Re: [PATCH] POLL_OUT in ttys, misc bug fix

From: Marcelo Tosatti (marcelo@conectiva.com.br)
Date: Thu Apr 04 2002 - 14:56:22 EST


Sapan,

Have you actually tested the SIGIO POLL_OUT changes with an userspace app?

Thanks

On Wed, 27 Mar 2002, Sapan J . Bhatia wrote:

> Hello,
>
> While fixing a flow control bug that truncated output to a terminal in
> User Mode Linux, I noticed that the tty drivers only send POLL_IN on new
> data being available but not POLL_OUT when the device is ready for new
> data.
>
> This patch fixes the bug in the line discipline and the pty driver.
>
> Also, there's another minor bug in n_tty.c where write_chan returns
> on a (retvalue < 0) unconditionally. This is a problem, since the type of
> IO (BLOCKING / NON_BLOCKING) is stored in the tty, and if the console driver
> returns a -EAGAIN (eg. in UML on getting an EAGAIN from the host kernel),
> write_chan returns even in the case of a blocking write, which is wrong
> since the process doesn't expect it.
>
> Regards,
> Sapan
>
>

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