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x86/smpboot: Remove wait for cpu_online()

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Now that the core code drops sparse_irq_lock after the idle thread
synchronized, it's pointless to wait for the AP to mark itself online.

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/20230512205256.316417181@linutronix.de
This commit is contained in:
Thomas Gleixner 2023-05-12 23:07:22 +02:00 committed by Peter Zijlstra
parent 22b612e2d5
commit e464640cf7
1 changed files with 2 additions and 24 deletions
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26
arch/x86/kernel/smpboot.c
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@ -275,7 +275,6 @@ static void notrace start_secondary(void *unused)
* half valid vector space.
*/
lock_vector_lock();
/* Sync point with do_wait_cpu_online() */
set_cpu_online(smp_processor_id(), true);
lapic_online();
unlock_vector_lock();
@ -1104,20 +1103,6 @@ static int wait_cpu_initialized(unsigned int cpu)
return 0;
}
/*
* Bringup step three: Wait for the target AP to reach set_cpu_online() in
* start_secondary().
*/
static void wait_cpu_online(unsigned int cpu)
{
/*
* Wait for the AP to mark itself online, so the core caller
* can drop sparse_irq_lock.
*/
while (!cpu_online(cpu))
schedule();
}
static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
{
int apicid = apic->cpu_present_to_apicid(cpu);
@ -1164,16 +1149,9 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
int ret;
ret = native_kick_ap(cpu, tidle);
if (ret)
goto out;
if (!ret)
ret = wait_cpu_initialized(cpu);
ret = wait_cpu_initialized(cpu);
if (ret)
goto out;
wait_cpu_online(cpu);
out:
/* Cleanup possible dangling ends... */
if (x86_platform.legacy.warm_reset)
smpboot_restore_warm_reset_vector();