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Date: Tue, 24 Sep 2013 18:35:13 -0700 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: linux-kernel@...r.kernel.org Cc: mingo@...nel.org, laijs@...fujitsu.com, dipankar@...ibm.com, akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com, josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com, darren@...art.com, fweisbec@...il.com, sbw@....edu, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, "John W. Linville" <linville@...driver.com>, Johannes Berg <johannes@...solutions.net>, "David S. Miller" <davem@...emloft.net>, linux-wireless@...r.kernel.org, netdev@...r.kernel.org Subject: [PATCH tip/core/rcu 10/13] mac80211: Apply rcu_access_pointer() to avoid sparse false positive From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> 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 sta_info_hash_del() are legitimate: They is 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 this false positive by laundering the pointer using rcu_access_pointer() as suggested by Josh Triplett. Reported-by: kbuild test robot <fengguang.wu@...el.com> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> Cc: "John W. Linville" <linville@...driver.com> Cc: Johannes Berg <johannes@...solutions.net> Cc: "David S. Miller" <davem@...emloft.net> Cc: linux-wireless@...r.kernel.org Cc: netdev@...r.kernel.org --- net/mac80211/sta_info.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index aeb967a..d18ab89 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -75,7 +75,7 @@ static int sta_info_hash_del(struct ieee80211_local *local, return -ENOENT; if (s == sta) { rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], - s->hnext); + rcu_access_pointer(s->hnext)); return 0; } @@ -84,7 +84,7 @@ static int sta_info_hash_del(struct ieee80211_local *local, s = rcu_dereference_protected(s->hnext, lockdep_is_held(&local->sta_mtx)); if (rcu_access_pointer(s->hnext)) { - rcu_assign_pointer(s->hnext, sta->hnext); + rcu_assign_pointer(s->hnext, rcu_access_pointer(sta->hnext)); return 0; } -- 1.8.1.5 -- 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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