summaryrefslogtreecommitdiff
path: root/src/setup.c
blob: c53f23484f0763346913aa524aabd612b0084123 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

#include "liburing/compat.h"
#include "liburing/io_uring.h"
#include "liburing.h"

#include "syscall.h"

static void io_uring_unmap_rings(struct io_uring_sq *sq, struct io_uring_cq *cq)
{
	munmap(sq->ring_ptr, sq->ring_sz);
	if (cq->ring_ptr && cq->ring_ptr != sq->ring_ptr)
		munmap(cq->ring_ptr, cq->ring_sz);
}

static int io_uring_mmap(int fd, struct io_uring_params *p,
			 struct io_uring_sq *sq, struct io_uring_cq *cq)
{
	size_t size;
	int ret;

	sq->ring_sz = p->sq_off.array + p->sq_entries * sizeof(unsigned);
	cq->ring_sz = p->cq_off.cqes + p->cq_entries * sizeof(struct io_uring_cqe);

	if (p->features & IORING_FEAT_SINGLE_MMAP) {
		if (cq->ring_sz > sq->ring_sz)
			sq->ring_sz = cq->ring_sz;
		cq->ring_sz = sq->ring_sz;
	}
	sq->ring_ptr = mmap(0, sq->ring_sz, PROT_READ | PROT_WRITE,
			MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_SQ_RING);
	if (sq->ring_ptr == MAP_FAILED)
		return -errno;

	if (p->features & IORING_FEAT_SINGLE_MMAP) {
		cq->ring_ptr = sq->ring_ptr;
	} else {
		cq->ring_ptr = mmap(0, cq->ring_sz, PROT_READ | PROT_WRITE,
				MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_CQ_RING);
		if (cq->ring_ptr == MAP_FAILED) {
			cq->ring_ptr = NULL;
			ret = -errno;
			goto err;
		}
	}

	sq->khead = sq->ring_ptr + p->sq_off.head;
	sq->ktail = sq->ring_ptr + p->sq_off.tail;
	sq->kring_mask = sq->ring_ptr + p->sq_off.ring_mask;
	sq->kring_entries = sq->ring_ptr + p->sq_off.ring_entries;
	sq->kflags = sq->ring_ptr + p->sq_off.flags;
	sq->kdropped = sq->ring_ptr + p->sq_off.dropped;
	sq->array = sq->ring_ptr + p->sq_off.array;

	size = p->sq_entries * sizeof(struct io_uring_sqe);
	sq->sqes = mmap(0, size, PROT_READ | PROT_WRITE,
				MAP_SHARED | MAP_POPULATE, fd,
				IORING_OFF_SQES);
	if (sq->sqes == MAP_FAILED) {
		ret = -errno;
err:
		io_uring_unmap_rings(sq, cq);
		return ret;
	}

	cq->khead = cq->ring_ptr + p->cq_off.head;
	cq->ktail = cq->ring_ptr + p->cq_off.tail;
	cq->kring_mask = cq->ring_ptr + p->cq_off.ring_mask;
	cq->kring_entries = cq->ring_ptr + p->cq_off.ring_entries;
	cq->koverflow = cq->ring_ptr + p->cq_off.overflow;
	cq->cqes = cq->ring_ptr + p->cq_off.cqes;
	return 0;
}

/*
 * For users that want to specify sq_thread_cpu or sq_thread_idle, this
 * interface is a convenient helper for mmap()ing the rings.
 * Returns -1 on error, or zero on success.  On success, 'ring'
 * contains the necessary information to read/write to the rings.
 */
int io_uring_queue_mmap(int fd, struct io_uring_params *p, struct io_uring *ring)
{
	int ret;

	memset(ring, 0, sizeof(*ring));
	ret = io_uring_mmap(fd, p, &ring->sq, &ring->cq);
	if (!ret) {
		ring->flags = p->flags;
		ring->ring_fd = fd;
	}
	return ret;
}

/*
 * Ensure that the mmap'ed rings aren't available to a child after a fork(2).
 * This uses madvise(..., MADV_DONTFORK) on the mmap'ed ranges.
 */
int io_uring_ring_dontfork(struct io_uring *ring)
{
	size_t len;
	int ret;

	if (!ring->sq.ring_ptr || !ring->sq.sqes || !ring->cq.ring_ptr)
		return -EINVAL;

	len = *ring->sq.kring_entries * sizeof(struct io_uring_sqe);
	ret = madvise(ring->sq.sqes, len, MADV_DONTFORK);
	if (ret == -1)
		return -errno;

	len = ring->sq.ring_sz;
	ret = madvise(ring->sq.ring_ptr, len, MADV_DONTFORK);
	if (ret == -1)
		return -errno;

	if (ring->cq.ring_ptr != ring->sq.ring_ptr) {
		len = ring->cq.ring_sz;
		ret = madvise(ring->cq.ring_ptr, len, MADV_DONTFORK);
		if (ret == -1)
			return -errno;
	}

	return 0;
}

int io_uring_queue_init_params(unsigned entries, struct io_uring *ring,
			       struct io_uring_params *p)
{
	int fd, ret;

	fd = __sys_io_uring_setup(entries, p);
	if (fd < 0)
		return -errno;

	ret = io_uring_queue_mmap(fd, p, ring);
	if (ret)
		close(fd);

	return ret;
}

/*
 * Returns -1 on error, or zero on success. On success, 'ring'
 * contains the necessary information to read/write to the rings.
 */
int io_uring_queue_init(unsigned entries, struct io_uring *ring, unsigned flags)
{
	struct io_uring_params p;

	memset(&p, 0, sizeof(p));
	p.flags = flags;

	return io_uring_queue_init_params(entries, ring, &p);
}

void io_uring_queue_exit(struct io_uring *ring)
{
	struct io_uring_sq *sq = &ring->sq;
	struct io_uring_cq *cq = &ring->cq;

	munmap(sq->sqes, *sq->kring_entries * sizeof(struct io_uring_sqe));
	io_uring_unmap_rings(sq, cq);
	close(ring->ring_fd);
}