netdev - Re: [PATCH] rxrpc_find_service_conn_rcu: use read_seqbegin() rather than read_seqbegin_or

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Message-ID: <20231101205238.GI1957730@ZenIV>
Date: Wed, 1 Nov 2023 20:52:38 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Oleg Nesterov <oleg@...hat.com>
Cc: David Howells <dhowells@...hat.com>,
	Marc Dionne <marc.dionne@...istor.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Chuck Lever <chuck.lever@...cle.com>, linux-afs@...ts.infradead.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rxrpc_find_service_conn_rcu: use read_seqbegin() rather
 than read_seqbegin_or_lock()

On Wed, Nov 01, 2023 at 09:23:03PM +0100, Oleg Nesterov wrote:

> Yes this is confusing. Again, even the documentation is wrong! That is why
> I am trying to remove the misuse of read_seqbegin_or_lock(), then I am going
> to change the semantics of need_seqretry() to enforce the locking on the 2nd
> pass.

What for?  Sure, documentation needs to be fixed, but *not* in direction you
suggested in that patch.

Why would you want to force that "switch to locked on the second pass" policy
on every possible caller?