[PATCH v2] powerpc/fadump: return error when fadump registration fails

[Michael Ellerman]

Mahesh Jagannath Salgaonkar <mahesh at linux.vnet.ibm.com> writes:

> On 05/27/2017 09:16 PM, Michal Suchanek wrote:
>>  - log an error message when registration fails and no error code listed
>>  in the switch is returned
>>  - translate the hv error code to posix error code and return it from
>>  fw_register
>>  - return the posix error code from fw_register to the process writing
>>  to sysfs
>>  - return EEXIST on re-registration
>>  - return success on deregistration when fadump is not registered
>>  - return ENODEV when no memory is reserved for fadump
>
> Why do we need this ?

Because that's how we do error handling.

> Userspace can always read back the fadump registration status from
> /sys/kernel/fadump_registered (after echo 1 to it) to find out
> whether fadump registration succeeded or not.

That's a terrible API.

If we followed that example, open() wouldn't return a value, you'd have
to do another syscall to check if it worked.

I'd appreciate if someone could test this and give me a Tested-by.

cheers