netdev - [PATCH net-next v2] net: add annotation for sock_{lock,unlock}

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Message-Id: <6ed7ae627d8271fb7f20e0a9c6750fbba1ac2635.1605634911.git.pabeni@redhat.com>
Date:   Tue, 17 Nov 2020 19:43:49 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        linux-sparse@...r.kernel.org
Subject: [PATCH net-next v2] net: add annotation for sock_{lock,unlock}_fast

The static checker is fooled by the non-static locking scheme
implemented by the mentioned helpers.
Let's make its life easier adding some unconditional annotation
so that the helpers are now interpreted as a plain spinlock from
sparse.

v1 -> v2:
 - add __releases() annotation to unlock_sock_fast()

Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
 include/net/sock.h | 10 +++++++---
 net/core/sock.c    |  3 ++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 1d29aeae74fd..093b51719c69 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1595,7 +1595,8 @@ void release_sock(struct sock *sk);
 				SINGLE_DEPTH_NESTING)
 #define bh_unlock_sock(__sk)	spin_unlock(&((__sk)->sk_lock.slock))
 
-bool lock_sock_fast(struct sock *sk);
+bool lock_sock_fast(struct sock *sk) __acquires(&sk->sk_lock.slock);
+
 /**
  * unlock_sock_fast - complement of lock_sock_fast
  * @sk: socket
@@ -1605,11 +1606,14 @@ bool lock_sock_fast(struct sock *sk);
  * If slow mode is on, we call regular release_sock()
  */
 static inline void unlock_sock_fast(struct sock *sk, bool slow)
+	__releases(&sk->sk_lock.slock)
 {
-	if (slow)
+	if (slow) {
 		release_sock(sk);
-	else
+		__release(&sk->sk_lock.slock);
+	} else {
 		spin_unlock_bh(&sk->sk_lock.slock);
+	}
 }
 
 /* Used by processes to "lock" a socket state, so that
diff --git a/net/core/sock.c b/net/core/sock.c
index 727ea1cc633c..9badbe7bb4e4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3078,7 +3078,7 @@ EXPORT_SYMBOL(release_sock);
  *
  *   sk_lock.slock unlocked, owned = 1, BH enabled
  */
-bool lock_sock_fast(struct sock *sk)
+bool lock_sock_fast(struct sock *sk) __acquires(&sk->sk_lock.slock)
 {
 	might_sleep();
 	spin_lock_bh(&sk->sk_lock.slock);
@@ -3096,6 +3096,7 @@ bool lock_sock_fast(struct sock *sk)
 	 * The sk_lock has mutex_lock() semantics here:
 	 */
 	mutex_acquire(&sk->sk_lock.dep_map, 0, 0, _RET_IP_);
+	__acquire(&sk->sk_lock.slock);
 	local_bh_enable();
 	return true;
 }
-- 
2.26.2