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SubjectRe: [PATCH v3 3/6] crash hp: definitions and prototype changes
From
Baoquan,
Thanks for looking at this. Inline responses below.
eric

On 1/19/22 02:26, Baoquan He wrote:
> On 01/10/22 at 02:57pm, Eric DeVolder wrote:
>> This change adds members to struct kimage to facilitate crash
>> hotplug support.
>>
>> This change also defines crash hotplug events and associated
>> prototypes.
>>
>> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
>> ---
>> include/linux/kexec.h | 21 +++++++++++++++++++--
>> 1 file changed, 19 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index 0c994ae37729..068f853f1c65 100644
>> --- a/include/linux/kexec.h
>> +++ b/include/linux/kexec.h
>> @@ -221,8 +221,9 @@ struct crash_mem {
>> extern int crash_exclude_mem_range(struct crash_mem *mem,
>> unsigned long long mstart,
>> unsigned long long mend);
>> -extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
>> - void **addr, unsigned long *sz);
>> +extern int crash_prepare_elf64_headers(struct kimage *image,
>> + struct crash_mem *mem, int kernel_map,
>> + void **addr, unsigned long *sz);
>> #endif /* CONFIG_KEXEC_FILE */
>>
>> #ifdef CONFIG_KEXEC_ELF
>> @@ -299,6 +300,13 @@ struct kimage {
>>
>> /* Information for loading purgatory */
>> struct purgatory_info purgatory_info;
>> +
>> +#ifdef CONFIG_CRASH_HOTPLUG
>> + bool hotplug_event;
>> + int offlinecpu;
>> + bool elf_index_valid;
>> + int elf_index;
>
> Do we really need elf_index_valid? Can we initialize elf_index to , e.g '-1',
> then check if the value is valid?

These members become part of struct kimage, and when the kimage is allocated, it is automatically
zero'd. Wrt/ elf_index, 0 is a valid index, and so it needs to be qualified. I initially had used
-1, but that required code and was fragile as I had to find the right place to do that. Using the
boolean elf_index_valid, the problems with -1 vanish, and for free! I also found when examining the
code that reading 'elf_index_valid' was better than 'elf_index != -1', more clear.

Let me know what you think.
eric

>
>> +#endif
>> #endif
>>
>> #ifdef CONFIG_IMA_KEXEC
>> @@ -315,6 +323,15 @@ struct kimage {
>> unsigned long elf_load_addr;
>> };
>>
>> +#ifdef CONFIG_CRASH_HOTPLUG
>> +void arch_crash_hotplug_handler(struct kimage *image,
>> + unsigned int hp_action, unsigned long a, unsigned long b);
>> +#define KEXEC_CRASH_HP_REMOVE_CPU 0
>> +#define KEXEC_CRASH_HP_ADD_CPU 1
>> +#define KEXEC_CRASH_HP_REMOVE_MEMORY 2
>> +#define KEXEC_CRASH_HP_ADD_MEMORY 3
>> +#endif /* CONFIG_CRASH_HOTPLUG */
>> +
>> /* kexec interface functions */
>> extern void machine_kexec(struct kimage *image);
>> extern int machine_kexec_prepare(struct kimage *image);
>> --
>> 2.27.0
>>
>

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