Message-ID: <41774E20.8000309@nortelnetworks.com>
Date: Wed, 20 Oct 2004 23:50:24 -0600
From: Chris Friesen <cfriesen@nortelnetworks.com>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: Michael Clark <michael@metaparadigm.com>, linux-kernel@vger.kernel.org
Subject: Re: UDP recvmsg blocks after select(), 2.6 bug?
References: <20041016062512.GA17971@mark.mielke.cc> <MDEHLPKNGKAHNMBLJOLKMEONPAAA.davids@webmaster.com> <20041017133537.GL7468@marowsky-bree.de> <cl6lfq$jlg$1@terminus.zytor.com> <4176DF84.4050401@nortelnetworks.com> <4176E001.1080104@zytor.com> <41772674.50403@metaparadigm.com> <417736C0.8040102@zytor.com> <417743EF.90604@nortelnetworks.com> <417744FD.1000008@zytor.com>
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H. Peter Anvin wrote:
>> H. Peter Anvin wrote:
>>
>>> The whole point is that it doesn't break the *documented* interface.

> I'm talking about returning -1, EIO.


Ah.  By "it", I thought you meant the current performance optimizations, not the 
EIO.  My apologies.

I think returning EIO is suboptimal, as it is not an expected error value for 
recvmsg().  (It's not listed in the man pages for recvmsg() or ip.)  It would 
certainly work for new apps, but probably not for many existing binaries.

On the other hand, if you simply do the checksum verification at select() time 
for blocking sockets, then the existing binaries get exactly the behaviour they 
expect.

Chris
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