[thirdparty/linux.git] / io_uring / waitid.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Support for async notification of waitid
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/compat.h>
#include <linux/io_uring.h>

#include <uapi/linux/io_uring.h>

#include "io_uring.h"
#include "cancel.h"
#include "waitid.h"
#include "../kernel/exit.h"

static void io_waitid_cb(struct io_kiocb *req, struct io_tw_state *ts);

#define IO_WAITID_CANCEL_FLAG	BIT(31)
#define IO_WAITID_REF_MASK	GENMASK(30, 0)

struct io_waitid {
	struct file *file;
	int which;
	pid_t upid;
	int options;
	atomic_t refs;
	struct wait_queue_head *head;
	struct siginfo __user *infop;
	struct waitid_info info;
};

static void io_waitid_free(struct io_kiocb *req)
{
	struct io_waitid_async *iwa = req->async_data;

	put_pid(iwa->wo.wo_pid);
	kfree(req->async_data);
	req->async_data = NULL;
	req->flags &= ~REQ_F_ASYNC_DATA;
}

#ifdef CONFIG_COMPAT
static bool io_waitid_compat_copy_si(struct io_waitid *iw, int signo)
{
	struct compat_siginfo __user *infop;
	bool ret;

	infop = (struct compat_siginfo __user *) iw->infop;

	if (!user_write_access_begin(infop, sizeof(*infop)))
		return false;

	unsafe_put_user(signo, &infop->si_signo, Efault);
	unsafe_put_user(0, &infop->si_errno, Efault);
	unsafe_put_user(iw->info.cause, &infop->si_code, Efault);
	unsafe_put_user(iw->info.pid, &infop->si_pid, Efault);
	unsafe_put_user(iw->info.uid, &infop->si_uid, Efault);
	unsafe_put_user(iw->info.status, &infop->si_status, Efault);
	ret = true;
done:
	user_write_access_end();
	return ret;
Efault:
	ret = false;
	goto done;
}
#endif

static bool io_waitid_copy_si(struct io_kiocb *req, int signo)
{
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
	bool ret;

	if (!iw->infop)
		return true;

#ifdef CONFIG_COMPAT
	if (req->ctx->compat)
		return io_waitid_compat_copy_si(iw, signo);
#endif

	if (!user_write_access_begin(iw->infop, sizeof(*iw->infop)))
		return false;

	unsafe_put_user(signo, &iw->infop->si_signo, Efault);
	unsafe_put_user(0, &iw->infop->si_errno, Efault);
	unsafe_put_user(iw->info.cause, &iw->infop->si_code, Efault);
	unsafe_put_user(iw->info.pid, &iw->infop->si_pid, Efault);
	unsafe_put_user(iw->info.uid, &iw->infop->si_uid, Efault);
	unsafe_put_user(iw->info.status, &iw->infop->si_status, Efault);
	ret = true;
done:
	user_write_access_end();
	return ret;
Efault:
	ret = false;
	goto done;
}

static int io_waitid_finish(struct io_kiocb *req, int ret)
{
	int signo = 0;

	if (ret > 0) {
		signo = SIGCHLD;
		ret = 0;
	}

	if (!io_waitid_copy_si(req, signo))
		ret = -EFAULT;
	io_waitid_free(req);
	return ret;
}

static void io_waitid_complete(struct io_kiocb *req, int ret)
{
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
	struct io_tw_state ts = { .locked = true };

	/* anyone completing better be holding a reference */
	WARN_ON_ONCE(!(atomic_read(&iw->refs) & IO_WAITID_REF_MASK));

	lockdep_assert_held(&req->ctx->uring_lock);

	/*
	 * Did cancel find it meanwhile?
	 */
	if (hlist_unhashed(&req->hash_node))
		return;

	hlist_del_init(&req->hash_node);

	ret = io_waitid_finish(req, ret);
	if (ret < 0)
		req_set_fail(req);
	io_req_set_res(req, ret, 0);
	io_req_task_complete(req, &ts);
}

static bool __io_waitid_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)
{
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
	struct io_waitid_async *iwa = req->async_data;

	/*
	 * Mark us canceled regardless of ownership. This will prevent a
	 * potential retry from a spurious wakeup.
	 */
	atomic_or(IO_WAITID_CANCEL_FLAG, &iw->refs);

