From: Andi Kleen <andi@firstfloor.org>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: Andi Kleen <andi@firstfloor.org>, Andi Kleen <ak@linux.intel.com>,
jmorris@namei.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] SMACK: Add missing rcu_read_lock/unlock for process capability walk.
Date: Thu, 21 Apr 2011 17:58:32 +0200 [thread overview]
Message-ID: <20110421155832.GU16484@one.firstfloor.org> (raw)
In-Reply-To: <4DAF7EAC.8010504@schaufler-ca.com>
On Wed, Apr 20, 2011 at 05:47:40PM -0700, Casey Schaufler wrote:
> On 4/20/2011 5:08 PM, Andi Kleen wrote:
> >> The global list, yes. The task specific list, no. Modifying the local
> >> list is like any other modification of the cred structure and requires
> >> the cred be copied.
> > But you still need to free it eventually right? And that freeing will
> > need RCU on the reader.
>
> Entries are never freed from the global list. Someone is working
> on a patch to do that, but is running into - wait for it - locking
> issues.
Then why do you use rcu_read_lock() at all?
You can drop all the rcu_read_lock()s and probably the other *_rcu
list accesses then. And my patch is indeed not needed.
> Entries on the local lists are only freed when the task exits.
You mean the last user of the cred?
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2011-04-21 15:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-20 22:00 [PATCH] SMACK: Add missing rcu_read_lock/unlock for process capability walk Andi Kleen
2011-04-20 22:51 ` Casey Schaufler
2011-04-20 23:18 ` Andi Kleen
2011-04-20 23:43 ` Casey Schaufler
2011-04-21 0:08 ` Andi Kleen
2011-04-21 0:47 ` Casey Schaufler
2011-04-21 15:58 ` Andi Kleen [this message]
2011-04-22 3:55 ` Casey Schaufler
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