[patch 22/37] arm64: smp: Switch to hotplug core state synchronization

Thomas Gleixner
2023-04-14T23:47:05Z

Switch to the CPU hotplug core state tracking and synchronization
mechanim. No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/smp.h | 2 +-
arch/arm64/kernel/smp.c | 14 +++++---------
3 files changed, 7 insertions(+), 10 deletions(-)

--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -216,6 +216,7 @@ config ARM64
select HAVE_KPROBES
select HAVE_KRETPROBES
select HAVE_GENERIC_VDSO
+ select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
select IRQ_DOMAIN
select IRQ_FORCED_THREADING
select KASAN_VMALLOC if KASAN
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -99,7 +99,7 @@ static inline void arch_send_wakeup_ipi_

extern int __cpu_disable(void);

-extern void __cpu_die(unsigned int cpu);
+static inline void __cpu_die(unsigned int cpu) { }
extern void cpu_die(void);
extern void cpu_die_early(void);

--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -333,17 +333,13 @@ static int op_cpu_kill(unsigned int cpu)
}

/*
- * called on the thread which is asking for a CPU to be shutdown -
- * waits until shutdown has completed, or it is timed out.
+ * Called on the thread which is asking for a CPU to be shutdown after the
+ * shutdown completed.
*/
-void __cpu_die(unsigned int cpu)
+void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
{
int err;

- if (!cpu_wait_death(cpu, 5)) {
- pr_crit("CPU%u: cpu didn't die\n", cpu);
- return;
- }
pr_debug("CPU%u: shutdown\n", cpu);

/*
@@ -370,8 +366,8 @@ void cpu_die(void)

local_daif_mask();

- /* Tell __cpu_die() that this CPU is now safe to dispose of */
- (void)cpu_report_death();
+ /* Tell cpuhp_bp_sync_dead() that this CPU is now safe to dispose of */
+ cpuhp_ap_report_dead();

/*
* Actually shutdown the CPU. This must never fail. The specific hotplug