Re: [PATCH v2 1/7] s390/kdump: implement is_kdump_kernel()

Alexander Egorenkov
2024-10-21T12:46:23Z

Hi David,

David Hildenbrand <david@redhat.com> writes:

> Makes sense, so it boils down to either
>
> bool is_kdump_kernel(void)
> {
> return oldmem_data.start;
> }
>
> Which means is_kdump_kernel() can be "false" even though /proc/vmcore is
> available or
>
> bool is_kdump_kernel(void)
> {
> return dump_available();
> }
>
> Which means is_kdump_kernel() can never be "false" if /proc/vmcore is
> available. There is the chance of is_kdump_kernel() being "true" if
> "elfcorehdr_alloc()" fails with -ENODEV.

Do you consider is_kdump_kernel() returning "true" in case of zfcpdump or
nvme/eckd+ldipl dump (also called NGDump) okay ? Because
dump_available() would return "true" in such cases too.
If yes then please explain why, i might have missed a previous
explanation from you.

I'm afraid everyone will make wrong assumptions while reading the name
of is_kdump_kernel() and assuming that it only applies to kdump or
kdump-alike dumps (like stand-alone kdump), and, therefore, introduce
bugs because the name of the function conveys the wrong idea to code
readers. I consider dump_available() as a superset of is_kdump_kernel()
and, therefore, to me they are not equivalent.

I have the feeling you consider is_kdump_kernel() equivalent to
"/proc/vmcore" being present and not really saying anything about
whether kdump is active ?

Regards
Alex