	/* claim ownership */
	if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK)
		return false;

	spin_lock_irq(&iw->head->lock);
	list_del_init(&iwa->wo.child_wait.entry);
	spin_unlock_irq(&iw->head->lock);
	io_waitid_complete(req, -ECANCELED);
	return true;
}

int io_waitid_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
		     unsigned int issue_flags)
{
	struct hlist_node *tmp;
	struct io_kiocb *req;
	int nr = 0;

	if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED))
		return -ENOENT;

	io_ring_submit_lock(ctx, issue_flags);
	hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) {
		if (req->cqe.user_data != cd->data &&
		    !(cd->flags & IORING_ASYNC_CANCEL_ANY))
			continue;
		if (__io_waitid_cancel(ctx, req))
			nr++;
		if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
			break;
	}
	io_ring_submit_unlock(ctx, issue_flags);

	if (nr)
		return nr;

	return -ENOENT;
}

bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
			  bool cancel_all)
{
	struct hlist_node *tmp;
	struct io_kiocb *req;
	bool found = false;

	lockdep_assert_held(&ctx->uring_lock);

	hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) {
		if (!io_match_task_safe(req, task, cancel_all))
			continue;
		__io_waitid_cancel(ctx, req);
		found = true;
	}

	return found;
}

static inline bool io_waitid_drop_issue_ref(struct io_kiocb *req)
{
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
	struct io_waitid_async *iwa = req->async_data;

	if (!atomic_sub_return(1, &iw->refs))
		return false;

	/*
	 * Wakeup triggered, racing with us. It was prevented from
	 * completing because of that, queue up the tw to do that.
	 */
	req->io_task_work.func = io_waitid_cb;
	io_req_task_work_add(req);
	remove_wait_queue(iw->head, &iwa->wo.child_wait);
	return true;
}

static void io_waitid_cb(struct io_kiocb *req, struct io_tw_state *ts)
{
	struct io_waitid_async *iwa = req->async_data;
	struct io_ring_ctx *ctx = req->ctx;
	int ret;

	io_tw_lock(ctx, ts);

	ret = __do_wait(&iwa->wo);

	/*
	 * If we get -ERESTARTSYS here, we need to re-arm and check again
	 * to ensure we get another callback. If the retry works, then we can
	 * just remove ourselves from the waitqueue again and finish the
	 * request.
	 */
	if (unlikely(ret == -ERESTARTSYS)) {
		struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);

		/* Don't retry if cancel found it meanwhile */
		ret = -ECANCELED;
		if (!(atomic_read(&iw->refs) & IO_WAITID_CANCEL_FLAG)) {
			iw->head = &current->signal->wait_chldexit;
			add_wait_queue(iw->head, &iwa->wo.child_wait);
			ret = __do_wait(&iwa->wo);
			if (ret == -ERESTARTSYS) {
				/* retry armed, drop our ref */
				io_waitid_drop_issue_ref(req);
				return;
			}

			remove_wait_queue(iw->head, &iwa->wo.child_wait);
		}
	}

	io_waitid_complete(req, ret);
}

static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode,
			  int sync, void *key)
{
	struct wait_opts *wo = container_of(wait, struct wait_opts, child_wait);
	struct io_waitid_async *iwa = container_of(wo, struct io_waitid_async, wo);
	struct io_kiocb *req = iwa->req;
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
	struct task_struct *p = key;

	if (!pid_child_should_wake(wo, p))
		return 0;

	/* cancel is in progress */
	if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK)
		return 1;

	req->io_task_work.func = io_waitid_cb;
	io_req_task_work_add(req);
	list_del_init(&wait->entry);
	return 1;
}

int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);

	if (sqe->addr || sqe->buf_index || sqe->addr3 || sqe->waitid_flags)
		return -EINVAL;

	iw->which = READ_ONCE(sqe->len);
	iw->upid = READ_ONCE(sqe->fd);
	iw->options = READ_ONCE(sqe->file_index);
	iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2));
	return 0;
}

int io_waitid(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
	struct io_ring_ctx *ctx = req->ctx;
	struct io_waitid_async *iwa;
	int ret;

	if (io_alloc_async_data(req))
		return -ENOMEM;

	iwa = req->async_data;
	iwa->req = req;

	ret = kernel_waitid_prepare(&iwa->wo, iw->which, iw->upid, &iw->info,
					iw->options, NULL);
	if (ret)
		goto done;

	/*
	 * Mark the request as busy upfront, in case we're racing with the
	 * wakeup. If we are, then we'll notice when we drop this initial
	 * reference again after arming.
	 */
	atomic_set(&iw->refs, 1);

