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#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "io_uring.h"
#include "liburing.h"
#include "barrier.h"
/*
* Return an IO completion, waiting for it it necessary.
*/
int io_uring_get_completion(int fd, struct io_uring_cq *cq,
struct io_uring_event **ev_ptr)
{
const unsigned mask = *cq->kring_mask;
struct io_uring_event *ev = NULL;
unsigned head;
int ret;
head = *cq->khead;
do {
read_barrier();
if (head != *cq->ktail) {
ev = &cq->events[head & mask];
break;
}
ret = io_uring_enter(fd, 0, 1, IORING_ENTER_GETEVENTS);
if (ret < 0)
return -errno;
} while (1);
if (ev) {
*cq->khead = head + 1;
write_barrier();
}
*ev_ptr = ev;
return 0;
}
/*
* Submit iocbs acquired from io_uring_get_iocb() to the kernel.
*
* Returns number of iocbs submitted
*/
int io_uring_submit(int fd, struct io_uring_sq *sq)
{
const unsigned mask = *sq->kring_mask;
unsigned ktail, ktail_next, submitted;
/*
* If we have pending IO in the kring, submit it first
*/
read_barrier();
if (*sq->khead != *sq->ktail) {
submitted = *sq->kring_entries;
goto submit;
}
if (sq->iocb_head == sq->iocb_tail)
return 0;
/*
* Fill in iocbs that we have queued up, adding them to the kernel ring
*/
submitted = 0;
ktail = ktail_next = *sq->ktail;
while (sq->iocb_head < sq->iocb_tail) {
ktail_next++;
read_barrier();
if (ktail_next == *sq->khead)
break;
sq->array[ktail & mask] = sq->iocb_head & mask;
ktail = ktail_next;
sq->iocb_head++;
submitted++;
}
if (!submitted)
return 0;
if (*sq->ktail != ktail) {
write_barrier();
*sq->ktail = ktail;
write_barrier();
}
submit:
return io_uring_enter(fd, submitted, 0, IORING_ENTER_GETEVENTS);
}
/*
* Return an iocb to fill. Application must later call io_uring_submit()
* when it's ready to tell the kernel about it. The caller may call this
* function multiple times before calling io_uring_submit().
*
* Returns a vacant iocb, or NULL if we're full.
*/
struct io_uring_iocb *io_uring_get_iocb(struct io_uring_sq *sq)
{
unsigned next = sq->iocb_tail + 1;
struct io_uring_iocb *iocb;
/*
* All iocbs are used
*/
if (next - sq->iocb_head > *sq->kring_entries)
return NULL;
iocb = &sq->iocbs[sq->iocb_tail & *sq->kring_mask];
sq->iocb_tail = next;
return iocb;
}
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;
void *ptr;
int ret;
sq->ring_sz = p->sq_off.array + p->sq_entries * sizeof(unsigned);
ptr = mmap(0, sq->ring_sz, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_SQ_RING);
if (ptr == MAP_FAILED)
return -errno;
sq->khead = ptr + p->sq_off.head;
sq->ktail = ptr + p->sq_off.tail;
sq->kring_mask = ptr + p->sq_off.ring_mask;
sq->kring_entries = ptr + p->sq_off.ring_entries;
sq->kflags = ptr + p->sq_off.flags;
sq->kdropped = ptr + p->sq_off.dropped;
sq->array = ptr + p->sq_off.array;
size = p->sq_entries * sizeof(struct io_uring_iocb);
sq->iocbs = mmap(0, size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_POPULATE, fd,
IORING_OFF_IOCB);
if (sq->iocbs == MAP_FAILED) {
ret = -errno;
err:
munmap(sq->khead, sq->ring_sz);
return ret;
}
cq->ring_sz = p->cq_off.events + p->cq_entries * sizeof(struct io_uring_event);
ptr = mmap(0, cq->ring_sz, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_CQ_RING);
if (ptr == MAP_FAILED) {
ret = -errno;
munmap(sq->iocbs, p->sq_entries * sizeof(struct io_uring_iocb));
goto err;
}
cq->khead = ptr + p->cq_off.head;
cq->ktail = ptr + p->cq_off.tail;
cq->kring_mask = ptr + p->cq_off.ring_mask;
cq->kring_entries = ptr + p->cq_off.ring_entries;
cq->koverflow = ptr + p->cq_off.overflow;
cq->events = ptr + p->cq_off.events;
return fd;
}
/*
* Returns -1 on error, or an 'fd' on success. On success, 'sq' and 'cq'
* contain the necessary information to read/write to the rings.
*/
int io_uring_queue_init(unsigned entries, struct io_uring_params *p,
struct iovec *iovecs, struct io_uring_sq *sq,
struct io_uring_cq *cq)
{
int fd;
fd = io_uring_setup(entries, iovecs, p);
if (fd < 0)
return fd;
memset(sq, 0, sizeof(*sq));
memset(cq, 0, sizeof(*cq));
return io_uring_mmap(fd, p, sq, cq);
}
void io_uring_queue_exit(int fd, struct io_uring_sq *sq, struct io_uring_cq *cq)
{
munmap(sq->iocbs, *sq->kring_entries * sizeof(struct io_uring_iocb));
munmap(sq->khead, sq->ring_sz);
munmap(cq->khead, cq->ring_sz);
close(fd);
}
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