From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for inode
 information cache
Date: Wed, 20 Oct 2010 10:17:47 +1100
Message-ID: <20101019231747.GC12506@dastard>
References: <20101019225813.12396.2564.stgit@paris.rdu.redhat.com>
 <20101019225839.12396.92630.stgit@paris.rdu.redhat.com>
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To: Eric Paris <eparis@redhat.com>
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On Tue, Oct 19, 2010 at 06:58:39PM -0400, Eric Paris wrote:
> @@ -36,12 +63,11 @@ struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
>  	struct ima_iint_cache *iint;
>  
>  	rcu_read_lock();
> -	iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
> -	if (!iint)
> -		goto out;
> -	kref_get(&iint->refcount);
> -out:
> +	iint = __ima_iint_find(inode);
> +	if (iint)
> +		kref_get(&iint->refcount);
>  	rcu_read_unlock();
> +

This is wrong - the rbtree is protected only by the ima_iint_lock(),
not RCU. Hence you can't do lockless lookups on an rbtree in this
manner as they will race with inserts and deletes.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com