xref: /openbmc/linux/io_uring/kbuf.h (revision 4c0a5da0)
1 // SPDX-License-Identifier: GPL-2.0
2 #ifndef IOU_KBUF_H
3 #define IOU_KBUF_H
4 
5 #include <uapi/linux/io_uring.h>
6 
7 struct io_buffer_list {
8 	/*
9 	 * If ->buf_nr_pages is set, then buf_pages/buf_ring are used. If not,
10 	 * then these are classic provided buffers and ->buf_list is used.
11 	 */
12 	union {
13 		struct list_head buf_list;
14 		struct {
15 			struct page **buf_pages;
16 			struct io_uring_buf_ring *buf_ring;
17 		};
18 		struct rcu_head rcu;
19 	};
20 	__u16 bgid;
21 
22 	/* below is for ring provided buffers */
23 	__u16 buf_nr_pages;
24 	__u16 nr_entries;
25 	__u16 head;
26 	__u16 mask;
27 
28 	/* ring mapped provided buffers */
29 	__u8 is_mapped;
30 	/* ring mapped provided buffers, but mmap'ed by application */
31 	__u8 is_mmap;
32 };
33 
34 struct io_buffer {
35 	struct list_head list;
36 	__u64 addr;
37 	__u32 len;
38 	__u16 bid;
39 	__u16 bgid;
40 };
41 
42 void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
43 			      unsigned int issue_flags);
44 void io_destroy_buffers(struct io_ring_ctx *ctx);
45 
46 int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
47 int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags);
48 
49 int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
50 int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
51 
52 int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
53 int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
54 
55 void io_kbuf_mmap_list_free(struct io_ring_ctx *ctx);
56 
57 unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
58 
59 void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);
60 
61 void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid);
62 
63 static inline void io_kbuf_recycle_ring(struct io_kiocb *req)
64 {
65 	/*
66 	 * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
67 	 * the flag and hence ensure that bl->head doesn't get incremented.
68 	 * If the tail has already been incremented, hang on to it.
69 	 * The exception is partial io, that case we should increment bl->head
70 	 * to monopolize the buffer.
71 	 */
72 	if (req->buf_list) {
73 		if (req->flags & REQ_F_PARTIAL_IO) {
74 			/*
75 			 * If we end up here, then the io_uring_lock has
76 			 * been kept held since we retrieved the buffer.
77 			 * For the io-wq case, we already cleared
78 			 * req->buf_list when the buffer was retrieved,
79 			 * hence it cannot be set here for that case.
80 			 */
81 			req->buf_list->head++;
82 			req->buf_list = NULL;
83 		} else {
84 			req->buf_index = req->buf_list->bgid;
85 			req->flags &= ~REQ_F_BUFFER_RING;
86 		}
87 	}
88 }
89 
90 static inline bool io_do_buffer_select(struct io_kiocb *req)
91 {
92 	if (!(req->flags & REQ_F_BUFFER_SELECT))
93 		return false;
94 	return !(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING));
95 }
96 
97 static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
98 {
99 	if (req->flags & REQ_F_BUFFER_SELECTED)
100 		io_kbuf_recycle_legacy(req, issue_flags);
101 	if (req->flags & REQ_F_BUFFER_RING)
102 		io_kbuf_recycle_ring(req);
103 }
104 
105 static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
106 					      struct list_head *list)
107 {
108 	unsigned int ret = IORING_CQE_F_BUFFER | (req->buf_index << IORING_CQE_BUFFER_SHIFT);
109 
110 	if (req->flags & REQ_F_BUFFER_RING) {
111 		if (req->buf_list) {
112 			req->buf_index = req->buf_list->bgid;
113 			req->buf_list->head++;
114 		}
115 		req->flags &= ~REQ_F_BUFFER_RING;
116 	} else {
117 		req->buf_index = req->kbuf->bgid;
118 		list_add(&req->kbuf->list, list);
119 		req->flags &= ~REQ_F_BUFFER_SELECTED;
120 	}
121 
122 	return ret;
123 }
124 
125 static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
126 {
127 	lockdep_assert_held(&req->ctx->completion_lock);
128 
129 	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
130 		return 0;
131 	return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
132 }
133 
134 static inline unsigned int io_put_kbuf(struct io_kiocb *req,
135 				       unsigned issue_flags)
136 {
137 
138 	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
139 		return 0;
140 	return __io_put_kbuf(req, issue_flags);
141 }
142 #endif
143