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Date: Wed, 12 Nov 2008 16:01:06 +0100
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [patch] Fix block I/O hang.
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To: qemu-devel@nongnu.org

Johannes Stezenbach wrote:

> I don't know what kind of fd you're talking about, but the
> Linux select man page says:

pipe.

> BUGS
>    Under Linux, select() may report a socket file descriptor as "ready =
for
>    reading", while nevertheless a sub=E2=80=90 sequent read blocks.  Th=
is could for
>    example happen when data has arrived but upon  examination  has  wro=
ng
>    checksum  and  is  discarded.   There  may  be other circumstances i=
n which
>    a file descriptor is spuriously reported as ready.  Thus it may be s=
afer to
>    use O_NONBLOCK on sockets that should not block.

Unlikely to apply here, I've also found the real problem (see other mail
in this thread).

cheers,
  Gerd