Date: Tue, 8 Mar 2005 11:25:13 -0500 (EST)
From: linux-os <linux-os@analogic.com>
Reply-To: linux-os@analogic.com
To: Joerg Pommnitz <pommnitz@yahoo.com>
cc: linux-kernel@vger.kernel.org
Subject: Re: select(2), usbserial, tty's and disconnect
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On Tue, 8 Mar 2005, Joerg Pommnitz wrote:

> Hello all,
> currently it seems that select keeps blocking when the USB device behind
> ttyUSBx gets unplugged. My understanding is, that select should return
> when the next call to one of the operations (read/write) will not block.
> This is certainly true for failing with ENODEV. So, is this an issue
> that will be fixed or should I poll (not the syscall) the device? Or is
> there another way to monitor for a vanishing tty (it should not be USB
> specific).
>
> Thanks in advance
>  Joerg

In principle, you need to set your device handle (socket or fd)
to non-blocking before you use select() or poll(). It was never
resolved if the current behavior is a BUG. Nevertheless, it
is unlikely that it will be fixed because there is the belief
that it is NOT a BUG and even if it is a BUG, programs depend
upon this BUG to work.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.10 on an i686 machine (5537.79 BogoMips).
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