Messages in this thread | | | From | "Dan Akunis" <> | Subject | Re: [REGRESSION] Select hang with zero sized UDP packets | Date | Wed, 24 Aug 2016 11:22:09 +0300 |
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When select wakes up on a UDP socket, user is expecting to get data. Getting 0 from recvfrom() or whatever read function she uses, is a wrong attitude. I agree with David.
The unit test that expects select to wake up is wrong and should be changed.
-----Original Message----- From: David Miller Sent: Tuesday, August 23, 2016 9:25 PM 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
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.
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