Subject: [PATCH v2 net-next 2/4] af_unix: Return struct unix_sock from unix_get_socket().

From: Kuniyuki Iwashima <[email-masked]>
Date: Wed, 22 Nov 2023 17:47:45 -0800

Currently, unix_get_socket() returns struct sock, but after calling
it, we always cast it to unix_sk().

Let's return struct unix_sock from unix_get_socket().

Signed-off-by: Kuniyuki Iwashima <[email-masked]>
---
 include/linux/io_uring.h |  4 ++--
 include/net/af_unix.h    |  2 +-
 io_uring/io_uring.c      |  5 +++--
 net/unix/garbage.c       | 19 +++++++------------
 net/unix/scm.c           | 26 +++++++++++---------------
 5 files changed, 24 insertions(+), 32 deletions(-)

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index aefb73eeeebf..be16677f0e4c 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -54,7 +54,7 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 			      struct iov_iter *iter, void *ioucmd);
 void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2,
 			unsigned issue_flags);
-struct sock *io_uring_get_socket(struct file *file);
+struct unix_sock *io_uring_get_socket(struct file *file);
 void __io_uring_cancel(bool cancel_all);
 void __io_uring_free(struct task_struct *tsk);
 void io_uring_unreg_ringfd(void);
@@ -111,7 +111,7 @@ static inline void io_uring_cmd_do_in_task_lazy(struct io_uring_cmd *ioucmd,
 			void (*task_work_cb)(struct io_uring_cmd *, unsigned))
 {
 }
-static inline struct sock *io_uring_get_socket(struct file *file)
+static inline struct unix_sock *io_uring_get_socket(struct file *file)
 {
 	return NULL;
 }
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 5a8a670b1920..c628d30ceb19 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -14,7 +14,7 @@ void unix_destruct_scm(struct sk_buff *skb);
 void io_uring_destruct_scm(struct sk_buff *skb);
 void unix_gc(void);
 void wait_for_unix_gc(void);
-struct sock *unix_get_socket(struct file *filp);
+struct unix_sock *unix_get_socket(struct file *filp);
 struct sock *unix_peer_get(struct sock *sk);
 
 #define UNIX_HASH_MOD	(256 - 1)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ed254076c723..daed897f5975 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -177,13 +177,14 @@ static struct ctl_table kernel_io_uring_disabled_table[] = {
 };
 #endif
 
-struct sock *io_uring_get_socket(struct file *file)
+struct unix_sock *io_uring_get_socket(struct file *file)
 {
 #if defined(CONFIG_UNIX)
 	if (io_is_uring_fops(file)) {
 		struct io_ring_ctx *ctx = file->private_data;
 
-		return ctx->ring_sock->sk;
+		if (ctx->ring_sock->sk)
+			return unix_sk(ctx->ring_sock->sk);
 	}
 #endif
 	return NULL;
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index db1bb99bb793..4d634f5f6a55 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -105,20 +105,15 @@ static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
 
 			while (nfd--) {
 				/* Get the socket the fd matches if it indeed does so */
-				struct sock *sk = unix_get_socket(*fp++);
+				struct unix_sock *u = unix_get_socket(*fp++);
 
-				if (sk) {
-					struct unix_sock *u = unix_sk(sk);
+				/* Ignore non-candidates, they could have been added
+				 * to the queues after starting the garbage collection
+				 */
+				if (u && test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) {
+					hit = true;
 
-					/* Ignore non-candidates, they could
-					 * have been added to the queues after
-					 * starting the garbage collection
-					 */
-					if (test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) {
-						hit = true;
-
-						func(u);
-					}
+					func(u);
 				}
 			}
 			if (hit && hitlist != NULL) {
diff --git a/net/unix/scm.c b/net/unix/scm.c
index 4b3979272a81..36ce8fed9acc 100644
--- a/net/unix/scm.c
+++ b/net/unix/scm.c
@@ -21,9 +21,8 @@ EXPORT_SYMBOL(gc_inflight_list);
 DEFINE_SPINLOCK(unix_gc_lock);
 EXPORT_SYMBOL(unix_gc_lock);
 
-struct sock *unix_get_socket(struct file *filp)
+struct unix_sock *unix_get_socket(struct file *filp)
 {
-	struct sock *u_sock = NULL;
 	struct inode *inode = file_inode(filp);
 
 	/* Socket ? */
@@ -34,12 +33,13 @@ struct sock *unix_get_socket(struct file *filp)
 
 		/* PF_UNIX ? */
 		if (s && ops && ops->family == PF_UNIX)
-			u_sock = s;
-	} else {
-		/* Could be an io_uring instance */
-		u_sock = io_uring_get_socket(filp);
+			return unix_sk(s);
+
+		return NULL;
 	}
-	return u_sock;
+
+	/* Could be an io_uring instance */
+	return io_uring_get_socket(filp);
 }
 EXPORT_SYMBOL(unix_get_socket);
 
@@ -48,13 +48,11 @@ EXPORT_SYMBOL(unix_get_socket);
  */
 void unix_inflight(struct user_struct *user, struct file *fp)
 {
-	struct sock *s = unix_get_socket(fp);
+	struct unix_sock *u = unix_get_socket(fp);
 
 	spin_lock(&unix_gc_lock);
 
-	if (s) {
-		struct unix_sock *u = unix_sk(s);
-
+	if (u) {
 		if (!u->inflight) {
 			BUG_ON(!list_empty(&u->link));
 			list_add_tail(&u->link, &gc_inflight_list);
@@ -71,13 +69,11 @@ void unix_inflight(struct user_struct *user, struct file *fp)
 
 void unix_notinflight(struct user_struct *user, struct file *fp)
 {
-	struct sock *s = unix_get_socket(fp);
+	struct unix_sock *u = unix_get_socket(fp);
 
 	spin_lock(&unix_gc_lock);
 
-	if (s) {
-		struct unix_sock *u = unix_sk(s);
-
+	if (u) {
 		BUG_ON(!u->inflight);
 		BUG_ON(list_empty(&u->link));
 
-- 
2.30.2