Re: possible regression with pty.c commit

From: Alan Cox
Date: Sat Jul 11 2009 - 18:24:37 EST


On Sat, 11 Jul 2009 22:15:56 +0300
Sergey Senozhatsky <sergey.senozhatsky@xxxxxxx> wrote:

> Hello,
> commit d945cb9cce20ac7143c2de8d88b187f62db99bdc ("pty: Rework the pty layer to use the normal buffering logic")
> seems to brake kdesu.

This looks like a timing bug in kdesu at first glance but it may be more
complex.

> close(11) = 0

We close one side of the pty/tty pair

> write(10, "stop", 4) = 4
> write(10, "\n", 1) = 1
> fcntl64(10, F_GETFL) = 0x2 (flags O_RDWR)
> read(10, 0xbf840858, 255) = -1 EIO (Input/output error) <<<<<<<<<

At this point the other side is closed, we have a hangup and the read
correctly I think gets -EIO.

I will have a look at kdesu on Monday, I've got Fedora setups here so
hopefully I can reproduce it simply.
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