From de0a430e6c42877cbe47295e70f9221d6fcd1f65 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Wed, 21 Jun 2023 16:38:28 +0000
Subject: [PATCH] Revert "tcp: deny tcp_disconnect() when threads are waiting"

This reverts commit 32e9a9ee285ff1c72beafca561fb84315365dda3 which is
commit 4faeee0cf8a5d88d63cdbc3bab124fb0e6aed08c upstream.

It breaks the Android kernel abi, and if it is needed can be brought
back in an ABI-safe way.

Bug: 161946584
Change-Id: I228195563c82462203d9aa93d7287d72481204c6
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
---
 include/net/sock.h              | 4 ----
 net/ipv4/af_inet.c              | 2 --
 net/ipv4/inet_connection_sock.c | 1 -
 net/ipv4/tcp.c                  | 6 ------
 4 files changed, 13 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 58700c3d09b0..d8c32969aca5 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -311,7 +311,6 @@ struct bpf_sk_storage;
   *	@sk_cgrp_data: cgroup data for this cgroup
   *	@sk_memcg: this socket's memory cgroup association
   *	@sk_write_pending: a write to stream socket waits to start
-  *	@sk_wait_pending: number of threads blocked on this socket
   *	@sk_state_change: callback to indicate change in the state of the sock
   *	@sk_data_ready: callback to indicate there is data to be processed
   *	@sk_write_space: callback to indicate there is bf sending space available
@@ -393,7 +392,6 @@ struct sock {
 	unsigned int		sk_napi_id;
 #endif
 	int			sk_rcvbuf;
-	int			sk_wait_pending;
 
 	struct sk_filter __rcu	*sk_filter;
 	union {
@@ -1042,7 +1040,6 @@ static inline void sock_rps_reset_rxhash(struct sock *sk)
 
 #define sk_wait_event(__sk, __timeo, __condition, __wait)		\
 	({	int __rc;						\
-		__sk->sk_wait_pending++;				\
 		release_sock(__sk);					\
 		__rc = __condition;					\
 		if (!__rc) {						\
@@ -1052,7 +1049,6 @@ static inline void sock_rps_reset_rxhash(struct sock *sk)
 		}							\
 		sched_annotate_sleep();					\
 		lock_sock(__sk);					\
-		__sk->sk_wait_pending--;				\
 		__rc = __condition;					\
 		__rc;							\
 	})
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 1da57bfb7fb2..ac88429c5895 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -582,7 +582,6 @@ static long inet_wait_for_connect(struct sock *sk, long timeo, int writebias)
 
 	add_wait_queue(sk_sleep(sk), &wait);
 	sk->sk_write_pending += writebias;
-	sk->sk_wait_pending++;
 
 	/* Basic assumption: if someone sets sk->sk_err, he _must_
 	 * change state of the socket from TCP_SYN_*.
@@ -598,7 +597,6 @@ static long inet_wait_for_connect(struct sock *sk, long timeo, int writebias)
 	}
 	remove_wait_queue(sk_sleep(sk), &wait);
 	sk->sk_write_pending -= writebias;
-	sk->sk_wait_pending--;
 	return timeo;
 }
 
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 374a0c3f39cc..04593893e0c6 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -824,7 +824,6 @@ struct sock *inet_csk_clone_lock(const struct sock *sk,
 	if (newsk) {
 		struct inet_connection_sock *newicsk = inet_csk(newsk);
 
-		newsk->sk_wait_pending = 0;
 		inet_sk_set_state(newsk, TCP_SYN_RECV);
 		newicsk->icsk_bind_hash = NULL;
 
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index fdf2ddc4864d..9be4cc90033c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2581,12 +2581,6 @@ int tcp_disconnect(struct sock *sk, int flags)
 	int old_state = sk->sk_state;
 	u32 seq;
 
-	/* Deny disconnect if other threads are blocked in sk_wait_event()
-	 * or inet_wait_for_connect().
-	 */
-	if (sk->sk_wait_pending)
-		return -EBUSY;
-
 	if (old_state != TCP_CLOSE)
 		tcp_set_state(sk, TCP_CLOSE);