[patch V2 21/38] ARM: smp: Switch to hotplug core state synchronization

From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, David Woodhouse <dwmw2@infradead.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Brian Gerst <brgerst@gmail.com>,
	Arjan van de Veen <arjan@linux.intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Paul McKenney <paulmck@kernel.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Sean Christopherson <seanjc@google.com>,
	Oleksandr Natalenko <oleksandr@natalenko.name>,
	Paul Menzel <pmenzel@molgen.mpg.de>,
	"Guilherme G. Piccoli" <gpiccoli@igalia.com>,
	Piotr Gorski <lucjan.lucjanov@gmail.com>,
	Usama Arif <usama.arif@bytedance.com>,
	Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	xen-devel@lists.xenproject.org,
	Russell King <linux@armlinux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>,
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Subject: [patch V2 21/38] ARM: smp: Switch to hotplug core state synchronization
Date: Thu,  4 May 2023 21:02:32 +0200 (CEST)	[thread overview]
Message-ID: <20230504185937.477649111@linutronix.de> (raw)
In-Reply-To: 20230504185733.126511787@linutronix.de

From: Thomas Gleixner <tglx@linutronix.de>

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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arm-kernel@lists.infradead.org

---
 arch/arm/Kconfig           |    1 +
 arch/arm/include/asm/smp.h |    2 +-
 arch/arm/kernel/smp.c      |   18 +++++++-----------
 3 files changed, 9 insertions(+), 12 deletions(-)
---

--- 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
--- 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);
--- 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


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