From: Oleg Nesterov <oleg@redhat.com>
To: 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>
Cc: 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: Fri, 27 Oct 2023 12:00:47 +0200 [thread overview]
Message-ID: <20231027100047.GA30884@redhat.com> (raw)
In-Reply-To: <20231027095842.GA30868@redhat.com>
On 10/27, Oleg Nesterov wrote:
>
> read_seqbegin_or_lock() makes no sense unless you make "seq" odd
> after the lockless access failed. See thread_group_cputime() as
> an example, note that it does nextseq = 1 for the 2nd round.
See also
[PATCH 1/2] seqlock: fix the wrong read_seqbegin_or_lock/need_seqretry documentation
https://lore.kernel.org/all/20231024120808.GA15382@redhat.com/
> So this code can use read_seqbegin() without changing the current
> behaviour.
I am trying to remove the misuse of read_seqbegin_or_lock(),
then I am going to turn need_seqretry() into
static inline int need_seqretry(seqlock_t *lock, int *seq)
{
int ret = !(*seq & 1) && read_seqretry(lock, *seq);
if (ret)
*seq = 1; /* make this counter odd */
return ret;
}
Oleg.
next prev parent reply other threads:[~2023-10-27 10:01 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 [this message]
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
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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