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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 "compat.h"
#include "io_uring.h"
#include "liburing.h"
#include "barrier.h"
static int __io_uring_get_completion(struct io_uring *ring,
struct io_uring_cqe **cqe_ptr, int wait)
{
struct io_uring_cq *cq = &ring->cq;
const unsigned mask = *cq->kring_mask;
unsigned head;
int ret;
*cqe_ptr = NULL;
head = *cq->khead;
do {
read_barrier();
if (head != *cq->ktail) {
*cqe_ptr = &cq->cqes[head & mask];
break;
}
if (!wait)
break;
ret = io_uring_enter(ring->ring_fd, 0, 1,
IORING_ENTER_GETEVENTS, NULL, _NSIG / 8);
if (ret < 0)
return -errno;
} while (1);
if (*cqe_ptr) {
*cq->khead = head + 1;
write_barrier();
}
return 0;
}
/*
* Return an IO completion, if one is readily available
*/
int io_uring_get_completion(struct io_uring *ring,
struct io_uring_cqe **cqe_ptr)
{
return __io_uring_get_completion(ring, cqe_ptr, 0);
}
/*
* Return an IO completion, waiting for it if necessary
*/
int io_uring_wait_completion(struct io_uring *ring,
struct io_uring_cqe **cqe_ptr)
{
return __io_uring_get_completion(ring, cqe_ptr, 1);
}
/*
* Submit sqes acquired from io_uring_get_sqe() to the kernel.
*
* Returns number of sqes submitted
*/
int io_uring_submit(struct io_uring *ring)
{
struct io_uring_sq *sq = &ring->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->sqe_head == sq->sqe_tail)
return 0;
/*
* Fill in sqes that we have queued up, adding them to the kernel ring
*/
submitted = 0;
ktail = ktail_next = *sq->ktail;
while (sq->sqe_head < sq->sqe_tail) {
ktail_next++;
read_barrier();
if (ktail_next == *sq->khead)
break;
sq->array[ktail & mask] = sq->sqe_head & mask;
ktail = ktail_next;
sq->sqe_head++;
submitted++;
}
if (!submitted)
return 0;
if (*sq->ktail != ktail) {
write_barrier();
*sq->ktail = ktail;
write_barrier();
}
submit:
return io_uring_enter(ring->ring_fd, submitted, 0,
IORING_ENTER_GETEVENTS, NULL, _NSIG / 8);
}
/*
* Return an sqe 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 sqe, or NULL if we're full.
*/
struct io_uring_sqe *io_uring_get_sqe(struct io_uring *ring)
{
struct io_uring_sq *sq = &ring->sq;
unsigned next = sq->sqe_tail + 1;
struct io_uring_sqe *sqe;
/*
* All sqes are used
*/
if (next - sq->sqe_head > *sq->kring_entries)
return NULL;
sqe = &sq->sqes[sq->sqe_tail & *sq->kring_mask];
sq->sqe_tail = next;
return sqe;
}
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