Re: [PATCH v15 1/5] crash: forward memory_notify arg to arch crash hotplug handler

[Baoquan He <bhe@redhat.com>]

On 01/11/24 at 04:21pm, Sourabh Jain wrote:
> In the event of memory hotplug or online/offline events, the crash
> memory hotplug notifier `crash_memhp_notifier()` receives a
> `memory_notify` object but doesn't forward that object to the
> generic and architecture-specific crash hotplug handler.
> 
> The `memory_notify` object contains the starting PFN (Page Frame Number)
> and the number of pages in the hot-removed memory. This information is
> necessary for architectures like PowerPC to update/recreate the kdump
> image, specifically `elfcorehdr`.
> 
> So update the function signature of `crash_handle_hotplug_event()` and
> `arch_crash_handle_hotplug_event()` to accept the `memory_notify` object
> as an argument from crash memory hotplug notifier.
> 
> Since no such object is available in the case of CPU hotplug event, the
> crash CPU hotplug notifier `crash_cpuhp_online()` passes NULL to the
> crash hotplug handler.
> 
......
> ---
>  arch/x86/include/asm/kexec.h |  2 +-
>  arch/x86/kernel/crash.c      |  3 ++-
>  include/linux/kexec.h        |  2 +-
>  kernel/crash_core.c          | 14 +++++++-------
>  4 files changed, 11 insertions(+), 10 deletions(-)

LGTM,

Acked-by: Baoquan He <bhe@redhat.com>

> 
> diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
> index c9f6a6c5de3c..9bb6607e864e 100644
> --- a/arch/x86/include/asm/kexec.h
> +++ b/arch/x86/include/asm/kexec.h
> @@ -208,7 +208,7 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image);
>  extern void kdump_nmi_shootdown_cpus(void);
>  
>  #ifdef CONFIG_CRASH_HOTPLUG
> -void arch_crash_handle_hotplug_event(struct kimage *image);
> +void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
>  #define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
>  
>  #ifdef CONFIG_HOTPLUG_CPU
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index b6b044356f1b..44744e9c68ec 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -428,10 +428,11 @@ unsigned int arch_crash_get_elfcorehdr_size(void)
>  /**
>   * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
>   * @image: a pointer to kexec_crash_image
> + * @arg: struct memory_notify handler for memory hotplug case and NULL for CPU hotplug case.
>   *
>   * Prepare the new elfcorehdr and replace the existing elfcorehdr.
>   */
> -void arch_crash_handle_hotplug_event(struct kimage *image)
> +void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
>  {
>  	void *elfbuf = NULL, *old_elfcorehdr;
>  	unsigned long nr_mem_ranges;
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 400cb6c02176..802052d9c64b 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -483,7 +483,7 @@ static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) {
>  #endif
>  
>  #ifndef arch_crash_handle_hotplug_event
> -static inline void arch_crash_handle_hotplug_event(struct kimage *image) { }
> +static inline void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) { }
>  #endif
>  
>  int crash_check_update_elfcorehdr(void);
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index d48315667752..ab1c8e79759d 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -914,7 +914,7 @@ int crash_check_update_elfcorehdr(void)
>   * list of segments it checks (since the elfcorehdr changes and thus
>   * would require an update to purgatory itself to update the digest).
>   */
> -static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
> +static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu, void *arg)
>  {
>  	struct kimage *image;
>  
> @@ -976,7 +976,7 @@ static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
>  	image->hp_action = hp_action;
>  
>  	/* Now invoke arch-specific update handler */
> -	arch_crash_handle_hotplug_event(image);
> +	arch_crash_handle_hotplug_event(image, arg);
>  
>  	/* No longer handling a hotplug event */
>  	image->hp_action = KEXEC_CRASH_HP_NONE;
> @@ -992,17 +992,17 @@ static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
>  	crash_hotplug_unlock();
>  }
>  
> -static int crash_memhp_notifier(struct notifier_block *nb, unsigned long val, void *v)
> +static int crash_memhp_notifier(struct notifier_block *nb, unsigned long val, void *arg)
>  {
>  	switch (val) {
>  	case MEM_ONLINE:
>  		crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY,
> -			KEXEC_CRASH_HP_INVALID_CPU);
> +			KEXEC_CRASH_HP_INVALID_CPU, arg);
>  		break;
>  
>  	case MEM_OFFLINE:
>  		crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY,
> -			KEXEC_CRASH_HP_INVALID_CPU);
> +			KEXEC_CRASH_HP_INVALID_CPU, arg);
>  		break;
>  	}
>  	return NOTIFY_OK;
> @@ -1015,13 +1015,13 @@ static struct notifier_block crash_memhp_nb = {
>  
>  static int crash_cpuhp_online(unsigned int cpu)
>  {
> -	crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu);
> +	crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu, NULL);
>  	return 0;
>  }
>  
>  static int crash_cpuhp_offline(unsigned int cpu)
>  {
> -	crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu);
> +	crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu, NULL);
>  	return 0;
>  }
>  
> -- 
> 2.41.0
>