io_uring: replace find_next() out param with ret

Generally, it's better to return a value directly than having out
parameter. It's cleaner and saves from some kinds of ugly bugs.
May also be faster.

Return next request from io_req_find_next() and friends directly
instead of passing out parameter.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a0aea78162a6f46836ae0f419ae28d717881e05e..0234dc2c9625792d74a900c4a335bfbcd74b8a11 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1578,7 +1578,7 @@ out:
                io_cqring_ev_posted(ctx);
 }
 
-static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
+static struct io_kiocb *io_req_link_next(struct io_kiocb *req)
 {
        struct io_kiocb *nxt;
 
@@ -1588,13 +1588,13 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
         * safe side.
         */
        if (unlikely(list_empty(&req->link_list)))
-               return;
+               return NULL;
 
        nxt = list_first_entry(&req->link_list, struct io_kiocb, link_list);
        list_del_init(&req->link_list);
        if (!list_empty(&nxt->link_list))
                nxt->flags |= REQ_F_LINK_HEAD;
-       *nxtptr = nxt;
+       return nxt;
 }
 
 /*
@@ -1637,10 +1637,10 @@ static void io_fail_links(struct io_kiocb *req)
        io_cqring_ev_posted(ctx);
 }
 
-static void io_req_find_next(struct io_kiocb *req, struct io_kiocb **nxt)
+static struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 {
        if (likely(!(req->flags & REQ_F_LINK_HEAD)))
-               return;
+               return NULL;
        req->flags &= ~REQ_F_LINK_HEAD;
 
        if (req->flags & REQ_F_LINK_TIMEOUT)
@@ -1652,10 +1652,10 @@ static void io_req_find_next(struct io_kiocb *req, struct io_kiocb **nxt)
         * dependencies to the next request. In case of failure, fail the rest
         * of the chain.
         */
-       if (req->flags & REQ_F_FAIL_LINK)
-               io_fail_links(req);
-       else
-               io_req_link_next(req, nxt);
+       if (likely(!(req->flags & REQ_F_FAIL_LINK)))
+               return io_req_link_next(req);
+       io_fail_links(req);
+       return NULL;
 }
 
 static void __io_req_task_cancel(struct io_kiocb *req, int error)
@@ -1718,9 +1718,8 @@ static void io_req_task_queue(struct io_kiocb *req)
 
 static void io_queue_next(struct io_kiocb *req)
 {
-       struct io_kiocb *nxt = NULL;
+       struct io_kiocb *nxt = io_req_find_next(req);
 
-       io_req_find_next(req, &nxt);
        if (nxt)
                io_req_task_queue(nxt);
 }
@@ -1770,13 +1769,15 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req)
  * Drop reference to request, return next in chain (if there is one) if this
  * was the last reference to this request.
  */
-__attribute__((nonnull))
-static void io_put_req_find_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
+static struct io_kiocb *io_put_req_find_next(struct io_kiocb *req)
 {
+       struct io_kiocb *nxt = NULL;
+
        if (refcount_dec_and_test(&req->refs)) {
-               io_req_find_next(req, nxtptr);
+               nxt = io_req_find_next(req);
                __io_free_req(req);
        }
+       return nxt;
 }
 
 static void io_put_req(struct io_kiocb *req)
@@ -1797,7 +1798,7 @@ static struct io_wq_work *io_steal_work(struct io_kiocb *req)
        if (refcount_read(&req->refs) != 1)
                return NULL;
 
-       io_req_find_next(req, &nxt);
+       nxt = io_req_find_next(req);
        if (!nxt)
                return NULL;
 
@@ -4488,7 +4489,7 @@ static void io_poll_task_handler(struct io_kiocb *req, struct io_kiocb **nxt)
        hash_del(&req->hash_node);
        io_poll_complete(req, req->result, 0);
        req->flags |= REQ_F_COMP_LOCKED;
-       io_put_req_find_next(req, nxt);
+       *nxt = io_put_req_find_next(req);
        spin_unlock_irq(&ctx->completion_lock);
 
        io_cqring_ev_posted(ctx);
@@ -5938,9 +5939,8 @@ punt:
        }
 
 err:
-       nxt = NULL;
        /* drop submission reference */
-       io_put_req_find_next(req, &nxt);
+       nxt = io_put_req_find_next(req);
 
        if (linked_timeout) {
                if (!ret)