Return-path: Received: from mail-vb0-f46.google.com ([209.85.212.46]:63880 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757577Ab2EDOgA convert rfc822-to-8bit (ORCPT ); Fri, 4 May 2012 10:36:00 -0400 Received: by vbbff1 with SMTP id ff1so2065969vbb.19 for ; Fri, 04 May 2012 07:35:59 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4FA3DD87.7030004@lwfinger.net> References: <4F83A6DE.7070109@lwfinger.net> <1334201497.3788.1.camel@jlt3.sipsolutions.net> <4F865155.2000202@lwfinger.net> <1334202842.3788.10.camel@jlt3.sipsolutions.net> <4F86FA05.5080404@lwfinger.net> <1334246145.4062.0.camel@jlt3.sipsolutions.net> <4FA0371E.9040704@lwfinger.net> <20120502100012.GA8492@arm.com> <1335978471.4295.3.camel@jlt3.sipsolutions.net> <20120502200955.GI2450@linux.vnet.ibm.com> <1336070304.5167.4.camel@jlt3.sipsolutions.net> <4FA37461.6050304@lwfinger.net> <4FA3DD87.7030004@lwfinger.net> Date: Fri, 4 May 2012 20:05:59 +0530 Message-ID: (sfid-20120504_163604_862166_C5A1DCA9) Subject: Re: Suspicious RCU usage in mac80211 From: Mohammed Shafi To: Larry Finger Cc: Johannes Berg , Catalin Marinas , wireless Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, May 4, 2012 at 7:15 PM, Larry Finger wrote: > On 05/04/2012 01:48 AM, Mohammed Shafi wrote: >> >> On Fri, May 4, 2012 at 12:10 PM, Mohammed Shafi >> ?wrote: >>> >>> Hi Larry, >>> >>> On Fri, May 4, 2012 at 11:47 AM, Larry Finger >>> ?wrote: >>>> >>>> On 05/03/2012 01:38 PM, Johannes Berg wrote: >>>>> >>>>> >>>>> diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c >>>>> index 5b7053c..40d3ff4 100644 >>>>> --- a/net/mac80211/agg-tx.c >>>>> +++ b/net/mac80211/agg-tx.c >>>>> @@ -421,16 +421,22 @@ static void >>>>> sta_tx_agg_session_timer_expired(unsigned long data) >>>>> ? ? ? ?struct tid_ampdu_tx *tid_tx; >>>>> ? ? ? ?unsigned long timeout; >>>>> >>>>> - ? ? ? tid_tx = rcu_dereference_protected_tid_tx(sta, *ptid); >>>>> - ? ? ? if (!tid_tx) >>>>> + ? ? ? rcu_read_lock(); >>>>> + ? ? ? tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[*ptid]); >> >> >> Larry, Johannes seems to use rcu_dereference straight way just like in >> 'sta_addba_resp_timer_expired' >> and have it protected by rcu_read_locks > > > Sorry. I missed that subtle difference. Submitted "from Johannes". no problem thanks! yeah but it seems my gmail seems to be identify those changes!! -- thanks, shafi