[tip: smp/core] ARM: smp: Switch to hotplug core state synchronization

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the smp/core branch of tip:

Commit-ID:     5490e769cdc7230cb93e804e656cce19d6c82253
Gitweb:        https://git.kernel.org/tip/5490e769cdc7230cb93e804e656cce19d6c82253
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Fri, 12 May 2023 23:07:32 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 15 May 2023 13:44:57 +02:00

ARM: smp: Switch to hotplug core state synchronization

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

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Tested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Tested-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>
Tested-by: Helge Deller <deller@xxxxxx> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> # Steam Deck
Link: https://lore.kernel.org/r/20230512205256.635326070@xxxxxxxxxxxxx
---
 arch/arm/Kconfig           |  1 +
 arch/arm/include/asm/smp.h |  2 +-
 arch/arm/kernel/smp.c      | 18 +++++++-----------
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0fb4b21..775ce86 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -124,6 +124,7 @@ config ARM
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_UID16
 	select HAVE_VIRT_CPU_ACCOUNTING_GEN
+	select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
 	select IRQ_FORCED_THREADING
 	select MODULES_USE_ELF_REL
 	select NEED_DMA_MAP_STATE
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
index 7c1c90d..8c05a7f 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -64,7 +64,7 @@ extern void secondary_startup_arm(void);
 
 extern int __cpu_disable(void);
 
-extern void __cpu_die(unsigned int cpu);
+static inline void __cpu_die(unsigned int cpu) { }
 
 extern void arch_send_call_function_single_ipi(int cpu);
 extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 87f8d0e..6756203 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -288,15 +288,11 @@ int __cpu_disable(void)
 }
 
 /*
- * 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)
 {
-	if (!cpu_wait_death(cpu, 5)) {
-		pr_err("CPU%u: cpu didn't die\n", cpu);
-		return;
-	}
 	pr_debug("CPU%u: shutdown\n", cpu);
 
 	clear_tasks_mm_cpumask(cpu);
@@ -336,11 +332,11 @@ void __noreturn arch_cpu_idle_dead(void)
 	flush_cache_louis();
 
 	/*
-	 * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
-	 * this returns, power and/or clocks can be removed at any point
-	 * from this CPU and its cache by platform_cpu_kill().
+	 * Tell cpuhp_bp_sync_dead() that this CPU is now safe to dispose
+	 * of. Once this returns, power and/or clocks can be removed at
+	 * any point from this CPU and its cache by platform_cpu_kill().
 	 */
-	(void)cpu_report_death();
+	cpuhp_ap_report_dead();
 
 	/*
 	 * Ensure that the cache lines associated with that completion are