Re: [PATCH] Convert serial_core oopses to BUG_ON

[Pavel Machek <pavel@ucw.cz>]

Hi!

> With reference to these two bugs:
> 
> 	http://bugzilla.kernel.org/show_bug.cgi?id=5958
> 	http://bugzilla.kernel.org/show_bug.cgi?id=6131
> 
> it seems that folk are under the impression that serial_core is
> responsible for these bugs.  It isn't.
> 
> Calling serial functions to flush buffers, or try to send more data
> after the port has been closed or hung up is a bug in the code doing
> the calling, not in the serial_core driver.
> 
> Make this explicitly obvious by adding BUG_ON()'s.

They did not trigger for me, altrough my own traps do.

> diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
> --- a/drivers/serial/serial_core.c
> +++ b/drivers/serial/serial_core.c
> @@ -521,6 +532,12 @@ static void uart_flush_buffer(struct tty
>  	struct uart_port *port = state->port;
>  	unsigned long flags;
>  
> +	/*
> +	 * This means you called this function _after_ the port was
> +	 * closed.  No cookie for you.
> +	 */
> +	BUG_ON(!state);
> +
>  	DPRINTK("uart_flush_buffer(%d) called\n", tty->index);
>  
>  	spin_lock_irqsave(&port->lock, flags);
> 

This is one I'm hitting. Actually I'm hitting my own check few lines
down:

        if (!state->info)
                printk(KERN_CRIT "no state->info\n");
        else uart_circ_clear(&state->info->xmit);
        spin_unlock_irqrestore(&port->lock, flags);
        tty_wakeup(tty);

... simply not doing uart_circ_clear() at all makes system
survive... so this could be made into WARN()...

								Pavel
-- 
Web maintainer for suspend.sf.net (www.sf.net/projects/suspend) wanted...