Re: [Qemu-devel] [patch] Fix block I/O hang.

[Gerd Hoffmann <kraxel@redhat.com>]

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‐ sequent read blocks.  This could for
>    example happen when data has arrived but upon  examination  has  wrong
>    checksum  and  is  discarded.   There  may  be other circumstances in which
>    a file descriptor is spuriously reported as ready.  Thus it may be safer 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