refs.h

 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_atomic(struct io_kiocb *req)
21{
22	WARN_ON_ONCE(!(data_race(req->flags) & REQ_F_REFCOUNT));
23	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
24	return atomic_dec_and_test(&req->refs);
25}
26
27static inline bool req_ref_put_and_test(struct io_kiocb *req)
28{
29	if (likely(!(req->flags & REQ_F_REFCOUNT)))
30		return true;
31
32	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
33	return atomic_dec_and_test(&req->refs);
34}
35
36static inline void req_ref_get(struct io_kiocb *req)
37{
38	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
39	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
40	atomic_inc(&req->refs);
41}
42
43static inline void req_ref_put(struct io_kiocb *req)
44{
45	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
46	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
47	atomic_dec(&req->refs);
48}
49
50static inline void __io_req_set_refcount(struct io_kiocb *req, int nr)
51{
52	if (!(req->flags & REQ_F_REFCOUNT)) {
53		req->flags |= REQ_F_REFCOUNT;
54		atomic_set(&req->refs, nr);
55	}
56}
57
58static inline void io_req_set_refcount(struct io_kiocb *req)
59{
60	__io_req_set_refcount(req, 1);
61}
62#endif