Re: do_tty_write() can block even with O_NONBLOCK?

From: Alan Cox
Date: Wed May 02 2007 - 11:59:28 EST


On Wed, 2 May 2007 11:17:00 -0400
Dave Johnson <djohnson+linux-kernel@xxxxxxxxxxxxxxxxxxxxxx> wrote:

>
> I have two processes with the same tty open, one opens blocking and
> one opens nonblocking.
>
> If the blocking process blocks doing a write (due to flow control,
> just going to fast, etc...) the nonblocking process will also block
> when it writes until the blocking process unblocks.
>
> This seems to occur because do_tty_write() isn't checking for
> O_NONBLOCK when taking the tty's write mutex.
>
>
> Signed-off-by: Dave Johnson <djohnson+linux-kernel@xxxxxxxxxxxxxxxxxxxxxx>

Acked-by: Alan Cox <alan@xxxxxxxxxx>

Looks fine to me.
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