[PATCH] powerpc/mce: Add MCE notification chain

[Nicholas Piggin]

Ganesh Goudar's on March 30, 2020 5:12 pm:
> From: Santosh S <santosh at fossix.org>
> 
> Introduce notification chain which lets know about uncorrected memory
> errors(UE). This would help prospective users in pmem or nvdimm subsystem
> to track bad blocks for better handling of persistent memory allocations.
> 
> Signed-off-by: Santosh S <santosh at fossix.org>
> Signed-off-by: Ganesh Goudar <ganeshgr at linux.ibm.com>

Do you have any such users yet? It would be good to refer to an example 
user and give a brief description of what it does in its notifier.

> @@ -263,6 +277,7 @@ static void machine_process_ue_event(struct work_struct *work)
>  	while (__this_cpu_read(mce_ue_count) > 0) {
>  		index = __this_cpu_read(mce_ue_count) - 1;
>  		evt = this_cpu_ptr(&mce_ue_event_queue[index]);
> +		blocking_notifier_call_chain(&mce_notifier_list, 0, evt);

Can we really use a blocking notifier here? I'm not sure that we can.

Thanks,
Nick