linux-kernel - Re: [PATCH] uart: fix race between uart_put_char() and uart

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Date:   Wed, 6 Jun 2018 15:42:07 -0600
From:   Tycho Andersen <tycho@...ho.ws>
To:     "Serge E. Hallyn" <serge@...lyn.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uart: fix race between uart_put_char() and
 uart_shutdown()

On Mon, Jun 04, 2018 at 10:59:36PM -0500, Serge E. Hallyn wrote:
> Quoting Tycho Andersen (tycho@...ho.ws):
> > Unfortunately, I don't have any insightful thoughts about how to test this.
> > Ideas are appreciated :)
> 
> I wonder whether there is something we can do with qemu -serial pipe: ?

Good idea. I couldn't get tty_put_char() to trigger nicely, but I just
hard coded one to occur, so at least now I know that this doesn't
deadlock when called normally.

Another suggestion Serge gave off list was to write a kernel module
that implemented a driver. I'll see about doing that to see if I can
force the original crash.

> > Signed-off-by: Tycho Andersen <tycho@...ho.ws>
> 
> Acked-by: Serge Hallyn <serge@...lyn.com>

Thanks!

Tycho