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

[Davide Italiano]

On Thu, Sep 25, 2014 at 11:09 AM, Ian Lepore <ian at freebsd.org> wrote:
> On Thu, 2014-09-25 at 10:51 -0700, Davide Italiano wrote:
>> On Thu, Sep 25, 2014 at 9:14 AM, Adrian Chadd <adrian at freebsd.org> wrote:
>> > Hi,
>> >
>> > Please bring in KASSERT_WARN().
>> >
>> > I'm grown up enough to use KASSERT_WARN() along with handling the
>> > invariant check myself in code. Having KASSERT_WARN() means I can add
>> > in this rather than printf()s or device_printf()'s with various knobs
>> > to remove it.
>> >
>> > (This is absolutely _not_ the "should KASSERT() optionally just log"
>> > argument. I'm not going to get into that a second time.)
>> >
>> >
>>
>> If you put a KASSERT() inside your code -- probably you should be
>> careful enough to put that iff you're sure that it should be always
>> verified. No exceptions.
>> People tend to be very lazy (including me). I don't expect everybody
>> diligently upgrading KASSERT_WARN to KASSERT. So KASSERT_WARN start
>> becoming more and more widespread, and people realize all of these
>> need to be upgraded to KASSERT or removed. This generally happens
>> after years. Yet. Another. Crusade.
>> There's a lot of work in the kernel to remove old/wrong/naive  KPI
>> from the kernel. jhb@ is looking at timeout()-> callout() conversion.
>> I'm personally looking at dev_clone() removal. There are a lot of
>> other examples.
>> Adding KASSERT_WARN is a step backward, not a step forward, IMHO.
>> That said, if you want to pollute the kernel, fine. I expressed my
>> opinion, and I'm personally not happy about this, but I never stated
>> I'm gonna stop you from doing that.
>>
>> Thanks,
>>
>> --
>
> IMO, this entire argument is ridiculous.  Some conditions are so insane
> that you've got to stop immediately rather than make things worse.
> Other conditions indicate problems, but the code can recover or
> otherwise continue to operate safely.  Trying to define every possible
> anomalous condition as either fatal or not worth mentioning is insane.
>
> Everyone is free to write code such as
>
> #ifdef INVARIANTS
>   if (some_condition)
>     printf("whatever warning\n");
> #endif
>
> So let's be clear here:  the objections are to spelling that code
> sequence KASSERT_WARN.  If you object, please explain what's wrong with
> that spelling and how you would prefer it to be spelled.
>
> -- Ian
>
>

Take the assert out of the name. Call it DEBUG_WARN, or something else
if you like.
assert as a pretty *clear* and specific semantic, no need to mess
around with it.

Thanks,

-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare