io_uring/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
  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