[3.13.y-ckt stable] Patch "openvswitch: Silence RCU lockdep checks from flow lookup." has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    openvswitch: Silence RCU lockdep checks from flow lookup.

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt17.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 527c73be7a664db205b27e966d86ad0add492952 Mon Sep 17 00:00:00 2001
From: Jesse Gross <jesse at nicira.com>
Date: Tue, 3 Dec 2013 10:58:53 -0800
Subject: openvswitch: Silence RCU lockdep checks from flow lookup.

commit 663efa3696232300a8ad3a46bb10482fc0b861cf upstream.

Flow lookup can happen either in packet processing context or userspace
context but it was annotated as requiring RCU read lock to be held. This
also allows OVS mutex to be held without causing warnings.

Reported-by: Justin Pettit <jpettit at nicira.com>
Signed-off-by: Jesse Gross <jesse at nicira.com>
Reviewed-by: Thomas Graf <tgraf at redhat.com>
[ kamal: 3.13-stable prereq for:
  4a46b24 openvswitch: Use exact lookup for flow_get and flow_del. ]
Cc: Joseph Salisbury <joseph.salisbury at canonical.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/openvswitch/datapath.c   | 3 +--
 net/openvswitch/datapath.h   | 2 ++
 net/openvswitch/flow_table.c | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 6f5e1dd..f6069c6 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -701,8 +701,7 @@ static int ovs_flow_cmd_fill_info(struct sw_flow *flow, struct datapath *dp,
 	if (start) {
 		const struct sw_flow_actions *sf_acts;

-		sf_acts = rcu_dereference_check(flow->sf_acts,
-						lockdep_ovsl_is_held());
+		sf_acts = rcu_dereference_ovsl(flow->sf_acts);

 		err = ovs_nla_put_actions(sf_acts->actions,
 					  sf_acts->actions_len, skb);
diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index 4067ea4..ba13be4 100644
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -145,6 +145,8 @@ int lockdep_ovsl_is_held(void);
 #define ASSERT_OVSL()		WARN_ON(unlikely(!lockdep_ovsl_is_held()))
 #define ovsl_dereference(p)					\
 	rcu_dereference_protected(p, lockdep_ovsl_is_held())
+#define rcu_dereference_ovsl(p)					\
+	rcu_dereference_check(p, lockdep_ovsl_is_held())

 static inline struct net *ovs_dp_get_net(struct datapath *dp)
 {
diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index e425427..0ddf2bc 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -433,7 +433,7 @@ struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *tbl,
 				    const struct sw_flow_key *key,
 				    u32 *n_mask_hit)
 {
-	struct table_instance *ti = rcu_dereference(tbl->ti);
+	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
 	struct sw_flow_mask *mask;
 	struct sw_flow *flow;

--
1.9.1