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From: David Howells <dhowells@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: dhowells@redhat.com, "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	netdev <netdev@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Marc Dionne <marc.dionne@auristor.com>,
	linux-afs@lists.infradead.org,
	syzbot <syzkaller@googlegroups.com>
Subject: Re: [PATCH net] rxrpc: fix a race in rxrpc_exit_net()
Date: Fri, 08 Apr 2022 07:41:30 +0100	[thread overview]
Message-ID: <583132.1649400090@warthog.procyon.org.uk> (raw)
In-Reply-To: <20220404183439.3537837-1-eric.dumazet@gmail.com>

Hi Eric,

[Note that your patch is appl/octet-stream for some reason.]

> 	rxnet->live = false;
> -	del_timer_sync(&rxnet->peer_keepalive_timer);
>  	cancel_work_sync(&rxnet->peer_keepalive_work);
> +	del_timer_sync(&rxnet->peer_keepalive_timer);

That fixes that problem, but introduces another.  The timer could be in the
throes of queueing the worker:

	CPU 1			CPU 2
	====================	=====================
				if (rxnet->live)
				<INTERRUPT>
	rxnet->live = false;
 	cancel_work_sync(&rxnet->peer_keepalive_work);
				rxrpc_queue_work(&rxnet->peer_keepalive_work);
	del_timer_sync(&rxnet->peer_keepalive_timer);

I think keeping the first del_timer_sync() that you removed and the one after
the cancel would be sufficient.

David


  parent reply	other threads:[~2022-04-08  6:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-04 18:34 [PATCH net] rxrpc: fix a race in rxrpc_exit_net() Eric Dumazet
2022-04-06 13:10 ` patchwork-bot+netdevbpf
2022-04-08  6:41 ` David Howells [this message]
2022-04-12  8:06 ` David Howells
2022-04-12 16:33   ` Eric Dumazet

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