From 0c0856714ed742acf40d30b422eba3d7a5e74a91 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Wed, 28 Jun 2023 06:29:42 +0000
Subject: [PATCH] Revert "tcp: deny tcp_disconnect() when threads are waiting"

This reverts commit cccc6209708f59b0d5f0b4853588a720c829a111 which is
commit 4faeee0cf8a5d88d63cdbc3bab124fb0e6aed08c upstream.

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

Bug: 161946584
Change-Id: If50dd244848a8aa70b08be347020b263c71f4a61
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 ad88af26a118..99ef1004bbc6 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -328,7 +328,6 @@ struct bpf_local_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
@@ -413,7 +412,6 @@ struct sock {
 	unsigned int		sk_napi_id;
 #endif
 	int			sk_rcvbuf;
-	int			sk_wait_pending;
 
 	struct sk_filter __rcu	*sk_filter;
 	union {
@@ -1118,7 +1116,6 @@ 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) {						\
@@ -1128,7 +1125,6 @@ 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 038e5915cd38..769902ff9eff 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -588,7 +588,6 @@ 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_*.
@@ -604,7 +603,6 @@ 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 713f77d4df5f..4fbc23e1e640 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -839,7 +839,6 @@ 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 bf237c6cf891..35c9dc0fb701 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2727,12 +2727,6 @@ 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);