	/*
	 * Cancel must hold the ctx lock, so there's no risk of cancelation
	 * finding us until a) we remain on the list, and b) the lock is
	 * dropped. We only need to worry about racing with the wakeup
	 * callback.
	 */
	io_ring_submit_lock(ctx, issue_flags);
	hlist_add_head(&req->hash_node, &ctx->waitid_list);

	init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait);
	iwa->wo.child_wait.private = req->task;
	iw->head = &current->signal->wait_chldexit;
	add_wait_queue(iw->head, &iwa->wo.child_wait);

	ret = __do_wait(&iwa->wo);
	if (ret == -ERESTARTSYS) {
		/*
		 * Nobody else grabbed a reference, it'll complete when we get
		 * a waitqueue callback, or if someone cancels it.
		 */
		if (!io_waitid_drop_issue_ref(req)) {
			io_ring_submit_unlock(ctx, issue_flags);
			return IOU_ISSUE_SKIP_COMPLETE;
		}

		/*
		 * Wakeup triggered, racing with us. It was prevented from
		 * completing because of that, queue up the tw to do that.
		 */
		io_ring_submit_unlock(ctx, issue_flags);
		return IOU_ISSUE_SKIP_COMPLETE;
	}

	hlist_del_init(&req->hash_node);
	remove_wait_queue(iw->head, &iwa->wo.child_wait);
	ret = io_waitid_finish(req, ret);

