net: Add checking to rcu_dereference() primitives

Update rcu_dereference() primitives to use new lockdep-based
checking. The rcu_dereference() in __in6_dev_get() may be
protected either by rcu_read_lock() or RTNL, per Eric Dumazet.
The rcu_dereference() in __sk_free() is protected by the fact
that it is never reached if an update could change it.  Check
for this by using rcu_dereference_check() to verify that the
struct sock's ->sk_wmem_alloc counter is zero.

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-5-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/core/sock.c b/net/core/sock.c
index e1f6f225f012..305cba401ae6 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1073,7 +1073,8 @@ static void __sk_free(struct sock *sk)
         if (sk->sk_destruct)
                 sk->sk_destruct(sk);
 
-        filter = rcu_dereference(sk->sk_filter);
+        filter = rcu_dereference_check(sk->sk_filter,
+                                       atomic_read(&sk->sk_wmem_alloc) == 0);
         if (filter) {
                 sk_filter_uncharge(sk, filter);
                 rcu_assign_pointer(sk->sk_filter, NULL);