af_unix: Remove io_uring code for GC.

Since commit 705318a99a13 ("io_uring/af_unix: disable sending
io_uring over sockets"), io_uring's unix socket cannot be passed
via SCM_RIGHTS, so it does not contribute to cyclic reference and
no longer be candidate for garbage collection.

Also, commit 6e5e6d274956 ("io_uring: drop any code related to
SCM_RIGHTS") cleaned up SCM_RIGHTS code in io_uring.

Let's do it in AF_UNIX as well by reverting commit 0091bfc81741
("io_uring/af_unix: defer registered files gc to io_uring release")
and commit 10369080454d ("net: reclaim skb->scm_io_uring bit").

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20240129190435.57228-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index f045bbd..9e39b2e 100644 (file)
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -20,7 +20,6 @@ static inline struct unix_sock *unix_get_socket(struct file *filp)
 void unix_inflight(struct user_struct *user, struct file *fp);
 void unix_notinflight(struct user_struct *user, struct file *fp);
 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(struct scm_fp_list *fpl);
 struct sock *unix_peer_get(struct sock *sk);

diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index af676bb..ce5b5f8 100644 (file)
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -184,12 +184,10 @@ static bool gc_in_progress;
 
 static void __unix_gc(struct work_struct *work)
 {
-       struct sk_buff *next_skb, *skb;
-       struct unix_sock *u;
-       struct unix_sock *next;
        struct sk_buff_head hitlist;
-       struct list_head cursor;
+       struct unix_sock *u, *next;
        LIST_HEAD(not_cycle_list);
+       struct list_head cursor;
 
        spin_lock(&unix_gc_lock);
 
@@ -269,30 +267,11 @@ static void __unix_gc(struct work_struct *work)
 
        spin_unlock(&unix_gc_lock);
 
-       /* We need io_uring to clean its registered files, ignore all io_uring
-        * originated skbs. It's fine as io_uring doesn't keep references to
-        * other io_uring instances and so killing all other files in the cycle
-        * will put all io_uring references forcing it to go through normal
-        * release.path eventually putting registered files.
-        */
-       skb_queue_walk_safe(&hitlist, skb, next_skb) {
-               if (skb->destructor == io_uring_destruct_scm) {
-                       __skb_unlink(skb, &hitlist);
-                       skb_queue_tail(&skb->sk->sk_receive_queue, skb);
-               }
-       }
-
        /* Here we are. Hitlist is filled. Die. */
        __skb_queue_purge(&hitlist);
 
        spin_lock(&unix_gc_lock);
 
-       /* There could be io_uring registered files, just push them back to
-        * the inflight list
-        */
-       list_for_each_entry_safe(u, next, &gc_candidates, link)
-               list_move_tail(&u->link, &gc_inflight_list);
-
        /* All candidates should have been detached by now. */
        WARN_ON_ONCE(!list_empty(&gc_candidates));
 

diff --git a/net/unix/scm.c b/net/unix/scm.c
index 505e56c..db65b0a 100644 (file)
--- a/net/unix/scm.c
+++ b/net/unix/scm.c
@@ -148,9 +148,3 @@ void unix_destruct_scm(struct sk_buff *skb)
        sock_wfree(skb);
 }
 EXPORT_SYMBOL(unix_destruct_scm);
-
-void io_uring_destruct_scm(struct sk_buff *skb)
-{
-       unix_destruct_scm(skb);
-}
-EXPORT_SYMBOL(io_uring_destruct_scm);