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
14 static 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
20 static 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
29 static 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
36 static inline void req_ref_put(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_dec(&req->refs);
41 }
42
43 static inline void __io_req_set_refcount(struct io_kiocb *req, int nr)
44 {
45 if (!(req->flags & REQ_F_REFCOUNT)) {
46 req->flags |= REQ_F_REFCOUNT;
47 atomic_set(&req->refs, nr);
48 }
49 }
50
51 static inline void io_req_set_refcount(struct io_kiocb *req)
52 {
53 __io_req_set_refcount(req, 1);
54 }
55 #endif
56
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