From ce75ac8da42385c77b052fb10ea63f34fc328253 Mon Sep 17 00:00:00 2001
From: Michael Bestas <mkbestas@lineageos.org>
Date: Wed, 19 Mar 2025 07:33:15 +0200
Subject: [PATCH] Revert "af_unix: Do not use atomic ops for
 unix_sk(sk)->inflight."

This reverts commit 9ef7c24511b39a841fae4fa064349dddb9214c83.

Reason for revert: Conflicts with upstream commits.

Change-Id: Id7ec5e6a24fd6702a7525893b6e3b3f2428b4704
---
 include/net/af_unix.h |  2 +-
 net/unix/af_unix.c    |  4 ++--
 net/unix/garbage.c    | 17 +++++++++--------
 net/unix/scm.c        |  8 +++-----
 4 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 1b3c59323002..3426d6dacc45 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -58,7 +58,7 @@ struct unix_sock {
 	struct mutex		iolock, bindlock;
 	struct sock		*peer;
 	struct list_head	link;
-	unsigned long		inflight;
+	atomic_long_t		inflight;
 	spinlock_t		lock;
 	unsigned long		gc_flags;
 #define UNIX_GC_CANDIDATE	0
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 966856dbea88..304eb26b34dc 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -809,11 +809,11 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
 	sk->sk_write_space	= unix_write_space;
 	sk->sk_max_ack_backlog	= net->unx.sysctl_max_dgram_qlen;
 	sk->sk_destruct		= unix_sock_destructor;
-	u = unix_sk(sk);
-	u->inflight = 0;
+	u	  = unix_sk(sk);
 	u->path.dentry = NULL;
 	u->path.mnt = NULL;
 	spin_lock_init(&u->lock);
+	atomic_long_set(&u->inflight, 0);
 	INIT_LIST_HEAD(&u->link);
 	mutex_init(&u->iolock); /* single task reading lock */
 	mutex_init(&u->bindlock); /* single task binding lock */
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 312474c23e9a..dc2763540393 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -166,18 +166,17 @@ static void scan_children(struct sock *x, void (*func)(struct unix_sock *),
 
 static void dec_inflight(struct unix_sock *usk)
 {
-	usk->inflight--;
+	atomic_long_dec(&usk->inflight);
 }
 
 static void inc_inflight(struct unix_sock *usk)
 {
-	usk->inflight++;
+	atomic_long_inc(&usk->inflight);
 }
 
 static void inc_inflight_move_tail(struct unix_sock *u)
 {
-	u->inflight++;
-
+	atomic_long_inc(&u->inflight);
 	/* If this still might be part of a cycle, move it to the end
 	 * of the list, so that it's checked even if it was already
 	 * passed over
@@ -238,12 +237,14 @@ void unix_gc(void)
 	 */
 	list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
 		long total_refs;
+		long inflight_refs;
 
 		total_refs = file_count(u->sk.sk_socket->file);
+		inflight_refs = atomic_long_read(&u->inflight);
 
-		BUG_ON(!u->inflight);
-		BUG_ON(total_refs < u->inflight);
-		if (total_refs == u->inflight) {
+		BUG_ON(inflight_refs < 1);
+		BUG_ON(total_refs < inflight_refs);
+		if (total_refs == inflight_refs) {
 			list_move_tail(&u->link, &gc_candidates);
 			__set_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
 			__set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
@@ -270,7 +271,7 @@ void unix_gc(void)
 		/* Move cursor to after the current position. */
 		list_move(&cursor, &u->link);
 
-		if (u->inflight) {
+		if (atomic_long_read(&u->inflight) > 0) {
 			list_move_tail(&u->link, &not_cycle_list);
 			__clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
 			scan_children(&u->sk, inc_inflight_move_tail, NULL);
diff --git a/net/unix/scm.c b/net/unix/scm.c
index ab2d664b7528..e881a6e78af5 100644
--- a/net/unix/scm.c
+++ b/net/unix/scm.c
@@ -53,13 +53,12 @@ void unix_inflight(struct user_struct *user, struct file *fp)
 	if (s) {
 		struct unix_sock *u = unix_sk(s);
 
-		if (!u->inflight) {
+		if (atomic_long_inc_return(&u->inflight) == 1) {
 			BUG_ON(!list_empty(&u->link));
 			list_add_tail(&u->link, &gc_inflight_list);
 		} else {
 			BUG_ON(list_empty(&u->link));
 		}
-		u->inflight++;
 		/* Paired with READ_ONCE() in wait_for_unix_gc() */
 		WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1);
 	}
@@ -76,11 +75,10 @@ void unix_notinflight(struct user_struct *user, struct file *fp)
 	if (s) {
 		struct unix_sock *u = unix_sk(s);
 
-		BUG_ON(!u->inflight);
+		BUG_ON(!atomic_long_read(&u->inflight));
 		BUG_ON(list_empty(&u->link));
 
-		u->inflight--;
-		if (!u->inflight)
+		if (atomic_long_dec_and_test(&u->inflight))
 			list_del_init(&u->link);
 		/* Paired with READ_ONCE() in wait_for_unix_gc() */
 		WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1);