[PATCH 3/6] io_uring: remove drain prealloc checks

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

Currently io_drain_req() has two steps. The first is fast path checking
sequence numbers. The second is allocations, rechecking and actual
queuing. Further simplify it by removing the first step.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/io_uring.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 21b70ad0edc4..72ae350f4f8b 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1659,17 +1659,6 @@ static __cold void io_drain_req(struct io_kiocb *req)
 	struct io_defer_entry *de;
 	u32 seq = io_get_sequence(req);
 
-	/* Still need defer if there is pending req in defer list. */
-	spin_lock(&ctx->completion_lock);
-	if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list)) {
-		spin_unlock(&ctx->completion_lock);
-queue:
-		ctx->drain_active = false;
-		io_req_task_queue(req);
-		return;
-	}
-	spin_unlock(&ctx->completion_lock);
-
 	io_prep_async_link(req);
 	de = kmalloc(sizeof(*de), GFP_KERNEL_ACCOUNT);
 	if (!de) {
@@ -1681,7 +1670,9 @@ static __cold void io_drain_req(struct io_kiocb *req)
 	if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
 		spin_unlock(&ctx->completion_lock);
 		kfree(de);
-		goto queue;
+		ctx->drain_active = false;
+		io_req_task_queue(req);
+		return;
 	}
 
 	trace_io_uring_defer(req);
-- 
2.49.0