From: Al Viro <viro@zeniv.linux.org.uk>
To: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>,
Marc Dionne <marc.dionne@auristor.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Chuck Lever <chuck.lever@oracle.com>,
linux-afs@lists.infradead.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rxrpc_find_service_conn_rcu: use read_seqbegin() rather than read_seqbegin_or_lock()
Date: Wed, 1 Nov 2023 22:48:55 +0000 [thread overview]
Message-ID: <20231101224855.GJ1957730@ZenIV> (raw)
In-Reply-To: <20231101215214.GD32034@redhat.com>
On Wed, Nov 01, 2023 at 10:52:15PM +0100, Oleg Nesterov wrote:
> > Why would you want to force that "switch to locked on the second pass" policy
> > on every possible caller?
>
> Because this is what (I think) read_seqbegin_or_lock() is supposed to do.
> It should take the lock for writing if the lockless access failed. At least
> according to the documentation.
Not really - it's literally seqbegin or lock, depending upon what the caller
tells it... IMO the mistake in docs is the insistence on using do-while
loop for its users.
Take a look at d_walk() and try to shoehorn that into your variant. Especially
the D_WALK_NORETRY handling...
next prev parent reply other threads:[~2023-11-01 22:49 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-27 9:58 [PATCH] rxrpc_find_service_conn_rcu: use read_seqbegin() rather than read_seqbegin_or_lock() Oleg Nesterov
2023-10-27 10:00 ` Oleg Nesterov
2023-11-01 15:45 ` David Howells
2023-11-01 20:23 ` Oleg Nesterov
2023-11-01 20:40 ` Oleg Nesterov
2023-11-01 21:22 ` David Howells
2023-11-01 22:38 ` Oleg Nesterov
2023-11-01 20:52 ` Al Viro
2023-11-01 21:52 ` Oleg Nesterov
2023-11-01 22:48 ` Al Viro [this message]
2023-11-01 23:17 ` Oleg Nesterov
2023-11-01 21:20 ` David Howells
2023-11-01 22:15 ` Oleg Nesterov
2023-11-01 22:29 ` Oleg Nesterov
2023-11-16 13:18 ` Oleg Nesterov
2023-11-16 13:41 ` David Howells
2023-11-16 14:19 ` Oleg Nesterov
2023-11-16 15:02 ` David Howells
2023-11-16 15:06 ` Oleg Nesterov
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