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SubjectRe: [PATCH v2 1/1] Char: tty, fix tty_port_block_til_ready waiting
On Thu, 18 Jun 2009 09:46:13 +0200
Jiri Slaby <jirislaby@gmail.com> wrote:

> Use DEFINE_WAIT instead DECLARE_WAITQUEUE, because we use
> prepare/finish_wait since commit
> 3e3b5c087799e536871c8261b05bc28e4783c8da
> (tty: use prepare/finish_wait)
>
> Otherwise we would oops in finish_wait.
>

<scratches head for a while>

OK, here's a better changelog:

Since commit 3e3b5c087799e536871c8261b05bc28e4783c8da ("tty: use
prepare/finish_wait"), tty_port_block_til_ready() is using
prepare_to_wait()/finish_wait(). Those functions require that
the wait_queue_t be initialised with .func=autoremove_wake_function,
via DEFINE_WAIT().

But the conversion from DECLARE_WAITQUEUE() to DEFINE_WAIT() was
not made, so this code will oops in finish_wait().

>
> diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
> index 62dadfc..4e862a7 100644
> --- a/drivers/char/tty_port.c
> +++ b/drivers/char/tty_port.c
> @@ -193,7 +193,7 @@ int tty_port_block_til_ready(struct tty_port *port,
> {
> int do_clocal = 0, retval;
> unsigned long flags;
> - DECLARE_WAITQUEUE(wait, current);
> + DEFINE_WAIT(wait);
> int cd;
>
> /* block if port is in the process of being closed */

Why is nobody reporting the oopses?


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