[PATCH 2/2] liburing: Use the single mmap feature

[Hristo Venev]

Signed-off-by: Hristo Venev <hri...@venev.name>
---
 src/setup.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/src/setup.c b/src/setup.c
index 47b0deb..48c96a0 100644
--- a/src/setup.c
+++ b/src/setup.c
@@ -16,10 +16,30 @@ static int io_uring_mmap(int fd, struct io_uring_params *p,
        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) {
+                       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;
@@ -34,19 +54,14 @@ static int io_uring_mmap(int fd, struct io_uring_params *p,
                                IORING_OFF_SQES);
        if (sq->sqes == MAP_FAILED) {
                ret = -errno;
+               if (cq->ring_ptr != sq->ring_ptr) {
+                       munmap(cq->ring_ptr, cq->ring_sz);
+               }
 err:
                munmap(sq->ring_ptr, sq->ring_sz);
                return ret;
        }
 
-       cq->ring_sz = p->cq_off.cqes + p->cq_entries * sizeof(struct 
io_uring_cqe);
-       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) {
-               ret = -errno;
-               munmap(sq->sqes, *sq->kring_entries * sizeof(struct 
io_uring_sqe));
-               goto err;
-       }
        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;
@@ -105,6 +120,8 @@ void io_uring_queue_exit(struct io_uring *ring)
 
        munmap(sq->sqes, *sq->kring_entries * sizeof(struct io_uring_sqe));
        munmap(sq->ring_ptr, sq->ring_sz);
-       munmap(cq->ring_ptr, cq->ring_sz);
+       if (cq->ring_ptr != sq->ring_ptr) {
+               munmap(cq->ring_ptr, cq->ring_sz);
+       }
        close(ring->ring_fd);
 }
-- 
2.21.0