[PATCH 07/11] io_uring: use atomic_t for refcounts

[Jens Axboe <axboe@xxxxxxxxx>]

Recently had a regression that turned out to be because
CONFIG_REFCOUNT_FULL was set. Our ref count usage is really simple,
so let's just use atomic_t and get rid of the dependency on the full
reference count checking being enabled or disabled.

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 fs/io_uring.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9a596b819334..05419a152b32 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -360,7 +360,7 @@ struct io_kiocb {
 	};
 	struct list_head	link_list;
 	unsigned int		flags;
-	refcount_t		refs;
+	atomic_t		refs;
 #define REQ_F_NOWAIT		1	/* must not punt to workers */
 #define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
 #define REQ_F_FIXED_FILE	4	/* ctx owns file */
@@ -770,7 +770,7 @@ static void io_cqring_fill_event(struct io_kiocb *req, long res)
 		WRITE_ONCE(ctx->rings->cq_overflow,
 				atomic_inc_return(&ctx->cached_cq_overflow));
 	} else {
-		refcount_inc(&req->refs);
+		atomic_inc(&req->refs);
 		req->result = res;
 		list_add_tail(&req->list, &ctx->cq_overflow_list);
 	}
@@ -852,7 +852,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
 	req->ctx = ctx;
 	req->flags = 0;
 	/* one is dropped after submission, the other at completion */
-	refcount_set(&req->refs, 2);
+	atomic_set(&req->refs, 2);
 	req->result = 0;
 	INIT_IO_WORK(&req->work, io_wq_submit_work);
 	return req;
@@ -1035,13 +1035,13 @@ static void io_put_req_find_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 {
 	io_req_find_next(req, nxtptr);
 
-	if (refcount_dec_and_test(&req->refs))
+	if (atomic_dec_and_test(&req->refs))
 		__io_free_req(req);
 }
 
 static void io_put_req(struct io_kiocb *req)
 {
-	if (refcount_dec_and_test(&req->refs))
+	if (atomic_dec_and_test(&req->refs))
 		io_free_req(req);
 }
 
@@ -1052,14 +1052,14 @@ static void io_put_req(struct io_kiocb *req)
 static void __io_double_put_req(struct io_kiocb *req)
 {
 	/* drop both submit and complete references */
-	if (refcount_sub_and_test(2, &req->refs))
+	if (atomic_sub_and_test(2, &req->refs))
 		__io_free_req(req);
 }
 
 static void io_double_put_req(struct io_kiocb *req)
 {
 	/* drop both submit and complete references */
-	if (refcount_sub_and_test(2, &req->refs))
+	if (atomic_sub_and_test(2, &req->refs))
 		io_free_req(req);
 }
 
@@ -1108,7 +1108,7 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 		io_cqring_fill_event(req, req->result);
 		(*nr_events)++;
 
-		if (refcount_dec_and_test(&req->refs)) {
+		if (atomic_dec_and_test(&req->refs)) {
 			/* If we're not using fixed files, we have to pair the
 			 * completion part with the file put. Use regular
 			 * completions for those, only batch free for fixed
@@ -3169,7 +3169,7 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
 	if (!list_empty(&req->link_list)) {
 		prev = list_entry(req->link_list.prev, struct io_kiocb,
 				  link_list);
-		if (refcount_inc_not_zero(&prev->refs)) {
+		if (atomic_inc_not_zero(&prev->refs)) {
 			list_del_init(&req->link_list);
 			prev->flags &= ~REQ_F_LINK_TIMEOUT;
 		} else
@@ -4237,7 +4237,7 @@ static void io_get_work(struct io_wq_work *work)
 {
 	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
 
-	refcount_inc(&req->refs);
+	atomic_inc(&req->refs);
 }
 
 static int io_sq_offload_start(struct io_ring_ctx *ctx,
@@ -4722,7 +4722,7 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
 			if (req->work.files != files)
 				continue;
 			/* req is being completed, ignore */
-			if (!refcount_inc_not_zero(&req->refs))
+			if (!atomic_inc_not_zero(&req->refs))
 				continue;
 			cancel_req = req;
 			break;
-- 
2.24.0