From: Christoph Hellwig <hch@lst.de>
Date: Mon, 30 Jul 2018 09:45:07 +0200
Subject: net: remove bogus RCU annotations on socket.wq
Patch-mainline: v4.19-rc1
Git-commit: e6476c21447c4b17c47e476aade6facf050f31e8
References: bsc#1109837

We never use RCU protection for it, just a lot of cargo-cult
rcu_deference_protects calls.

Note that we do keep the kfree_rcu call for it, as the references through
struct sock are RCU protected and thus might require a grace period before
freeing.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/net.h |    2 +-
 include/net/sock.h  |    2 +-
 net/socket.c        |   10 ++++------
 3 files changed, 6 insertions(+), 8 deletions(-)

--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -117,7 +117,7 @@ struct socket {
 
 	unsigned long		flags;
 
-	struct socket_wq __rcu	*wq;
+	struct socket_wq	*wq;
 
 	struct file		*file;
 	struct sock		*sk;
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1771,7 +1771,7 @@ static inline void sock_orphan(struct so
 static inline void sock_graft(struct sock *sk, struct socket *parent)
 {
 	write_lock_bh(&sk->sk_callback_lock);
-	sk->sk_wq = parent->wq;
+	rcu_assign_pointer(sk->sk_wq, parent->wq);
 	parent->sk = sk;
 	sk_set_socket(sk, parent);
 	sk->sk_uid = SOCK_INODE(parent)->i_uid;
--- a/net/socket.c
+++ b/net/socket.c
@@ -258,7 +258,7 @@ static struct inode *sock_alloc_inode(st
 	init_waitqueue_head(&wq->wait);
 	wq->fasync_list = NULL;
 	wq->flags = 0;
-	RCU_INIT_POINTER(ei->socket.wq, wq);
+	ei->socket.wq = wq;
 
 	ei->socket.state = SS_UNCONNECTED;
 	ei->socket.flags = 0;
@@ -272,11 +272,9 @@ static struct inode *sock_alloc_inode(st
 static void sock_destroy_inode(struct inode *inode)
 {
 	struct socket_alloc *ei;
-	struct socket_wq *wq;
 
 	ei = container_of(inode, struct socket_alloc, vfs_inode);
-	wq = rcu_dereference_protected(ei->socket.wq, 1);
-	kfree_rcu(wq, rcu);
+	kfree_rcu(ei->socket.wq, rcu);
 	kmem_cache_free(sock_inode_cachep, ei);
 }
 
@@ -606,7 +604,7 @@ static void __sock_release(struct socket
 		module_put(owner);
 	}
 
-	if (rcu_dereference_protected(sock->wq, 1)->fasync_list)
+	if (sock->wq->fasync_list)
 		pr_err("%s: fasync list not empty!\n", __func__);
 
 	this_cpu_sub(sockets_in_use, 1);
@@ -1160,7 +1158,7 @@ static int sock_fasync(int fd, struct fi
 		return -EINVAL;
 
 	lock_sock(sk);
-	wq = rcu_dereference_protected(sock->wq, lockdep_sock_is_held(sk));
+	wq = sock->wq;
 	fasync_helper(fd, filp, on, &wq->fasync_list);
 
 	if (!wq->fasync_list)