linux-kernel - Re: [PATCH, RFC] fasync() BKL pushdown

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Message-ID: <20080620150535.5efc2ec0@bike.lwn.net>
Date:	Fri, 20 Jun 2008 15:05:35 -0600
From:	Jonathan Corbet <corbet@....net>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Al Viro <viro@...IV.linux.org.uk>
Subject: Re: [PATCH, RFC] fasync() BKL pushdown

On Fri, 20 Jun 2008 13:58:40 -0700
Arjan van de Ven <arjan@...radead.org> wrote:

> only question is if this one is really needed:
> +	lock_kernel();
>  	tty = (struct tty_struct *)filp->private_data;
>  	if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
> "tty_fasync"))
> -		return 0;
> +		goto out;
>  
>  	retval = fasync_helper(fd, filp, on, &tty->fasync);
>  	if (retval <= 0)
> 
> (given that it just calls the helper.. mostly and that Alan has been
> busy removing the BKL from the tty layer)

There's enough other stuff going on there, including manipulations of
the tty_struct, waitqueue_active() checks, etc., that I figured I should
really leave the BKL in there and let Alan figure it out.  I've learned
that it's best to tread with great care in that part of the kernel...

jon


Jonathan Corbet / LWN.net / corbet@....net
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