Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756738Ab3JIVab (ORCPT ); Wed, 9 Oct 2013 17:30:31 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:48360 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756727Ab3JIVa2 (ORCPT ); Wed, 9 Oct 2013 17:30:28 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, "Paul E. McKenney" , Stephen Hemminger , "David S. Miller" , bridge@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v2 tip/core/rcu 04/13] wireless: Apply rcu_access_pointer() to avoid sparse false positive Date: Wed, 9 Oct 2013 14:29:37 -0700 Message-Id: <1381354186-16285-4-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1381354186-16285-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20131009212920.GA15413@linux.vnet.ibm.com> <1381354186-16285-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13100921-6688-0000-0000-00000263BE30 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3375 Lines: 89 From: "Paul E. McKenney" The sparse checking for rcu_assign_pointer() was recently upgraded to reject non-__kernel address spaces. This also rejects __rcu, which is almost always the right thing to do. However, the uses in cfg80211_combine_bsses() and cfg80211_bss_update() are legitimate: They are assigning a pointer to an element from an RCU-protected list, and all elements of this list are already visible to caller. This commit therefore silences these false positives by laundering the pointers using rcu_access_pointer() as suggested by Josh Triplett. Reported-by: kbuild test robot Signed-off-by: Paul E. McKenney Cc: Stephen Hemminger Cc: "David S. Miller" Cc: bridge@lists.linux-foundation.org Cc: netdev@vger.kernel.org --- net/wireless/scan.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/net/wireless/scan.c b/net/wireless/scan.c index eeb71480f1af..edde117c1863 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -671,7 +671,7 @@ static bool cfg80211_combine_bsses(struct cfg80211_registered_device *dev, bss->pub.hidden_beacon_bss = &new->pub; new->refcount += bss->refcount; rcu_assign_pointer(bss->pub.beacon_ies, - new->pub.beacon_ies); + rcu_access_pointer(new->pub.beacon_ies)); } return true; @@ -706,10 +706,10 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev, old = rcu_access_pointer(found->pub.proberesp_ies); rcu_assign_pointer(found->pub.proberesp_ies, - tmp->pub.proberesp_ies); + rcu_access_pointer(tmp->pub.proberesp_ies)); /* Override possible earlier Beacon frame IEs */ rcu_assign_pointer(found->pub.ies, - tmp->pub.proberesp_ies); + rcu_access_pointer(tmp->pub.proberesp_ies)); if (old) kfree_rcu((struct cfg80211_bss_ies *)old, rcu_head); @@ -740,12 +740,12 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev, old = rcu_access_pointer(found->pub.beacon_ies); rcu_assign_pointer(found->pub.beacon_ies, - tmp->pub.beacon_ies); + rcu_access_pointer(tmp->pub.beacon_ies)); /* Override IEs if they were from a beacon before */ if (old == rcu_access_pointer(found->pub.ies)) rcu_assign_pointer(found->pub.ies, - tmp->pub.beacon_ies); + rcu_access_pointer(tmp->pub.beacon_ies)); /* Assign beacon IEs to all sub entries */ list_for_each_entry(bss, &found->hidden_list, @@ -756,7 +756,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev, WARN_ON(ies != old); rcu_assign_pointer(bss->pub.beacon_ies, - tmp->pub.beacon_ies); + rcu_access_pointer(tmp->pub.beacon_ies)); } if (old) @@ -804,7 +804,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev, &hidden->hidden_list); hidden->refcount++; rcu_assign_pointer(new->pub.beacon_ies, - hidden->pub.beacon_ies); + rcu_access_pointer(hidden->pub.beacon_ies)); } } else { /* -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/