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Message-Id: <1457391064-6660-233-git-send-email-kamal@canonical.com>
Date: Mon, 7 Mar 2016 14:50:23 -0800
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: Eric Dumazet <edumazet@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 232/273] ipv6: fix a lockdep splat
4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Eric Dumazet <edumazet@...gle.com>
[ Upstream commit 44c3d0c1c0a880354e9de5d94175742e2c7c9683 ]
Silence lockdep false positive about rcu_dereference() being
used in the wrong context.
First one should use rcu_dereference_protected() as we own the spinlock.
Second one should be a normal assignation, as no barrier is needed.
Fixes: 18367681a10bd ("ipv6 flowlabel: Convert np->ipv6_fl_list to RCU.")
Reported-by: Dave Jones <davej@...emonkey.org.uk>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
net/ipv6/ip6_flowlabel.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index 1f9ebe3..dc2db4f 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -540,12 +540,13 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
}
spin_lock_bh(&ip6_sk_fl_lock);
for (sflp = &np->ipv6_fl_list;
- (sfl = rcu_dereference(*sflp)) != NULL;
+ (sfl = rcu_dereference_protected(*sflp,
+ lockdep_is_held(&ip6_sk_fl_lock))) != NULL;
sflp = &sfl->next) {
if (sfl->fl->label == freq.flr_label) {
if (freq.flr_label == (np->flow_label&IPV6_FLOWLABEL_MASK))
np->flow_label &= ~IPV6_FLOWLABEL_MASK;
- *sflp = rcu_dereference(sfl->next);
+ *sflp = sfl->next;
spin_unlock_bh(&ip6_sk_fl_lock);
fl_release(sfl->fl);
kfree_rcu(sfl, rcu);
--
2.7.0
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