Re: [RFC] drm/tests: annotate intentional stack trace in drm_test_rect_calc_hscale()

[Maxime Ripard]

Hi Dan,

On Wed, Nov 15, 2023 at 05:42:17PM -0500, Dan Carpenter wrote:
> On Mon, Nov 06, 2023 at 02:58:12PM +0100, mripard@xxxxxxxxxx wrote:
> > > But a similar thing is happening here where we have so many bogus
> > > warnings that we missed a real bug.
> > 
> > IIRC, there was a similar discussion for lockdep issues. IMO, any
> > (unintended) warning should trigger a test failure.
> > 
> > I guess that would require adding some intrumentation to __WARN somehow,
> > and also allowing tests to check whether a warning had been generated
> > during their execution for tests that want to trigger one.
> 
> I think this is a good idea.  I was looking at how lockdep prints
> warnings (see print_circular_bug_header()).  It doesn't use WARN() it
> prints a bunch of pr_warn() statements and then a stack trace.  We would
> have to have a increment the counter manually in that situation.
> 
> I'm writing a script to parse a dmesg and collect Oopses.

Do we need to? I was only expecting a boolean to be set or kunit_fail to
be called in the WARN/lockdep warning code path if a test is running?

> So now I know to look for WARN(), lockdep, and KASAN. What other bugs
> formats do we have? Probably someone like the syzbot devs have already
> has written a script like this?

I think you got most of it covered, I can't think of any other source of
failure right now.

Maxime

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