	io_ring_submit_unlock(ctx, issue_flags);
done:
	if (ret < 0)
		req_set_fail(req);
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}
Commit	Line	Data
f31ecf67 JA	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Support for async notification of waitid
	4	*/
	5	#include <linux/kernel.h>
	6	#include <linux/errno.h>
	7	#include <linux/fs.h>
	8	#include <linux/file.h>
	9	#include <linux/compat.h>
	10	#include <linux/io_uring.h>
	11
	12	#include <uapi/linux/io_uring.h>
	13
	14	#include "io_uring.h"
	15	#include "cancel.h"
	16	#include "waitid.h"
	17	#include "../kernel/exit.h"
	18
	19	static void io_waitid_cb(struct io_kiocb req, struct io_tw_state ts);
	20
	21	#define IO_WAITID_CANCEL_FLAG BIT(31)
	22	#define IO_WAITID_REF_MASK GENMASK(30, 0)
	23
	24	struct io_waitid {
	25	struct file *file;
	26	int which;
	27	pid_t upid;
	28	int options;
	29	atomic_t refs;
	30	struct wait_queue_head *head;
	31	struct siginfo __user *infop;
	32	struct waitid_info info;
	33	};
	34
	35	static void io_waitid_free(struct io_kiocb *req)
	36	{
	37	struct io_waitid_async *iwa = req->async_data;
	38
	39	put_pid(iwa->wo.wo_pid);
	40	kfree(req->async_data);
	41	req->async_data = NULL;
	42	req->flags &= ~REQ_F_ASYNC_DATA;
	43	}
	44
	45	#ifdef CONFIG_COMPAT
	46	static bool io_waitid_compat_copy_si(struct io_waitid *iw, int signo)
	47	{
	48	struct compat_siginfo __user *infop;
	49	bool ret;
	50
	51	infop = (struct compat_siginfo __user *) iw->infop;
	52
	53	if (!user_write_access_begin(infop, sizeof(*infop)))
	54	return false;
	55
	56	unsafe_put_user(signo, &infop->si_signo, Efault);
	57	unsafe_put_user(0, &infop->si_errno, Efault);
	58	unsafe_put_user(iw->info.cause, &infop->si_code, Efault);
	59	unsafe_put_user(iw->info.pid, &infop->si_pid, Efault);
	60	unsafe_put_user(iw->info.uid, &infop->si_uid, Efault);
	61	unsafe_put_user(iw->info.status, &infop->si_status, Efault);
	62	ret = true;
	63	done:
	64	user_write_access_end();
65	return ret;
66	Efault:
67	ret = false;
68	goto done;
69	}
70	#endif
71
72	static bool io_waitid_copy_si(struct io_kiocb *req, int signo)
73	{
74	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
75	bool ret;
76
77	if (!iw->infop)
78	return true;
79
80	#ifdef CONFIG_COMPAT
81	if (req->ctx->compat)
82	return io_waitid_compat_copy_si(iw, signo);
83	#endif
84
85	if (!user_write_access_begin(iw->infop, sizeof(*iw->infop)))
86	return false;
87
88	unsafe_put_user(signo, &iw->infop->si_signo, Efault);
89	unsafe_put_user(0, &iw->infop->si_errno, Efault);
90	unsafe_put_user(iw->info.cause, &iw->infop->si_code, Efault);
91	unsafe_put_user(iw->info.pid, &iw->infop->si_pid, Efault);
92	unsafe_put_user(iw->info.uid, &iw->infop->si_uid, Efault);
93	unsafe_put_user(iw->info.status, &iw->infop->si_status, Efault);
94	ret = true;
95	done:
96	user_write_access_end();
97	return ret;
98	Efault:
99	ret = false;
100	goto done;
101	}
102
103	static int io_waitid_finish(struct io_kiocb *req, int ret)
104	{
105	int signo = 0;
106
107	if (ret > 0) {
108	signo = SIGCHLD;
109	ret = 0;
110	}
111
112	if (!io_waitid_copy_si(req, signo))
113	ret = -EFAULT;
114	io_waitid_free(req);
115	return ret;
116	}
117
118	static void io_waitid_complete(struct io_kiocb *req, int ret)
119	{
120	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
121	struct io_tw_state ts = { .locked = true };
122
123	/* anyone completing better be holding a reference */
124	WARN_ON_ONCE(!(atomic_read(&iw->refs) & IO_WAITID_REF_MASK));
125
126	lockdep_assert_held(&req->ctx->uring_lock);
127
128	/*
129	* Did cancel find it meanwhile?
130	*/
131	if (hlist_unhashed(&req->hash_node))
132	return;
133
134	hlist_del_init(&req->hash_node);
135
136	ret = io_waitid_finish(req, ret);
137	if (ret < 0)
138	req_set_fail(req);
139	io_req_set_res(req, ret, 0);
140	io_req_task_complete(req, &ts);
141	}
142
143	static bool __io_waitid_cancel(struct io_ring_ctx ctx, struct io_kiocb req)
144	{
145	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
146	struct io_waitid_async *iwa = req->async_data;
147
148	/*
149	* Mark us canceled regardless of ownership. This will prevent a
150	* potential retry from a spurious wakeup.
151	*/
152	atomic_or(IO_WAITID_CANCEL_FLAG, &iw->refs);
153
154	/* claim ownership */
155	if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK)
156	return false;
157
158	spin_lock_irq(&iw->head->lock);
159	list_del_init(&iwa->wo.child_wait.entry);
160	spin_unlock_irq(&iw->head->lock);
161	io_waitid_complete(req, -ECANCELED);
162	return true;
163	}
164
165	int io_waitid_cancel(struct io_ring_ctx ctx, struct io_cancel_data cd,
166	unsigned int issue_flags)
167	{
168	struct hlist_node *tmp;
169	struct io_kiocb *req;
170	int nr = 0;
171
172	if (cd->flags & (IORING_ASYNC_CANCEL_FD\|IORING_ASYNC_CANCEL_FD_FIXED))
173	return -ENOENT;
174
175	io_ring_submit_lock(ctx, issue_flags);
176	hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) {
177	if (req->cqe.user_data != cd->data &&
178	!(cd->flags & IORING_ASYNC_CANCEL_ANY))
179	continue;
180	if (__io_waitid_cancel(ctx, req))
181	nr++;
182	if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
183	break;
184	}
185	io_ring_submit_unlock(ctx, issue_flags);
186
187	if (nr)
188	return nr;
189
190	return -ENOENT;
191	}
192
193	bool io_waitid_remove_all(struct io_ring_ctx ctx, struct task_struct task,
