linux-kernel - Re: [PATCH v2 3/6] TTY: serial, remove tasklet for tty

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Message-ID: <20110719173401.131e220f@bob.linux.org.uk>
Date:	Tue, 19 Jul 2011 17:34:01 +0100
From:	Alan Cox <alan@...ux.intel.com>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	gregkh@...e.de, jirislaby@...il.com, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] TTY: serial, remove tasklet for tty_wakeup

On Thu, 14 Jul 2011 14:35:12 +0200
Jiri Slaby <jslaby@...e.cz> wrote:

> tty_wakeup can be called from any context. So there is no need to have
> an extra tasklet for calling that. Hence save some space and remove
> the tasklet completely.
> 
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> Cc: Greg Kroah-Hartman <gregkh@...e.de>
> Cc: Alan Cox <alan@...ux.intel.com>
> ---
>  drivers/tty/serial/serial_core.c |   20 +-------------------
>  include/linux/serial_core.h      |    1 -
>  2 files changed, 1 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/tty/serial/serial_core.c
> b/drivers/tty/serial/serial_core.c index 2cbf1bd..4786232 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -72,7 +72,7 @@ void uart_write_wakeup(struct uart_port *port)
>  	 * closed.  No cookie for you.
>  	 */
>  	BUG_ON(!state);
> -	tasklet_schedule(&state->tlet);
> +	tty_wakeup(state->port.tty);

Probably worth noting that this is only safe if the uart locks are held
and because of the current lock/ref drop combinations in the
serial_core code otherwise it can race with hangup...
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