1#ifndef IOU_REQ_REF_H
2#define IOU_REQ_REF_H
3
4#include <linux/atomic.h>
5#include <linux/io_uring_types.h>
6
7/*
8 * Shamelessly stolen from the mm implementation of page reference checking,
9 * see commit f958d7b528b1 for details.
10 */
11#define req_ref_zero_or_close_to_overflow(req)	\
12	((unsigned int) atomic_read(&(req->refs)) + 127u <= 127u)
13
14static inline bool req_ref_inc_not_zero(struct io_kiocb *req)
15{
16	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
17	return atomic_inc_not_zero(&req->refs);
18}
19
20static inline bool req_ref_put_and_test(struct io_kiocb *req)
21{
22	if (likely(!(req->flags & REQ_F_REFCOUNT)))
23		return true;
24
25	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
26	return atomic_dec_and_test(&req->refs);
27}
28
29static inline void req_ref_get(struct io_kiocb *req)
30{
31	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
32	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
33	atomic_inc(&req->refs);
34}
35
36static inline void __io_req_set_refcount(struct io_kiocb *req, int nr)
37{
38	if (!(req->flags & REQ_F_REFCOUNT)) {
39		req->flags |= REQ_F_REFCOUNT;
40		atomic_set(&req->refs, nr);
41	}
42}
43
44static inline void io_req_set_refcount(struct io_kiocb *req)
45{
46	__io_req_set_refcount(req, 1);
47}
48#endif
49