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Author neologix
Recipients neologix, xdegaye
Date 2011-11-01.21:01:05
SpamBayes Score 9.814821e-10
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Message-id <1320181266.08.0.55662939097.issue13310@psf.upfronthosting.co.za>
In-reply-to
Content
Hello Xavier,

> select (an poll) returns a read event and an exceptional condition 
> for the socket, but there is no normal data to read, only out-of-band
> data.

That's against POSIX:
"""
POLLIN
Data other than high-priority data may be read without blocking. For STREAMS, this flag is set in revents even if the message is of zero length. 
"""

And indeed, that's a known kernel regression introduced in 2.6.28, and fixed by this commit:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b634f87522dff87712df8bda2a6c9061954d552a
http://kerneltrap.org/mailarchive/linux-netdev/2010/3/15/6271951

Note that there might still be a problem with the current code:
recv() can return EAGAIN on a FD reported readable/writable by select() (for example if the network stack received an input packet and then discards it because of an invalid checksum, or because the output socket buffer has room left but not enough to accomodate the packet we're trying to send): I'll have to think a bit to see if we can do something about this, but that's another issue.
Closing as invalid.
History
Date User Action Args
2011-11-01 21:01:06neologixsetrecipients: + neologix, xdegaye
2011-11-01 21:01:06neologixsetmessageid: <1320181266.08.0.55662939097.issue13310@psf.upfronthosting.co.za>
2011-11-01 21:01:05neologixlinkissue13310 messages
2011-11-01 21:01:05neologixcreate