linux-kernel - Re: [PATCH] de-semaphorize smackfs

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Message-Id: <1205854899.10894.134.camel@localhost.localdomain>
Date:	Tue, 18 Mar 2008 08:41:39 -0700
From:	Daniel Walker <dwalker@...sta.com>
To:	Jonathan Corbet <corbet@....net>
Cc:	linux-kernel@...r.kernel.org,
	Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH] de-semaphorize smackfs


On Mon, 2008-03-17 at 17:14 -0600, Jonathan Corbet wrote:

> @@ -171,7 +171,7 @@ static int smk_open_load(struct inode *inode, struct file *file)
>  	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
>  		return seq_open(file, &load_seq_ops);
>  
> -	if (down_interruptible(&smack_write_sem))
> +	if (mutex_lock_interruptible(&smack_write_mutex))
>  		return -ERESTARTSYS;
>  
>  	return 0;

There's a disconnect between the lock unlock calls, when the locking
application returns to userspace. Mutex's have a restriction that you
can't return to userspace while holding the lock.

Daniel

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