svn commit: r238907 - projects/calloutng/sys/kern

[Attilio Rao]

On Mon, Jul 30, 2012 at 9:39 PM, Attilio Rao <attilio at freebsd.org> wrote:
> On Mon, Jul 30, 2012 at 4:31 PM, Andriy Gapon <avg at freebsd.org> wrote:
>> on 30/07/2012 18:04 Attilio Rao said the following:
>>> On 7/30/12, Andriy Gapon <avg at freebsd.org> wrote:
>>>> on 30/07/2012 17:56 Attilio Rao said the following:
>>>>> More explicitly, I think such combination TDP_NOSLEEPING +
>>>>> TDP_NOBLOCKING (name invented) should be set on entering the interrupt
>>>>> context, not only related to this part of callouts. This would be a
>>>>> very good help for catching buggy situations.
>>>>
>>>> Something very tangential.  I think it would also be nice to check if a
>>>> thread has
>>>> any(?) locks held when returning to userland.
>>>
>>> This happens already for INVARIANTS case, with td_locks counters.
>>> In the !INVARIANTS case, this doesn't happen because you don't want to
>>> add the burden to bump td_locks for the fast case and I think it is a
>>> good approach.
>>
>> Ah, I missed that, thank you.
>> BTW, it seems that td_locks is checked twice in normal syscallret() path: once in
>> syscallret() itself and then in userret().  On this note, would it make sense to
>> move the whole nine yards of asserts from syscallret() to userret()?
>> I mean it might make sense to have those checks (td_critnest, td_pflags) in other
>> paths to userland.
>
> Nice catch.
> The checks were added to syscallret() in r208453. While this is fine,
> I think that putting them in userret() may give them more exposure and
> cover also cases like traps which are not covered right now.
> If you want to make a patch that moves these conditions in userret()
> I'd be in favor of it.

More specifically, what do you think about this patch?:
http://www.freebsd.org/~attilio/userret_diag.patch

Of course I moved the XEN par too before the checks.
The patch survived to few consecutive and parallel buildworlds, FWIW.

Attilio


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