[PATCH v4 0/3] Give chance to build under !CONFIG_SMP for LoongArch

[PATCH v4 0/3] Give chance to build under !CONFIG_SMP for LoongArch

[Tiezhu Yang]

The changes of irqchip have been merged into the irq/core branch of tip.

https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=42a7d887664b
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=a64003da0ef8

This version is only related with arch/loongarch and based on 6.9-rc4,
drop the patch "LoongArch: Move CONFIG_HAVE_SETUP_PER_CPU_AREA related
code to smp.c" to use the generic setup_per_cpu_areas() if CONFIG_NUMA
is not set.

The first 2 patches with detailed commit message are preparations for
patch #3.

Tested with the following configs:
(1) CONFIG_NUMA=n, CONFIG_SMP=n
(2) CONFIG_NUMA=n, CONFIG_SMP=y
(3) CONFIG_NUMA=y, CONFIG_SMP=n (not allowed due to NUMA select SMP)
(4) CONFIG_NUMA=y, CONFIG_SMP=y

Tiezhu Yang (3):
  LoongArch: Modify acpi_parse_processor() for non-SMP
  LoongArch: Modify ACPI S3 state function for non-SMP
  LoongArch: Give chance to build under !CONFIG_SMP

 arch/loongarch/Kconfig                | 2 +-
 arch/loongarch/include/asm/acpi.h     | 1 +
 arch/loongarch/include/asm/smp.h      | 5 +++++
 arch/loongarch/kernel/acpi.c          | 9 ++++++++-
 arch/loongarch/kernel/irq.c           | 2 ++
 arch/loongarch/kernel/machine_kexec.c | 2 +-
 arch/loongarch/power/suspend.c        | 4 +++-
 7 files changed, 21 insertions(+), 4 deletions(-)

-- 
2.42.0

[PATCH v4 1/3] LoongArch: Modify acpi_parse_processor() for non-SMP

[Tiezhu Yang]

When CONFIG_SMP is disabled, mapping won't be created for all cpus.
CPUs more than num_possible_cpus will be ignored. This is preparation
for later patch.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/loongarch/kernel/acpi.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c
index 5cf59c617126..ccfa90faf0ea 100644
--- a/arch/loongarch/kernel/acpi.c
+++ b/arch/loongarch/kernel/acpi.c
@@ -98,8 +98,15 @@ acpi_parse_processor(union acpi_subtable_headers *header, const unsigned long en
 		return -EINVAL;
 
 	acpi_table_print_madt_entry(&header->common);
+
+	/*
+	 * When CONFIG_SMP is disabled, mapping won't be created for all cpus.
+	 * CPUs more than num_possible_cpus will be ignored.
+	 */
+	if (processor->core_id >= 0 && processor->core_id < num_possible_cpus())
+		acpi_core_pic[processor->core_id] = *processor;
+
 #ifdef CONFIG_SMP
-	acpi_core_pic[processor->core_id] = *processor;
 	set_processor_mask(processor->core_id, processor->flags);
 #endif
 
-- 
2.42.0

[PATCH v4 2/3] LoongArch: Modify ACPI S3 state function for non-SMP

[Tiezhu Yang]

Currently, per_cpu_offset(x) is defined as __per_cpu_offset[x])
only under CONFIG_SMP in include/asm-generic/percpu.h, that is
to say, the implementation of loongarch_common_resume() which
calls per_cpu_offset(0) is not suitable for the case of non-SMP,
so do not write per_cpu_offset(0) to PERCPU_BASE_KS when resume,
just save the value of PERCPU_BASE_KS when suspend and restore
it when resume to avoid compiling error for non-SMP and make it
work well for both SMP and non-SMP.

This is preparation for later patch. Tested with the command
"rtcwake -d rtc1 -s 20 -m mem", dmesg shows that "PM: suspend
entry (deep)" and "PM: suspend exit".

