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From: Florian Westphal <fw@strlen.de>
To: Jozsef Kadlecsik <kadlec@netfilter.org>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
	Florian Westphal <fw@strlen.de>, Phil Sutter <phil@nwl.cc>,
	netfilter-devel@vger.kernel.org
Subject: Re: [nf PATCH v2 8/8] netfilter: nf_tables: Add locking for NFT_MSG_GETSETELEM_RESET requests
Date: Thu, 28 Sep 2023 22:09:46 +0200	[thread overview]
Message-ID: <20230928200946.GB28176@breakpoint.cc> (raw)
In-Reply-To: <fedeecd9-b03-789-bc6c-21a697fc29d@netfilter.org>

Jozsef Kadlecsik <kadlec@netfilter.org> wrote:
> On Thu, 28 Sep 2023, Pablo Neira Ayuso wrote:
> > One concern might be deadlock due to reordering, but I don't see how
> > that can happen.
> 
> The same problem exists ipset: when a set is listed/saved (dumped), 
> concurrent destroy/rename/swap for the same set must be excluded. As 
> neither spinlock nor mutex helps, a reference counter is used: the start 
> of the dump increases it and by checking it all concurrent events can 
> safely be rejected by returning EBUSY.

Thanks for sharing!

I assume that means that a dumper that starts a dump, and then
goes to sleep before closing the socket/finishing the dump can
block further ipset updates, is that correct?

(I assume so, I don't see a solution that doesn't trade one problem
 for another).

  reply	other threads:[~2023-09-28 20:09 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-28 16:52 [nf PATCH v2 0/8] Introduce locking for reset requests Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 1/8] netfilter: nf_tables: Don't allocate nft_rule_dump_ctx Phil Sutter
2023-09-28 18:49   ` Pablo Neira Ayuso
2023-09-29 10:15     ` Phil Sutter
2023-09-28 19:00   ` Florian Westphal
2023-09-29 10:13     ` Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 2/8] netfilter: nf_tables: Introduce nf_tables_getrule_single() Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 3/8] netfilter: nf_tables: Add locking for NFT_MSG_GETRULE_RESET requests Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 4/8] netfilter: nf_tables: Introduce struct nft_obj_dump_ctx Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 5/8] netfilter: nf_tables: Introduce nf_tables_getobj_single Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 6/8] netfilter: nf_tables: Add locking for NFT_MSG_GETOBJ_RESET requests Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 7/8] netfilter: nf_tables: Pass reset bit in nft_set_dump_ctx Phil Sutter
2023-09-28 18:53   ` Pablo Neira Ayuso
2023-09-29 10:08     ` Phil Sutter
2023-09-29 10:15       ` Pablo Neira Ayuso
2023-09-29 10:18         ` Phil Sutter
2023-09-29 10:56           ` Pablo Neira Ayuso
2023-09-29 11:12             ` Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 8/8] netfilter: nf_tables: Add locking for NFT_MSG_GETSETELEM_RESET requests Phil Sutter
2023-09-28 17:46   ` Florian Westphal
2023-09-28 18:47     ` Pablo Neira Ayuso
2023-09-28 18:57       ` Florian Westphal
2023-09-28 19:04         ` Pablo Neira Ayuso
2023-09-28 19:21           ` Florian Westphal
2023-09-28 20:07             ` Florian Westphal
2023-09-29 11:25               ` Phil Sutter
2023-09-29 11:30                 ` Florian Westphal
2023-09-29 11:45                   ` Phil Sutter
2023-09-28 19:39           ` Jozsef Kadlecsik
2023-09-28 20:09             ` Florian Westphal [this message]
2023-09-28 20:25               ` Jozsef Kadlecsik
2023-09-29 11:03     ` Phil Sutter
2023-09-28 18:51   ` Pablo Neira Ayuso
2023-09-29 10:28     ` Phil Sutter

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