194	bool cancel_all)
195	{
196	struct hlist_node *tmp;
197	struct io_kiocb *req;
198	bool found = false;
199
200	lockdep_assert_held(&ctx->uring_lock);
201
202	hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) {
203	if (!io_match_task_safe(req, task, cancel_all))
204	continue;
205	__io_waitid_cancel(ctx, req);
206	found = true;
207	}
208
209	return found;
210	}
211
212	static inline bool io_waitid_drop_issue_ref(struct io_kiocb *req)
213	{
214	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
215	struct io_waitid_async *iwa = req->async_data;
216
217	if (!atomic_sub_return(1, &iw->refs))
218	return false;
219
220	/*
221	* Wakeup triggered, racing with us. It was prevented from
222	* completing because of that, queue up the tw to do that.
223	*/
224	req->io_task_work.func = io_waitid_cb;
225	io_req_task_work_add(req);
226	remove_wait_queue(iw->head, &iwa->wo.child_wait);
227	return true;
228	}
229
230	static void io_waitid_cb(struct io_kiocb req, struct io_tw_state ts)
231	{
232	struct io_waitid_async *iwa = req->async_data;
233	struct io_ring_ctx *ctx = req->ctx;
234	int ret;
235
236	io_tw_lock(ctx, ts);
237
238	ret = __do_wait(&iwa->wo);
239
240	/*
241	* If we get -ERESTARTSYS here, we need to re-arm and check again
242	* to ensure we get another callback. If the retry works, then we can
243	* just remove ourselves from the waitqueue again and finish the
244	* request.
245	*/
246	if (unlikely(ret == -ERESTARTSYS)) {
247	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
248
249	/* Don't retry if cancel found it meanwhile */
250	ret = -ECANCELED;
251	if (!(atomic_read(&iw->refs) & IO_WAITID_CANCEL_FLAG)) {
252	iw->head = &current->signal->wait_chldexit;
253	add_wait_queue(iw->head, &iwa->wo.child_wait);
254	ret = __do_wait(&iwa->wo);
255	if (ret == -ERESTARTSYS) {
256	/* retry armed, drop our ref */
257	io_waitid_drop_issue_ref(req);
258	return;
259	}
260
261	remove_wait_queue(iw->head, &iwa->wo.child_wait);
262	}
263	}
264
265	io_waitid_complete(req, ret);
266	}
267
268	static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode,
269	int sync, void *key)
270	{
271	struct wait_opts *wo = container_of(wait, struct wait_opts, child_wait);
272	struct io_waitid_async *iwa = container_of(wo, struct io_waitid_async, wo);
273	struct io_kiocb *req = iwa->req;
274	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
275	struct task_struct *p = key;
276
277	if (!pid_child_should_wake(wo, p))
278	return 0;
279
280	/* cancel is in progress */
281	if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK)
282	return 1;
283
284	req->io_task_work.func = io_waitid_cb;
285	io_req_task_work_add(req);
286	list_del_init(&wait->entry);
287	return 1;
288	}
289
290	int io_waitid_prep(struct io_kiocb req, const struct io_uring_sqe sqe)
291	{
292	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
293
294	if (sqe->addr \|\| sqe->buf_index \|\| sqe->addr3 \|\| sqe->waitid_flags)
295	return -EINVAL;
296
297	iw->which = READ_ONCE(sqe->len);
298	iw->upid = READ_ONCE(sqe->fd);
299	iw->options = READ_ONCE(sqe->file_index);
300	iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2));
301	return 0;
302	}
303
304	int io_waitid(struct io_kiocb *req, unsigned int issue_flags)
305	{
306	struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
307	struct io_ring_ctx *ctx = req->ctx;
308	struct io_waitid_async *iwa;
309	int ret;
310
311	if (io_alloc_async_data(req))
312	return -ENOMEM;
313
314	iwa = req->async_data;
315	iwa->req = req;
316
317	ret = kernel_waitid_prepare(&iwa->wo, iw->which, iw->upid, &iw->info,
318	iw->options, NULL);
319	if (ret)
320	goto done;
321
322	/*
323	* Mark the request as busy upfront, in case we're racing with the
324	* wakeup. If we are, then we'll notice when we drop this initial
325	* reference again after arming.
326	*/
327	atomic_set(&iw->refs, 1);
328
329	/*
330	* Cancel must hold the ctx lock, so there's no risk of cancelation
331	* finding us until a) we remain on the list, and b) the lock is
332	* dropped. We only need to worry about racing with the wakeup
333	* callback.
334	*/
335	io_ring_submit_lock(ctx, issue_flags);
336	hlist_add_head(&req->hash_node, &ctx->waitid_list);
337
338	init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait);
339	iwa->wo.child_wait.private = req->task;
340	iw->head = &current->signal->wait_chldexit;
341	add_wait_queue(iw->head, &iwa->wo.child_wait);
342
343	ret = __do_wait(&iwa->wo);
344	if (ret == -ERESTARTSYS) {
345	/*
346	* Nobody else grabbed a reference, it'll complete when we get
347	* a waitqueue callback, or if someone cancels it.
348	*/
349	if (!io_waitid_drop_issue_ref(req)) {
350	io_ring_submit_unlock(ctx, issue_flags);
351	return IOU_ISSUE_SKIP_COMPLETE;
352	}
353
354	/*
355	* Wakeup triggered, racing with us. It was prevented from
356	* completing because of that, queue up the tw to do that.
357	*/
358	io_ring_submit_unlock(ctx, issue_flags);
359	return IOU_ISSUE_SKIP_COMPLETE;
360	}
361
362	hlist_del_init(&req->hash_node);
363	remove_wait_queue(iw->head, &iwa->wo.child_wait);
364	ret = io_waitid_finish(req, ret);
365
366	io_ring_submit_unlock(ctx, issue_flags);
367	done:
368	if (ret < 0)
369	req_set_fail(req);
370	io_req_set_res(req, ret, 0);
371	return IOU_OK;
372	}