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/loongarch/power/suspend.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/power/suspend.c b/arch/loongarch/power/suspend.c
index 166d9e06a64b..8571818b93dc 100644
--- a/arch/loongarch/power/suspend.c
+++ b/arch/loongarch/power/suspend.c
@@ -24,6 +24,7 @@ struct saved_registers {
 	u64 kpgd;
 	u32 pwctl0;
 	u32 pwctl1;
+	u64 pcpu_base;
 };
 static struct saved_registers saved_regs;
 
@@ -36,6 +37,7 @@ void loongarch_common_suspend(void)
 	saved_regs.pwctl1 = csr_read32(LOONGARCH_CSR_PWCTL1);
 	saved_regs.ecfg = csr_read32(LOONGARCH_CSR_ECFG);
 	saved_regs.euen = csr_read32(LOONGARCH_CSR_EUEN);
+	saved_regs.pcpu_base = csr_read64(PERCPU_BASE_KS);
 
 	loongarch_suspend_addr = loongson_sysconf.suspend_addr;
 }
@@ -44,7 +46,7 @@ void loongarch_common_resume(void)
 {
 	sync_counter();
 	local_flush_tlb_all();
-	csr_write64(per_cpu_offset(0), PERCPU_BASE_KS);
+	csr_write64(saved_regs.pcpu_base, PERCPU_BASE_KS);
 	csr_write64(eentry, LOONGARCH_CSR_EENTRY);
 	csr_write64(eentry, LOONGARCH_CSR_MERRENTRY);
 	csr_write64(tlbrentry, LOONGARCH_CSR_TLBRENTRY);
-- 
2.42.0

[PATCH v4 3/3] LoongArch: Give chance to build under !CONFIG_SMP

[Tiezhu Yang]

In the current code, SMP is selected in Kconfig for LoongArch, the users
can not unset it, this is reasonable for a multiprocessor machine. But as
the help info of config SMP said, if you have a system with only one CPU,
say N. On a uniprocessor machine, the kernel will run faster if you say N
here.

The Loongson-2K0500 is a single-core CPU for applications like industrial
control, printing terminals, and BMC (Baseboard Management Controller),
there are many development boards, products and solutions on the market,
so it is better and necessary to give a chance to build under !CONFIG_SMP
for a uniprocessor machine.

First of all, do not select SMP for config LOONGARCH in Kconfig to make it
possible to unset CONFIG_SMP. Then, do some changes to fix the warnings and
errors if CONFIG_SMP is not set.

(1) Define get_ipi_irq() only if CONFIG_SMP is set to fix the warning:
arch/loongarch/kernel/irq.c:90:19: warning: 'get_ipi_irq' defined but not used [-Wunused-function]

(2) Add "#ifdef CONFIG_SMP" in asm/smp.h to fix the warning:
./arch/loongarch/include/asm/smp.h:49:9: warning: "raw_smp_processor_id" redefined
   49 | #define raw_smp_processor_id raw_smp_processor_id
      |         ^~~~~~~~~~~~~~~~~~~~
./include/linux/smp.h:198:9: note: this is the location of the previous definition
  198 | #define raw_smp_processor_id()                  0

(3) Define machine_shutdown() as empty under !CONFIG_SMP to fix the error:
arch/loongarch/kernel/machine_kexec.c: In function 'machine_shutdown':
arch/loongarch/kernel/machine_kexec.c:233:25: error: implicit declaration of function 'cpu_device_up'; did you mean 'put_device'? [-Wimplicit-function-declaration]

(4) Make config SCHED_SMT depends on SMP to fix many errors such as:
kernel/sched/core.c: In function 'sched_core_find':
kernel/sched/core.c:310:43: error: 'struct rq' has no member named 'cpu'

(5) Define cpu_logical_map(cpu) as read_csr_cpuid() under !CONFIG_SMP
in asm/smp.h and then include asm/smp.h in asm/acpi.h (because acpi.h
is included in linux/irq.h indirectly) to fix many build errors under
drivers/irqchip such as:
drivers/irqchip/irq-loongson-eiointc.c: In function 'cpu_to_eio_node':
drivers/irqchip/irq-loongson-eiointc.c:59:16: error: implicit declaration of function 'cpu_logical_map' [-Wimplicit-function-declaration]

When running the UnixBench tests with "-c 1" single-streamed pass,
the improvement in performance is about 9 percent with this patch.

