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Message-ID: <4DB0FC43.8000800@schaufler-ca.com> Date: Thu, 21 Apr 2011 20:55:47 -0700 From: Casey Schaufler <casey@...aufler-ca.com> To: Andi Kleen <andi@...stfloor.org> CC: Andi Kleen <ak@...ux.intel.com>, jmorris@...ei.org, linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] SMACK: Add missing rcu_read_lock/unlock for process capability walk. On 4/21/2011 8:58 AM, Andi Kleen wrote: > 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? Because the entries can be modified in place. > 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? Yes. > -Andi > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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