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

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Date:	Fri, 20 Jun 2008 13:58:40 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Jonathan Corbet <corbet@....net>
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 11:29:14 -0600
Jonathan Corbet <corbet@....net> wrote:
> 
> The majority of fasync() functions just call fasync_helper() with a
> pointer to an fasync_struct reachable from the file structure.  Given
> that (1) the struct file will not go away while fasync() is running,
> and (2) the VFS-level fasync() stuff is protected with the Big Fasync
> Lock, I contend that these simple implementations have no need for
> the BKL.  Once those are filtered out, there's really only a
> half-dozen places which need to be fixed.


> Jonathan Corbet (7):
>       mpt: fasync BKL pushdown
>       i2o: fasync BKL pushdown
>       tun: fasync BKL pushdown
>       tty_io: fasync BKL pushdown
>       Bluetooth VHCI: fasync BKL pushdown
>       ecryptfs: fasync BKL pushdown
>       Call fasync() functions without the BKL
> 
> And the actual patch is appended.  If nobody objects, I'll pull these
> into the bkl-removal tree shortly.
> 

looks good to me

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)


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