[3.16.y-ckt stable] Patch "ipv6: fix a lockdep splat" has been added to the 3.16.y-ckt tree
Luis Henriques
luis.henriques at canonical.com
Thu Feb 25 18:34:51 UTC 2016
This is a note to let you know that I have just added a patch titled
ipv6: fix a lockdep splat
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt25.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
---8<------------------------------------------------------------
>From f98a2f91e4b108758615b8321cdf9056d712e1c1 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet at google.com>
Date: Tue, 2 Feb 2016 17:55:01 -0800
Subject: ipv6: fix a lockdep splat
commit 44c3d0c1c0a880354e9de5d94175742e2c7c9683 upstream.
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 at codemonkey.org.uk>
Signed-off-by: Eric Dumazet <edumazet at google.com>
Acked-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.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 4052694c6f2c..f40ba684d69b 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -542,12 +542,13 @@ 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);
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