netdev - [PATCH v2 net-next] sock: relax WARN_ON() in sock_owned_by

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Message-ID: <1461591249.5535.19.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Mon, 25 Apr 2016 06:34:09 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Valdis.Kletnieks@...edu
Cc:	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: [PATCH v2 net-next] sock: relax WARN_ON() in sock_owned_by_user()

From: Eric Dumazet <edumazet@...gle.com>

Valdis reported tons of stack dumps caused by WARN_ON() in
sock_owned_by_user()

This test needs to be relaxed if/when lockdep disables itself.

Note that other lockdep_sock_is_held() callers are all from
rcu_dereference_protected() sections which already are disabled
if/when lockdep has been disabled.

Fixes: fafc4e1ea1a4 ("sock: tigthen lockdep checks for sock_owned_by_user")
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@...edu>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
 include/net/sock.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 52448baf19d7..2fdb87f176cf 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1409,7 +1409,7 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow)
 static inline bool sock_owned_by_user(const struct sock *sk)
 {
 #ifdef CONFIG_LOCKDEP
-	WARN_ON(!lockdep_sock_is_held(sk));
+	WARN_ON_ONCE(!lockdep_sock_is_held(sk) && debug_locks);
 #endif
 	return sk->sk_lock.owned;
 }