By the way, it is helpful to debug and analysis the kernel issue
of multi-core system under !CONFIG_SMP.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/loongarch/Kconfig                | 2 +-
 arch/loongarch/include/asm/acpi.h     | 1 +
 arch/loongarch/include/asm/smp.h      | 5 +++++
 arch/loongarch/kernel/irq.c           | 2 ++
 arch/loongarch/kernel/machine_kexec.c | 2 +-
 5 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index a5f300ec6f28..8d892de0b7a8 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -174,7 +174,6 @@ config LOONGARCH
 	select PCI_QUIRKS
 	select PERF_USE_VMALLOC
 	select RTC_LIB
-	select SMP
 	select SPARSE_IRQ
 	select SYSCTL_ARCH_UNALIGN_ALLOW
 	select SYSCTL_ARCH_UNALIGN_NO_WARN
@@ -420,6 +419,7 @@ config EFI_STUB
 
 config SCHED_SMT
 	bool "SMT scheduler support"
+	depends on SMP
 	default y
 	help
 	  Improves scheduler's performance when there are multiple
diff --git a/arch/loongarch/include/asm/acpi.h b/arch/loongarch/include/asm/acpi.h
index 49e29b29996f..313f66f7913a 100644
--- a/arch/loongarch/include/asm/acpi.h
+++ b/arch/loongarch/include/asm/acpi.h
@@ -8,6 +8,7 @@
 #ifndef _ASM_LOONGARCH_ACPI_H
 #define _ASM_LOONGARCH_ACPI_H
 
+#include <asm/smp.h>
 #include <asm/suspend.h>
 
 #ifdef CONFIG_ACPI
diff --git a/arch/loongarch/include/asm/smp.h b/arch/loongarch/include/asm/smp.h
index f81e5f01d619..1ec11b57e60c 100644
--- a/arch/loongarch/include/asm/smp.h
+++ b/arch/loongarch/include/asm/smp.h
@@ -6,6 +6,7 @@
 #ifndef __ASM_SMP_H
 #define __ASM_SMP_H
 
+#ifdef CONFIG_SMP
 #include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/linkage.h>
@@ -101,4 +102,8 @@ static inline void __cpu_die(unsigned int cpu)
 }
 #endif
 
+#else /* !CONFIG_SMP */
+#define cpu_logical_map(cpu)	read_csr_cpuid()
+#endif /* CONFIG_SMP */
+
 #endif /* __ASM_SMP_H */
diff --git a/arch/loongarch/kernel/irq.c b/arch/loongarch/kernel/irq.c
index 883e5066ae44..e791fa275ec5 100644
--- a/arch/loongarch/kernel/irq.c
+++ b/arch/loongarch/kernel/irq.c
@@ -87,6 +87,7 @@ static void __init init_vec_parent_group(void)
 	acpi_table_parse(ACPI_SIG_MCFG, early_pci_mcfg_parse);
 }
 
+#ifdef CONFIG_SMP
 static int __init get_ipi_irq(void)
 {
 	struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
@@ -96,6 +97,7 @@ static int __init get_ipi_irq(void)
 
 	return -EINVAL;
 }
+#endif
 
 void __init init_IRQ(void)
 {
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
index 2dcb9e003657..8ae641dc53bb 100644
--- a/arch/loongarch/kernel/machine_kexec.c
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -225,6 +225,7 @@ void crash_smp_send_stop(void)
 
 void machine_shutdown(void)
 {
+#ifdef CONFIG_SMP
 	int cpu;
 
