[Crash-utility] [PATCH] s390: Fix backtrace code

[Michael Holzheu]

Hi Dave,

On Fri, 2010-02-26 at 10:42 -0500, Dave Anderson wrote:
> > I tested vanilla 2.6.32, RHEL5, SLES10 and SLES11.
> > 
> > But I found a bug with RHEL4:
> 
> OK good -- I'm glad I asked.  I note that RHEL3 doesn't even have
> a "panic_stack" member.  That being the case, this won't work as
> planned:
> 
>         stack_addr = ULONG(lc + MEMBER_OFFSET("_lowcore", stack_name));
>         if (stack_addr == 0)
>                 return;
> 
> because MEMBER_OFFSET() will return a -1, which will get used as
> an offset to add to "lc", and will quietly read the wrong data.
> 

Therefore I do this check before:

	if (!MEMBER_EXISTS("_lowcore", stack_name))
		return;

Michael