KASSERT_WARN for asserting malloc(M_WAITOK) not in a non-sleepable thread

[Davide Italiano]

On Wed, Sep 24, 2014 at 6:16 PM, Bryan Drewery <bdrewery at freebsd.org> wrote:
> Hi,
>
> I've placed 2 reviews out in relation to
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193696:
>
> Add KASSERT_WARN which will work just like KASSERT except that no panic
> will occur.  My own expectation would be that any use of it would
> eventually be promoted to a full KASSERT.  It would only be used where
> the impact is not known yet on all hardware/devices.  We don't want to
> go adding a KASSERT and break boot for a whole class of systems.
>
>   https://reviews.freebsd.org/D829 - KASSERT_WARN
>

FYI, I'm not excited about the idea. If you introduce an assert you
want some invariant to not be violated. If it's violated, there's
something clearly going wrong and you need to stop and think about it.
I guess that in most cases is just better fail early, rather than keep
going with the system in a semi-functional state.  Also, please note
that once a KPI is introduced in the kernel, everybody may start
abusing it.
A previous attempt (in my opinion wrong) was made to have KASSERT to
log rather than panic. It actually didn't lead to any benefit,
apparently. FWIW, at least your approach is more fine grained.

--
Davide