linux-kernel - Re: [PATCH] [2.6.24-rc3-mm1] loop cleanup in fs/namespace.c

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Date:	Mon, 26 Nov 2007 10:30:28 +0000
From:	Al Viro <viro@....linux.org.uk>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Dmitri Vorobiev <dmitri.vorobiev@...il.com>, zach.brown@...cle.com,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [2.6.24-rc3-mm1] loop cleanup in fs/namespace.c - repost

On Wed, Nov 21, 2007 at 03:24:33PM -0800, Andrew Morton wrote:
> -repeat:
> -	if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
> +	while (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
>  		if (likely(!mnt->mnt_pinned)) {
>  			spin_unlock(&vfsmount_lock);
>  			__mntput(mnt);
> -			return;
> +			break;
>  		}
>  		atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
>  		mnt->mnt_pinned = 0;
>  		spin_unlock(&vfsmount_lock);
>  		acct_auto_close_mnt(mnt);
>  		security_sb_umount_close(mnt);
> -		goto repeat;
>  	}
>  }
>  
> This patch has no changelog which I can use.

BTW, I have a problem with that one.  The change is misleading; FWIW,
I'm very tempted to turn that into tail recursion, with

	if (!atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock))
		return;

in the very beginning (i.e. invert the test and pull the body to top level).
-
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