 	/* All CPUs go to reboot_code_buffer */
@@ -232,7 +233,6 @@ void machine_shutdown(void)
 		if (!cpu_online(cpu))
 			cpu_device_up(get_cpu_device(cpu));
 
-#ifdef CONFIG_SMP
 	smp_call_function(kexec_shutdown_secondary, NULL, 0);
 #endif
 }
-- 
2.42.0

Re: [PATCH v4 1/3] LoongArch: Modify acpi_parse_processor() for non-SMP

[Huacai Chen]

Hi, Tiezhu,

On Wed, Apr 17, 2024 at 6:00 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> When CONFIG_SMP is disabled, mapping won't be created for all cpus.
> CPUs more than num_possible_cpus will be ignored. This is preparation
> for later patch.
This patch makes no sense, don't "fix" anything unless it is broken.

Huacai

>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  arch/loongarch/kernel/acpi.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c
> index 5cf59c617126..ccfa90faf0ea 100644
> --- a/arch/loongarch/kernel/acpi.c
> +++ b/arch/loongarch/kernel/acpi.c
> @@ -98,8 +98,15 @@ acpi_parse_processor(union acpi_subtable_headers *header, const unsigned long en
>                 return -EINVAL;
>
>         acpi_table_print_madt_entry(&header->common);
> +
> +       /*
> +        * When CONFIG_SMP is disabled, mapping won't be created for all cpus.
> +        * CPUs more than num_possible_cpus will be ignored.
> +        */
> +       if (processor->core_id >= 0 && processor->core_id < num_possible_cpus())
> +               acpi_core_pic[processor->core_id] = *processor;
> +
>  #ifdef CONFIG_SMP
> -       acpi_core_pic[processor->core_id] = *processor;
>         set_processor_mask(processor->core_id, processor->flags);
>  #endif
>
> --
> 2.42.0
>
>

Re: [PATCH v4 2/3] LoongArch: Modify ACPI S3 state function for non-SMP

[Huacai Chen]

Hi, Tiezhu,

On Wed, Apr 17, 2024 at 6:00 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> Currently, per_cpu_offset(x) is defined as __per_cpu_offset[x])
> only under CONFIG_SMP in include/asm-generic/percpu.h, that is
> to say, the implementation of loongarch_common_resume() which
> calls per_cpu_offset(0) is not suitable for the case of non-SMP,
> so do not write per_cpu_offset(0) to PERCPU_BASE_KS when resume,
> just save the value of PERCPU_BASE_KS when suspend and restore
> it when resume to avoid compiling error for non-SMP and make it
> work well for both SMP and non-SMP.
>
> This is preparation for later patch. Tested with the command
> "rtcwake -d rtc1 -s 20 -m mem", dmesg shows that "PM: suspend
> entry (deep)" and "PM: suspend exit".
This patch can be squashed to the 3rd patch.

Huacai
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  arch/loongarch/power/suspend.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/power/suspend.c b/arch/loongarch/power/suspend.c
> index 166d9e06a64b..8571818b93dc 100644
> --- a/arch/loongarch/power/suspend.c
> +++ b/arch/loongarch/power/suspend.c
> @@ -24,6 +24,7 @@ struct saved_registers {
>         u64 kpgd;
>         u32 pwctl0;
>         u32 pwctl1;
> +       u64 pcpu_base;
>  };
>  static struct saved_registers saved_regs;
>
> @@ -36,6 +37,7 @@ void loongarch_common_suspend(void)
>         saved_regs.pwctl1 = csr_read32(LOONGARCH_CSR_PWCTL1);
>         saved_regs.ecfg = csr_read32(LOONGARCH_CSR_ECFG);
>         saved_regs.euen = csr_read32(LOONGARCH_CSR_EUEN);
> +       saved_regs.pcpu_base = csr_read64(PERCPU_BASE_KS);
>
>         loongarch_suspend_addr = loongson_sysconf.suspend_addr;
>  }
> @@ -44,7 +46,7 @@ void loongarch_common_resume(void)
>  {
>         sync_counter();
>         local_flush_tlb_all();
> -       csr_write64(per_cpu_offset(0), PERCPU_BASE_KS);
> +       csr_write64(saved_regs.pcpu_base, PERCPU_BASE_KS);
>         csr_write64(eentry, LOONGARCH_CSR_EENTRY);
>         csr_write64(eentry, LOONGARCH_CSR_MERRENTRY);
>         csr_write64(tlbrentry, LOONGARCH_CSR_TLBRENTRY);
> --
> 2.42.0
>

