Re: Passive serialization support in the pool allocator

[Lars Reichardt <lars%paradoxon.info@localhost>]

On Tue, 21 Dec 2021 18:19:56 -0800
Jason Thorpe <thorpej%me.com@localhost> wrote:

> An #ifdef that Taylor added in the new DRM code was bugging me,
> because a similar situation already existed in the NetBSD kernel,
> whereby the type stability of a object’s backing memory (the iam
> existentium case being LWPs) was required for a passively-serialized
> weak reference to work.  The LWP pool cache had a hack to handle it,
> and the hack was propagated to the new DRM code under an “#ifdef
> __NetBSD__”.
> 
> I initially fixed this by adding a “pre-destruct” callback that could
> be optionally set for a pool cache, but after further discussion, it
> seemed like having direct knowledge of passive serialization
> synchronization points in the allocator was a better solution, so
> here is a diff that implements it for you review.
> 
> 	https://www.netbsd.org/~thorpej/pool-pser-diff.txt
> 
> Please comment ASAP, because I want to ride a kernel version bump.
> 
> -- thorpej
> 

LGTM.

Giving the pool knowledge about passive serialization makes it (in my
understanding at least) more easy understandable and keeps the
pool/pool_cache api cleaner.

para


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