netdev - [PATCH net-next 4/7] net/ipv6: Move rcu locking to callers of fib6_get_cookie

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Date:   Fri, 20 Apr 2018 15:38:00 -0700
From:   David Ahern <dsahern@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, idosch@...sch.org, roopa@...ulusnetworks.com,
        eric.dumazet@...il.com, weiwan@...gle.com, kafai@...com,
        yoshfuji@...ux-ipv6.org, David Ahern <dsahern@...il.com>
Subject: [PATCH net-next 4/7] net/ipv6: Move rcu locking to callers of fib6_get_cookie_safe

A later patch protects 'from' in rt6_info and this simplifies the
locking needed by it.

Signed-off-by: David Ahern <dsahern@...il.com>
---
 include/net/ip6_fib.h |  6 ++++--
 net/ipv6/route.c      | 13 ++++++++++---
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index dd1481ed8bdb..dc3505fb62b3 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -234,7 +234,6 @@ static inline bool fib6_get_cookie_safe(const struct fib6_info *f6i,
 	struct fib6_node *fn;
 	bool status = false;
 
-	rcu_read_lock();
 	fn = rcu_dereference(f6i->fib6_node);
 
 	if (fn) {
@@ -244,7 +243,6 @@ static inline bool fib6_get_cookie_safe(const struct fib6_info *f6i,
 		status = true;
 	}
 
-	rcu_read_unlock();
 	return status;
 }
 
@@ -252,10 +250,14 @@ static inline u32 rt6_get_cookie(const struct rt6_info *rt)
 {
 	u32 cookie = 0;
 
+	rcu_read_lock();
+
 	if (rt->rt6i_flags & RTF_PCPU ||
 	    (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
 		fib6_get_cookie_safe(rt->from, &cookie);
 
+	rcu_read_unlock();
+
 	return cookie;
 }
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index f8b22183b7fd..810a37ac043b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2159,9 +2159,12 @@ static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie)
 
 static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 {
+	struct dst_entry *dst_ret;
 	struct rt6_info *rt;
 
-	rt = (struct rt6_info *) dst;
+	rt = container_of(dst, struct rt6_info, dst);
+
+	rcu_read_lock();
 
 	/* All IPV6 dsts are created with ->obsolete set to the value
 	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
@@ -2170,9 +2173,13 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 
 	if (rt->rt6i_flags & RTF_PCPU ||
 	    (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
-		return rt6_dst_from_check(rt, cookie);
+		dst_ret = rt6_dst_from_check(rt, cookie);
 	else
-		return rt6_check(rt, cookie);
+		dst_ret = rt6_check(rt, cookie);
+
+	rcu_read_unlock();
+
+	return dst_ret;
 }
 
 static struct dst_entry *ip6_negative_advice(struct dst_entry *dst)
-- 
2.11.0