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From: David Miller <davem@davemloft.net>
To: labbott@redhat.com
Cc: kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org,
	kaber@trash.net, samanthakumar@google.com, willemb@google.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [REGRESSION] Select hang with zero sized UDP packets
Date: Tue, 23 Aug 2016 11:25:15 -0700 (PDT)	[thread overview]
Message-ID: <20160823.112515.318902967155957764.davem@davemloft.net> (raw)
In-Reply-To: <08d225a8-e98f-c0c6-271d-acc2584347fc@redhat.com>

From: Laura Abbott <labbott@redhat.com>
Date: Tue, 23 Aug 2016 10:53:26 -0700

> Fedora received a report[1] of a unit test failing on Ruby when using
> the
> 4.7 kernel. This was a test to send a zero sized UDP packet. With the
> 4.7 kernel, the test now timing out on a select instead of completing.
> The reduced ruby test is
> 
>   def test_udp_recvfrom_nonblock
>     u1 = UDPSocket.new
>     u2 = UDPSocket.new
>     u1.bind("127.0.0.1", 0)
>     u2.send("", 0, u1.getsockname)
>     IO.select [u1]  # test gets stuck here
>   ensure
>     u1.close if u1
>     u2.close if u2
>   end

Well, if there is no data, should select really wake up?

I think it's valid not to.

  reply	other threads:[~2016-08-23 18:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-23 17:53 [REGRESSION] Select hang with zero sized UDP packets Laura Abbott
2016-08-23 18:25 ` David Miller [this message]
2016-08-23 19:03   ` Eric Dumazet
2016-08-23 20:06     ` Laura Abbott
2016-08-23 20:42       ` Eric Dumazet
2016-08-23 20:53       ` [PATCH net] udp: fix poll() issue with zero sized packets Eric Dumazet
2016-08-23 20:56         ` Eric Dumazet
2016-08-23 20:59         ` [PATCH v2 " Eric Dumazet
2016-08-23 23:39           ` David Miller
2016-08-24  8:22   ` [REGRESSION] Select hang with zero sized UDP packets Dan Akunis
2016-08-24 13:02     ` Eric Dumazet
2016-08-24 13:42     ` One Thousand Gnomes

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