[PATCH v2 tip/core/rcu 04/13] wireless: Apply rcu_access_pointer() to avoid sparse false positive
From: Paul E. McKenney <hidden>
Date: 2013-10-09 21:30:31
Also in:
bridge, lkml
Subsystem:
802.11 (including cfg80211/nl80211), the rest · Maintainers:
Johannes Berg, Linus Torvalds
From: "Paul E. McKenney" <redacted> 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 <redacted> Signed-off-by: Paul E. McKenney <redacted> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: "David S. Miller" <davem@davemloft.net> 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