Re: elog(DEBUG2 in SpinLocked section.

Hi,

On 2020-06-03 00:36:34 -0400, Tom Lane wrote:
> Should we think about adding automated detection of this type of
> mistake?  I don't like the attached as-is because of the #include
> footprint expansion, but maybe we can find a better way.

I experimented with making the compiler warn about about some of these
kinds of mistakes without needing full test coverage:

I was able to get clang to warn about things like using palloc in signal
handlers, or using palloc while holding a spinlock. Which would be
great, except that it doesn't warn when there's an un-annotated
intermediary function. Even when that function is in the same TU.

Here's my attempt: https://godbolt.org/z/xfa6Es

It does detect things like
    spinlock_lock();
    example_alloc(17);
    spinlock_unlock();

:49:2: warning: cannot call function 'example_alloc' while mutex 'holding_spinlock' is held [-Wthread-safety-analysis]

        example_alloc(17);

        ^

which isn't too bad.

Does anybody think this would be useful even if it doesn't detect the
more complicated cases?

Greetings,

Andres Freund