netdev - Re: [PATCH net 1/6] netfilter: nf_tables: report use refcount overflow

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Date: Thu, 06 Jul 2023 11:01:42 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Pablo Neira Ayuso <pablo@...filter.org>, netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org, 
	edumazet@...gle.com
Subject: Re: [PATCH net 1/6] netfilter: nf_tables: report use refcount
 overflow

On Thu, 2023-07-06 at 01:04 +0200, Pablo Neira Ayuso wrote:
> Overflow use refcount checks are not complete.
> 
> Add helper function to deal with object reference counter tracking.
> Report -EMFILE in case UINT_MAX is reached.
> 
> nft_use_dec() splats in case that reference counter underflows,
> which should not ever happen.

For the records, I also once had the need for an non atomic reference
counters implementing sanity checks on underflows/overflows. I resorted
to use plain refcount_t, since the atomic op overhead was not
noticeable in my use-case.

[not blocking this series, just thinking aloud] I'm wondering if a
generic, non-atomic refcounter infra could be useful?

Cheers,

Paolo