Re: New diagnostic routine - mutex_ownable()

[Paul Goyette <paul%whooppee.com@localhost>]

On Sun, 30 Apr 2017, coypu%sdf.org@localhost wrote:

> I feel like we mostly care about adaptive mutexes, how about this
> alternate suggestion?
>
> mutex_adaptive_owned(kmutex_t * mtx)
> {
> 	if (mtx == NULL)
> 		return 0;
>
> 	KASSERT(MUTEX_ADAPTIVE_P(mtx));
> 	return MUTEX_OWNER(mtx->mtx_owner) == (uintptr_t)curlwp;
> }

It seems reasonable, as a general case, if the caller knows that the
mutex is indeed adaptive.  (But wouldn't the NULL check for the mtx
be better as a KASSERT rather than returning "not-held"?)

For my use-case, it is unknown whether the caller-provided mutex is
adaptive vs spin.  I would expect it to be adaptive, and indeed, for
all currently-planned uses of localcount(9), this would be an adaptive
mutex.  But there is no reason for the localcount(9) stuff to require
an adaptive mutex here.

Thus, I would not be able to use your alternate suggestion.



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