Re: [PATCH v4 3/3] LoongArch: Give chance to build under !CONFIG_SMP

[Huacai Chen]

Hi, Tiezhu,

On Wed, Apr 17, 2024 at 6:00 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> In the current code, SMP is selected in Kconfig for LoongArch, the users
> can not unset it, this is reasonable for a multiprocessor machine. But as
> the help info of config SMP said, if you have a system with only one CPU,
> say N. On a uniprocessor machine, the kernel will run faster if you say N
> here.
>
> The Loongson-2K0500 is a single-core CPU for applications like industrial
> control, printing terminals, and BMC (Baseboard Management Controller),
> there are many development boards, products and solutions on the market,
> so it is better and necessary to give a chance to build under !CONFIG_SMP
> for a uniprocessor machine.
>
> First of all, do not select SMP for config LOONGARCH in Kconfig to make it
> possible to unset CONFIG_SMP. Then, do some changes to fix the warnings and
> errors if CONFIG_SMP is not set.
>
> (1) Define get_ipi_irq() only if CONFIG_SMP is set to fix the warning:
> arch/loongarch/kernel/irq.c:90:19: warning: 'get_ipi_irq' defined but not used [-Wunused-function]
>
> (2) Add "#ifdef CONFIG_SMP" in asm/smp.h to fix the warning:
> ./arch/loongarch/include/asm/smp.h:49:9: warning: "raw_smp_processor_id" redefined
>    49 | #define raw_smp_processor_id raw_smp_processor_id
>       |         ^~~~~~~~~~~~~~~~~~~~
> ./include/linux/smp.h:198:9: note: this is the location of the previous definition
>   198 | #define raw_smp_processor_id()                  0
>
> (3) Define machine_shutdown() as empty under !CONFIG_SMP to fix the error:
> arch/loongarch/kernel/machine_kexec.c: In function 'machine_shutdown':
> arch/loongarch/kernel/machine_kexec.c:233:25: error: implicit declaration of function 'cpu_device_up'; did you mean 'put_device'? [-Wimplicit-function-declaration]
>
> (4) Make config SCHED_SMT depends on SMP to fix many errors such as:
> kernel/sched/core.c: In function 'sched_core_find':
> kernel/sched/core.c:310:43: error: 'struct rq' has no member named 'cpu'
>
> (5) Define cpu_logical_map(cpu) as read_csr_cpuid() under !CONFIG_SMP
> in asm/smp.h and then include asm/smp.h in asm/acpi.h (because acpi.h
> is included in linux/irq.h indirectly) to fix many build errors under
> drivers/irqchip such as:
> drivers/irqchip/irq-loongson-eiointc.c: In function 'cpu_to_eio_node':
> drivers/irqchip/irq-loongson-eiointc.c:59:16: error: implicit declaration of function 'cpu_logical_map' [-Wimplicit-function-declaration]
>
> When running the UnixBench tests with "-c 1" single-streamed pass,
> the improvement in performance is about 9 percent with this patch.
>
> By the way, it is helpful to debug and analysis the kernel issue
> of multi-core system under !CONFIG_SMP.
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  arch/loongarch/Kconfig                | 2 +-
>  arch/loongarch/include/asm/acpi.h     | 1 +
>  arch/loongarch/include/asm/smp.h      | 5 +++++
>  arch/loongarch/kernel/irq.c           | 2 ++
>  arch/loongarch/kernel/machine_kexec.c | 2 +-
>  5 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index a5f300ec6f28..8d892de0b7a8 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -174,7 +174,6 @@ config LOONGARCH
>         select PCI_QUIRKS
>         select PERF_USE_VMALLOC
>         select RTC_LIB
> -       select SMP
>         select SPARSE_IRQ
>         select SYSCTL_ARCH_UNALIGN_ALLOW
>         select SYSCTL_ARCH_UNALIGN_NO_WARN
> @@ -420,6 +419,7 @@ config EFI_STUB
>
>  config SCHED_SMT
>         bool "SMT scheduler support"
> +       depends on SMP
>         default y
>         help
>           Improves scheduler's performance when there are multiple
> diff --git a/arch/loongarch/include/asm/acpi.h b/arch/loongarch/include/asm/acpi.h
> index 49e29b29996f..313f66f7913a 100644
> --- a/arch/loongarch/include/asm/acpi.h
> +++ b/arch/loongarch/include/asm/acpi.h
> @@ -8,6 +8,7 @@
>  #ifndef _ASM_LOONGARCH_ACPI_H
>  #define _ASM_LOONGARCH_ACPI_H
>
> +#include <asm/smp.h>
>  #include <asm/suspend.h>
>
>  #ifdef CONFIG_ACPI
> diff --git a/arch/loongarch/include/asm/smp.h b/arch/loongarch/include/asm/smp.h
> index f81e5f01d619..1ec11b57e60c 100644
> --- a/arch/loongarch/include/asm/smp.h
> +++ b/arch/loongarch/include/asm/smp.h
> @@ -6,6 +6,7 @@
>  #ifndef __ASM_SMP_H
>  #define __ASM_SMP_H
>
> +#ifdef CONFIG_SMP
>  #include <linux/atomic.h>
>  #include <linux/bitops.h>
>  #include <linux/linkage.h>
> @@ -101,4 +102,8 @@ static inline void __cpu_die(unsigned int cpu)
>  }
>  #endif
>
> +#else /* !CONFIG_SMP */
> +#define cpu_logical_map(cpu)   read_csr_cpuid()
> +#endif /* CONFIG_SMP */
Non-SMP kernel is not supposed to run on SMP hardware, just define it
to 0 to keep it as simple as possible.

