Re: BUG_ON() vs ASSERT()

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Sep 12, 2016 at 09:23:41AM -0600, Jan Beulich wrote:
> All,
> 
> in
> https://lists.xenproject.org/archives/html/xen-devel/2016-09/msg01201.html
> and
> https://lists.xenproject.org/archives/html/xen-devel/2016-09/msg01210.html
> Andrew basically suggests that we should switch away from using
> ASSERT() and over to BUG_ON() in perhaps quite broad a set of
> cases. And honestly I'm not convinced of this: We've been adding
> quite a few ASSERT()s over the last years with the aim of doing
> sanity checking in debug builds, without adding overhead to non-
> debug builds. I can certainly see possible cases where using
> BUG_ON() to prevent further possible damage is appropriate, but
> I don't think we should overdo here.
> 
> Thanks for other's opinions,

I am in the mindset that ASSERTS are in the cases where a check
has been done earlier and the ASSERT is more of a catch if we ended up
somehow in the wrong state. We can then slowly follow the breadcrumbs to
see what changed the state. In other words - something that the hypervisor
has checked for and that invariant should have not changed.

But a BUG_ON is in the same category - it should not have happend.

Perhaps the distinction is that for ASSERTS() it is to catch me messing
things up. While BUG_ON() is something (or somebody) else messing things up.

It is kind of hard to describe the semantic of an ASSERT vs BUG_ON now
that I think of it ..

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