[PATCHv3 0/2] cpu/hotplug: Keep cpu hotplug disabled until the rebooting cpu is stable

[PATCHv3 0/2] cpu/hotplug: Keep cpu hotplug disabled until the rebooting cpu is stable

[Pingfan Liu]

For the arches (arm/arm64/ia64/riscv), which relies on the cpu hot-removing
mechanism to implement "kexec -e", it is important to make sure that the
rebooting happens on a valid online cpu. And this logic should have been
guaranteed in migrate_to_reboot_cpu().

But the current code has either contradict (resolved by [2/2]) or
redundancy (resolved by [1/2]) about the logic.

V2 -> V3:
Taking in [2/2], which also has problem with the valid rebooting
cpu. (I had sent three patches for different arches. But maybe it is
better to collapse them into one and collect acks from different arches'
maintainers )

Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Donnefort <vincent.donnefort@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: Baokun Li <libaokun1@huawei.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: kexec@lists.infradead.org
Cc: Geert Uytterhoeven <geert@linux-m68k.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
To: linux-kernel@vger.kernel.org

Pingfan Liu (2):
  cpu/hotplug: Keep cpu hotplug disabled until the rebooting cpu is
    stable
  arm/arm64/ia64: kexec: fix the primary cpu passed to
    smp_shutdown_nonboot_cpus()

 arch/arm/kernel/reboot.c    |  2 +-
 arch/arm64/kernel/process.c |  2 +-
 arch/ia64/kernel/process.c  |  2 +-
 kernel/cpu.c                | 16 ++++++++++------
 kernel/kexec_core.c         | 10 ++++------
 5 files changed, 17 insertions(+), 15 deletions(-)

-- 
2.31.1


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[PATCHv3 2/2] arm/arm64/ia64: kexec: fix the primary cpu passed to smp_shutdown_nonboot_cpus()

[Pingfan Liu]

kernel_kexec()->migrate_to_reboot_cpu() has already pinned the reboot
thread on a valid online cpu, either reboot_cpu or the first online cpu.

So machine_shutdown() should pass smp_processor_id() of the pinned
thread as the primary cpu to smp_shutdown_nonboot_cpus().

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
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 Zijlstra <peterz@infradead.org>
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 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kernel/reboot.c b/arch/arm/kernel/reboot.c
index 3044fcb8d073..898405682e08 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(smp_processor_id());
 }
 
 /*
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 7fa97df55e3a..e5c130582cc6 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(smp_processor_id());
 }
 
 /*
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index d7a256bd9d6b..ae732e35e7da 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(smp_processor_id());
 
 #ifdef CONFIG_KEXEC
 	kexec_disable_iosapic();
-- 
2.31.1


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