Huacai

> +
>  #endif /* __ASM_SMP_H */
> diff --git a/arch/loongarch/kernel/irq.c b/arch/loongarch/kernel/irq.c
> index 883e5066ae44..e791fa275ec5 100644
> --- a/arch/loongarch/kernel/irq.c
> +++ b/arch/loongarch/kernel/irq.c
> @@ -87,6 +87,7 @@ static void __init init_vec_parent_group(void)
>         acpi_table_parse(ACPI_SIG_MCFG, early_pci_mcfg_parse);
>  }
>
> +#ifdef CONFIG_SMP
>  static int __init get_ipi_irq(void)
>  {
>         struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
> @@ -96,6 +97,7 @@ static int __init get_ipi_irq(void)
>
>         return -EINVAL;
>  }
> +#endif
>
>  void __init init_IRQ(void)
>  {
> diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
> index 2dcb9e003657..8ae641dc53bb 100644
> --- a/arch/loongarch/kernel/machine_kexec.c
> +++ b/arch/loongarch/kernel/machine_kexec.c
> @@ -225,6 +225,7 @@ void crash_smp_send_stop(void)
>
>  void machine_shutdown(void)
>  {
> +#ifdef CONFIG_SMP
>         int cpu;
>
>         /* All CPUs go to reboot_code_buffer */
> @@ -232,7 +233,6 @@ void machine_shutdown(void)
>                 if (!cpu_online(cpu))
>                         cpu_device_up(get_cpu_device(cpu));
>
> -#ifdef CONFIG_SMP
>         smp_call_function(kexec_shutdown_secondary, NULL, 0);
>  #endif
>  }
> --
> 2.42.0
>
>