[PATCH 10/16] io_uring: optimise io_free_batch_list()

[Pavel Begunkov <asml.silence@gmail.com>]

Delay reading the next node in io_free_batch_list(), allows the compiler
to load the value a bit later improving register spilling in some cases.
With gcc 11.1 it helped to move @task_refs variable from the stack to a
register and optimises out a couple of per request instructions.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 10112ea73e77..50312ac4537d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2280,9 +2280,10 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
 		struct io_kiocb *req = container_of(node, struct io_kiocb,
 						    comp_list);
 
-		node = req->comp_list.next;
-		if (!req_ref_put_and_test(req))
+		if (!req_ref_put_and_test(req)) {
+			node = req->comp_list.next;
 			continue;
+		}
 
 		io_queue_next(req);
 		io_dismantle_req(req);
@@ -2294,6 +2295,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
 			task_refs = 0;
 		}
 		task_refs++;
+		node = req->comp_list.next;
 		wq_stack_add_head(&req->comp_list, &ctx->submit_state.free_list);
 	} while (node);
 
-- 
2.33.0