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

[Sourabh Jain <sourabhjain@linux.ibm.com>]

On 05/02/24 08:41, Baoquan He wrote:
> 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>

Thanks Baoquan He

- Sourabh

>
>> 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
>>