[Crash-utility] [PATCH] Fix warning: multiple active tasks have called die

[Dave Anderson]

----- Original Message -----
> Hi Dave,
> 
> When opening an s390(x) dump where the kernel has panic'ed, I currently
> get the following warnings:
> 
> WARNING: multiple active tasks have called die and/or panic
> WARNING: multiple active tasks have called die
> 
> In task.c we call "foreach bt -t" and check if we find "die" on the stack. When
> doing this on s390 with the "-t" option normally we find multiple die() calls
> for one single task:
> 
> crash> foreach bt -t | grep "die at"
>   [        9ca7f7f0] die at 100f26
>   [        9ca7f8f0] die at 100f26
>   [        9ca7f9b8] die at 100f26
>   [        9ca7fa40] die at 100ee6
>   [        9ca7fa90] die at 100f26
> 
> The current code then assumes that multiple tasks have called die().
> 
> This patch fixes this problem by an additional check that allows multiple
> occurrences of the die() call on the stack (with bt -t) for one task.

Strange -- has this always happened on s390's?  And I wonder why
why there are multiple instances on the stack?  What does the actual
backtrace look like?  In any case, I guess the patch makes sense, 
although I wonder why nobody else has ever reported this.  

By any chance, given that this must be zdump-type dumpfile (?), does 
the "dh_cpu_id" member in the header correlate to the panic cpu?  Or
is there any other way that the panic'ing task can be ascertained from
"S390D" dumpfiles such that get_dumpfile_panic_task() can do the job?

Dave