Locking [LWN.net]

Locking

Posted Sep 24, 2024 20:53 UTC (Tue) by roc (subscriber, #30627)
In reply to: Locking by viro
Parent article: Resources for learning Rust for kernel development

The C cleanup-based guards were recently added, in 2023. So the decision was made, by Linus and others, that the advantages outweigh your concerns. I don't see why this needs to be relitigated for Rust.

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Locking

Posted Sep 28, 2024 23:12 UTC (Sat) by viro (subscriber, #7872) [Link] (1 responses)

> The C cleanup-based guards were recently added, in 2023. So the decision was made, by Linus and others, that the advantages outweigh your concerns. I don't see why this needs to be relitigated for Rust.

A nice bit of MBAese, that... Opposition between "advantages" on one hand and "your concerns" on another is particularly charming - the former being implicitly objective and unchanging, while the latter - subjective and theoretical in the best case. Use of passive-with-reference-to-management syntax is also impressive. Well done.

Back in the real world, cleanup.h contains tools that are
1) potentially useful
2) experimental and not well-understood
3) demonstrably dangerous in incautious use - and that's demonstrably, not theoretically. Fresh example: https://lore.kernel.org/lkml/20240927-reset-guard-v1-1-29...

The tools in question have nothing to do with Rust, so their relevance in this thread is, indeed, questionable. Who'd dragged them in, I wonder... <checks> https://lwn.net/Articles/991431/ is where that had happened, so it would be yourself, wouldn't it?

Locking

Posted Sep 29, 2024 7:22 UTC (Sun) by Cyberax (✭ supporter ✭, #52523) [Link]

> 2) experimental and not well-understood

Deferred cleanup has been used in C++ and Go for _decades_ and is very well understood. The main rule is: do NOT mix it with goto-based control. It can even be automated via a simple checkpatch.pl rule.

In that case, the of_node_put should also be rewritten into the guard-style cleanup.