[PATCHv4 2/2] cpu/hotplug: Remove the input parameter primary_cpu of smp_shutdown_nonboot_cpus()

* [PATCHv4 2/2] cpu/hotplug: Remove the input parameter primary_cpu of smp_shutdown_nonboot_cpus()
       [not found] <20220512030619.13426-1-kernelfans@gmail.com>
@ 2022-05-12  3:06 ` Pingfan Liu
  2022-05-15 10:03   ` Catalin Marinas
  0 siblings, 1 reply; 2+ messages in thread
From: Pingfan Liu @ 2022-05-12  3:06 UTC (permalink / raw)
  To: linux-ia64, linux-arm-kernel
  Cc: Pingfan Liu, Thomas Gleixner, Geert Uytterhoeven, Peter Zijlstra,
	Kees Cook, Jens Axboe, Russell King, Guenter Roeck, Arnd Bergmann,
	Wolfram Sang, Lee Jones, Catalin Marinas, Will Deacon,
	Mark Rutland, Peter Collingbourne, Marc Zyngier, linux-kernel

For all call sites of smp_shutdown_nonboot_cpus(),

$git grep smp_shutdown_nonboot_cpus -- arch | grep -v \*
arch/arm/kernel/reboot.c:94:    smp_shutdown_nonboot_cpus(reboot_cpu);
arch/arm64/kernel/process.c:89: smp_shutdown_nonboot_cpus(reboot_cpu);
arch/ia64/kernel/process.c:578: smp_shutdown_nonboot_cpus(reboot_cpu);
arch/riscv/kernel/machine_kexec.c:135:  smp_shutdown_nonboot_cpus(smp_processor_id());

As it shows, the input parameter seems a little arbitrary.

Since kernel_kexec()->migrate_to_reboot_cpu() has already pinned the
rebooting thread on the selected CPU and the CPU hotplug keeps disabled
before smp_shutdown_nonboot_cpus(). Let smp_shutdown_nonboot_cpus()
deduce the rebooting CPU by smp_processor_id(), instead of passing the
parameter primary_cpu to it.

As a result, all call sites look consistent.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
To: linux-ia64@vger.kernel.org
Cc: Russell King <linux@armlinux.org.uk>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/arm/kernel/reboot.c          | 2 +-
 arch/arm64/kernel/process.c       | 2 +-
 arch/ia64/kernel/process.c        | 2 +-
 arch/riscv/kernel/machine_kexec.c | 2 +-
 include/linux/cpu.h               | 4 ++--
 kernel/cpu.c                      | 4 ++--
 6 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/arm/kernel/reboot.c b/arch/arm/kernel/reboot.c
index 3044fcb8d073..98c961f0b377 100644
--- a/arch/arm/kernel/reboot.c
+++ b/arch/arm/kernel/reboot.c
@@ -91,7 +91,7 @@ void soft_restart(unsigned long addr)
  */
 void machine_shutdown(void)
 {
-	smp_shutdown_nonboot_cpus(reboot_cpu);
+	smp_shutdown_nonboot_cpus();
 }
 
 /*
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 7fa97df55e3a..1f6498d44740 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -86,7 +86,7 @@ void arch_cpu_idle_dead(void)
  */
 void machine_shutdown(void)
 {
-	smp_shutdown_nonboot_cpus(reboot_cpu);
+	smp_shutdown_nonboot_cpus();
 }
 
 /*
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index d7a256bd9d6b..9af53ff43983 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -575,7 +575,7 @@ cpu_halt (void)
 
 void machine_shutdown(void)
 {
-	smp_shutdown_nonboot_cpus(reboot_cpu);
+	smp_shutdown_nonboot_cpus();
 
 #ifdef CONFIG_KEXEC
 	kexec_disable_iosapic();
diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c
index cbef0fc73afa..a30c545714cc 100644
--- a/arch/riscv/kernel/machine_kexec.c
+++ b/arch/riscv/kernel/machine_kexec.c
@@ -132,7 +132,7 @@ void machine_shutdown(void)
 	local_irq_disable();
 
 #if defined(CONFIG_HOTPLUG_CPU)
-	smp_shutdown_nonboot_cpus(smp_processor_id());
+	smp_shutdown_nonboot_cpus();
 #endif
 }
 
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 54dc2f9a2d56..0506ba3ac85e 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -127,7 +127,7 @@ extern void cpu_hotplug_enable(void);
 void clear_tasks_mm_cpumask(int cpu);
 int remove_cpu(unsigned int cpu);
 int cpu_device_down(struct device *dev);
-extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
+extern void smp_shutdown_nonboot_cpus(void);
 
 #else /* CONFIG_HOTPLUG_CPU */
 
@@ -140,7 +140,7 @@ static inline void lockdep_assert_cpus_held(void) { }
 static inline void cpu_hotplug_disable(void) { }
 static inline void cpu_hotplug_enable(void) { }
 static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
-static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
+static inline void smp_shutdown_nonboot_cpus(void) { }
 #endif	/* !CONFIG_HOTPLUG_CPU */
 
 #ifdef CONFIG_PM_SLEEP_SMP
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 4415370f0e91..66b8af6b8a3e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1228,7 +1228,7 @@ int remove_cpu(unsigned int cpu)
 }
 EXPORT_SYMBOL_GPL(remove_cpu);
 
-void smp_shutdown_nonboot_cpus(unsigned int primary_cpu)
+void smp_shutdown_nonboot_cpus(void)
 {
 	unsigned int cpu;
 	int error;
@@ -1244,7 +1244,7 @@ void smp_shutdown_nonboot_cpus(unsigned int primary_cpu)
 	__cpu_hotplug_enable();
 
 	for_each_online_cpu(cpu) {
-		if (cpu == primary_cpu)
+		if (cpu == smp_processor_id())
 			continue;
 
 		error = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
-- 
2.31.1


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