[Crash-utility] [PATCH] netdump, diskdump: address the issue caused by no NT_PRSTATUS notes

[Dave Anderson]

----- Original Message -----
> Hello Dave,
> 
> I have three patches today.
> 
> The 1st and 2nd patches address the issue that vmcore has no NT_PRSTATUS
> notes.
> 
> - The 1st patch makes crash consider the case where the number of NT_PRSTATUS notes
> is 0. Without this patch, crash leads to NULL pointer dereference when
> using bt command for active tasks.
> 
> - The 2nd patch makes crash pass boot-time sanity check to nr_cpus memebr of diskdump
> header on x86 and x86_64 if it is 0. On both architectures, we can get cpu
> information from memory part. In fact, the value of nr_cpus member is not used
> except for the sanity check.

I'm not sure whether this accomplishes much?  If the vmcore is an x86/x86_64 
compressed kdump, then it will not "goto err", because it would not be DISKDUMP_VALID().
So AFAICT, this patch only changes things to allow the old-style "diskdump" 
vmcore to continue.  But you're right, x86/x86_64 should be allowed to continue
regardless whether the nr_cpus value is incorrectly set to 0.
 
> I saw the situation where vmcore with no NT_PRSTATUS notes is generated, on Xen HVM,
> where the version of kexec not supporting Xen HVM. It determins if system is Xen Dom0
> wrongly and uses interface for Dom0. As a result, vmcore doesn't contain any
> NT_PRSTATUS note.
> 
> When converting this vmcore using makedumpfile, nr_cpus member of diskdump header of
> the resulted vmcore is 0. So the 2nd patch is needed.
> 
> The 3rd patch is differnet from the above two, fixing potencial bug in panic task
> detection code, which I found during investigation for the above two patches.
> But sorry, I didn't test this yet.
> 
> I made every patch on top of crash version 6.1.0.
> 
> Thanks.
> HATAYAMA, Daisuke

Queued for crash-6.1.1.

Thanks,
  Dave