[PATCH V4] kernel, add bug_on_warn

[Andi Kleen]

On Fri, Oct 24, 2014 at 08:53:27AM -0400, Prarit Bhargava wrote:
> There have been several times where I have had to rebuild a kernel to
> cause a panic when hitting a WARN() in the code in order to get a crash
> dump from a system.  Sometimes this is easy to do, other times (such as
> in the case of a remote admin) it is not trivial to send new images to the
> user.
> 
> A much easier method would be a switch to change the WARN() over to a
> BUG().  This makes debugging easier in that I can now test the actual
> image the WARN() was seen on and I do not have to engage in remote
> debugging.

IMHO this would be better and far more generically done with kdb. 
You would need two things:

- Extend the break point command to run another command on a break point.
- Add a command line (or possibly /proc) option to execute some kdb commands at
kernel boot.

Then just set a break point on the warn function and execute magic sysrq c
from kdb.

-Andi