Subject: [PATCH v29 4/9] arm64: kdump: implement machine_crash_shutdown()

From: [email-masked] (Will Deacon)
Date: Tue, 10 Jan 2017 11:32:48 +0000

On Wed, Dec 28, 2016 at 01:36:01PM +0900, AKASHI Takahiro wrote:
> Primary kernel calls machine_crash_shutdown() to shut down non-boot cpus
> and save registers' status in per-cpu ELF notes before starting crash
> dump kernel. See kernel_kexec().
> Even if not all secondary cpus have shut down, we do kdump anyway.
> 
> As we don't have to make non-boot(crashed) cpus offline (to preserve
> correct status of cpus at crash dump) before shutting down, this patch
> also adds a variant of smp_send_stop().
> 
> Signed-off-by: AKASHI Takahiro <[email-masked]>
> Reviewed-by: James Morse <[email-masked]>
> Acked-by: Catalin Marinas <[email-masked]>
> ---
>  arch/arm64/include/asm/hardirq.h  |  2 +-
>  arch/arm64/include/asm/kexec.h    | 42 +++++++++++++++++++++++++-
>  arch/arm64/include/asm/smp.h      |  2 ++
>  arch/arm64/kernel/machine_kexec.c | 56 ++++++++++++++++++++++++++++++++--
>  arch/arm64/kernel/smp.c           | 63 +++++++++++++++++++++++++++++++++++++++
>  5 files changed, 160 insertions(+), 5 deletions(-)

[...]

> diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
> index d050d720a1b4..cea009f2657d 100644
> --- a/arch/arm64/include/asm/smp.h
> +++ b/arch/arm64/include/asm/smp.h
> @@ -148,6 +148,8 @@ static inline void cpu_panic_kernel(void)
>   */
>  bool cpus_are_stuck_in_kernel(void);
>  
> +extern void smp_send_crash_stop(void);
> +
>  #endif /* ifndef __ASSEMBLY__ */
>  
>  #endif /* ifndef __ASM_SMP_H */
> diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> index bc96c8a7fc79..c60346d33bb1 100644
> --- a/arch/arm64/kernel/machine_kexec.c
> +++ b/arch/arm64/kernel/machine_kexec.c
> @@ -9,6 +9,9 @@
>   * published by the Free Software Foundation.
>   */
>  
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
>  #include <linux/kexec.h>
>  #include <linux/smp.h>
>  
> @@ -22,6 +25,7 @@
>  extern const unsigned char arm64_relocate_new_kernel[];
>  extern const unsigned long arm64_relocate_new_kernel_size;
>  
> +static bool in_crash_kexec;

Do you actually need this bool? Why not call kexec_crash_loaded() instead?

Will