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

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Message-ID: <104932.1700142106@warthog.procyon.org.uk>
Date:   Thu, 16 Nov 2023 13:41:46 +0000
From:   David Howells <dhowells@...hat.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     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>,
        Al Viro <viro@...iv.linux.org.uk>,
        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()

Oleg Nesterov <oleg@...hat.com> wrote:

> So do you agree that
> 
> 	- the usage of read_seqbegin_or_lock/need_seqretry in
> 	  this code makes no sense because read_seqlock_excl()
> 	  is not possible

Not exactly.  I think it should take a lock on the second pass.

> 	- this patch doesn't change the current behaviour but
> 	  simplifies the code and makes it more clear

That is true.

David