #endif /* #ifdef CONFIG_HOTPLUG_CPU */ +#endif /* !CONFIG_HOTPLUG_CORE_SYNC */ |