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

[Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>]

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@xxxxxxxxxx>

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


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