Merge tag 'io_uring-6.5-2023-07-03' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:
 "The fix for the msghdr->msg_inq assigned value being wrong, using -1
  instead of -1U for the signed type.

  Also a fix for ensuring when we're trying to run task_work on an
  exiting task, that we wait for it. This is not really a correctness
  thing as the work is being canceled, but it does help with ensuring
  file descriptors are closed when the task has exited."

* tag 'io_uring-6.5-2023-07-03' of git://git.kernel.dk/linux:
  io_uring: flush offloaded and delayed task_work on exit
  io_uring: remove io_fallback_tw() forward declaration
  io_uring/net: use proper value for msg_inq

Author: torvalds

io_uring/io_uring.c

@@ -149,7 +149,6 @@ static bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
 static void io_queue_sqe(struct io_kiocb *req);
 static void io_move_task_work_from_local(struct io_ring_ctx *ctx);
 static void __io_submit_flush_completions(struct io_ring_ctx *ctx);
-static __cold void io_fallback_tw(struct io_uring_task *tctx);
 
 struct kmem_cache *req_cachep;
 
@@ -1238,6 +1237,34 @@ static inline struct llist_node *io_llist_cmpxchg(struct llist_head *head,
 	return cmpxchg(&head->first, old, new);
 }
 
+static __cold void io_fallback_tw(struct io_uring_task *tctx, bool sync)
+{
+	struct llist_node *node = llist_del_all(&tctx->task_list);
+	struct io_ring_ctx *last_ctx = NULL;
+	struct io_kiocb *req;
+
+	while (node) {
+		req = container_of(node, struct io_kiocb, io_task_work.node);
+		node = node->next;
+		if (sync && last_ctx != req->ctx) {
+			if (last_ctx) {
+				flush_delayed_work(&last_ctx->fallback_work);
+				percpu_ref_put(&last_ctx->refs);
+			}
+			last_ctx = req->ctx;
+			percpu_ref_get(&last_ctx->refs);
+		}
+		if (llist_add(&req->io_task_work.node,
+			      &req->ctx->fallback_llist))
+			schedule_delayed_work(&req->ctx->fallback_work, 1);
+	}
+
+	if (last_ctx) {
+		flush_delayed_work(&last_ctx->fallback_work);
+		percpu_ref_put(&last_ctx->refs);
+	}
+}
+
 void tctx_task_work(struct callback_head *cb)
 {
 	struct io_tw_state ts = {};
@@ -1250,7 +1277,7 @@ void tctx_task_work(struct callback_head *cb)
 	unsigned int count = 0;
 
 	if (unlikely(current->flags & PF_EXITING)) {
-		io_fallback_tw(tctx);
+		io_fallback_tw(tctx, true);
 		return;
 	}
 
@@ -1279,20 +1306,6 @@ void tctx_task_work(struct callback_head *cb)
 	trace_io_uring_task_work_run(tctx, count, loops);
 }
 
-static __cold void io_fallback_tw(struct io_uring_task *tctx)
-{
-	struct llist_node *node = llist_del_all(&tctx->task_list);
-	struct io_kiocb *req;
-
-	while (node) {
-		req = container_of(node, struct io_kiocb, io_task_work.node);
-		node = node->next;
-		if (llist_add(&req->io_task_work.node,
-			      &req->ctx->fallback_llist))
-			schedule_delayed_work(&req->ctx->fallback_work, 1);
-	}
-}
-
 static inline void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
 {
 	struct io_ring_ctx *ctx = req->ctx;
@@ -1359,7 +1372,7 @@ static void io_req_normal_work_add(struct io_kiocb *req)
 	if (likely(!task_work_add(req->task, &tctx->task_work, ctx->notify_method)))
 		return;
 
-	io_fallback_tw(tctx);
+	io_fallback_tw(tctx, false);
 }
 
 void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
@@ -3109,6 +3122,8 @@ static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 	if (ctx->rings)
 		io_kill_timeouts(ctx, NULL, true);
 
+	flush_delayed_work(&ctx->fallback_work);
+
 	INIT_WORK(&ctx->exit_work, io_ring_exit_work);
 	/*
 	 * Use system_unbound_wq to avoid spawning tons of event kworkers

io_uring/net.c

@@ -631,7 +631,7 @@ static inline bool io_recv_finish(struct io_kiocb *req, int *ret,
 	unsigned int cflags;
 
 	cflags = io_put_kbuf(req, issue_flags);
-	if (msg->msg_inq && msg->msg_inq != -1U)
+	if (msg->msg_inq && msg->msg_inq != -1)
 		cflags |= IORING_CQE_F_SOCK_NONEMPTY;
 
 	if (!(req->flags & REQ_F_APOLL_MULTISHOT)) {
@@ -646,7 +646,7 @@ static inline bool io_recv_finish(struct io_kiocb *req, int *ret,
 			io_recv_prep_retry(req);
 			/* Known not-empty or unknown state, retry */
 			if (cflags & IORING_CQE_F_SOCK_NONEMPTY ||
-			    msg->msg_inq == -1U)
+			    msg->msg_inq == -1)
 				return false;
 			if (issue_flags & IO_URING_F_MULTISHOT)
 				*ret = IOU_ISSUE_SKIP_COMPLETE;
@@ -805,7 +805,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 		flags |= MSG_DONTWAIT;
 
 	kmsg->msg.msg_get_inq = 1;
-	kmsg->msg.msg_inq = -1U;
+	kmsg->msg.msg_inq = -1;
 	if (req->flags & REQ_F_APOLL_MULTISHOT) {
 		ret = io_recvmsg_multishot(sock, sr, kmsg, flags,
 					   &mshot_finished);
@@ -903,7 +903,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	if (unlikely(ret))
 		goto out_free;
 
-	msg.msg_inq = -1U;
+	msg.msg_inq = -1;
 	msg.msg_flags = 0;
 
 	flags = sr->msg_flags;