linux-kernel - Re: [PATCH] vt: avoid BUG_ON in con_shutdown when con

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Date:	Thu, 31 Mar 2011 10:58:11 +0100
From:	Alan Cox <alan@...ux.intel.com>
To:	Herton Ronaldo Krzesinski <herton.krzesinski@...onical.com>
Cc:	linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [PATCH] vt: avoid BUG_ON in con_shutdown when con_open returns
 with error

O
> +static inline void con_ops_set_shutdown(void);
>  static int con_open(struct tty_struct *, struct file *);
>  static void vc_init(struct vc_data *vc, unsigned int rows,
>  		    unsigned int cols, int do_clear);
> @@ -2806,6 +2807,14 @@ static int con_open(struct tty_struct *tty,
> struct file *filp) tty->driver_data = vc;
>  			vc->port.tty = tty;
>  
> +			/* We must set shutdown only here, otherwise
> +			 * we returned from con_open with error,
> which
> +			 * will make tty core call tty_release, that
> +			 * in its call path makes con_shutdown being
> +			 * called without tty->driver_data being set,
> +			 * triggering the BUG_ON there */
> +			con_ops_set_shutdown();

No we cannot go around patching the tty_operations - they are not
locked for one.

Probably this is one case where making con_shutdown() check is the
right answer.
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