io_uring/napi: refactor __io_napi_busy_loop()

we don't need to set ->napi_prefer_busy_poll if we're not going to poll,
do the checks first and all polling preparation after.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2ad7ede8cc7905328fc62e8c3805fdb11635ae0b.1723039801.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/napi.c

@@ -299,10 +299,11 @@ void __io_napi_adjust_timeout(struct io_ring_ctx *ctx, struct io_wait_queue *iow
  */
 void __io_napi_busy_loop(struct io_ring_ctx *ctx, struct io_wait_queue *iowq)
 {
-	iowq->napi_prefer_busy_poll = READ_ONCE(ctx->napi_prefer_busy_poll);
+	if (ctx->flags & IORING_SETUP_SQPOLL)
+		return;
 
-	if (!(ctx->flags & IORING_SETUP_SQPOLL))
-		io_napi_blocking_busy_loop(ctx, iowq);
+	iowq->napi_prefer_busy_poll = READ_ONCE(ctx->napi_prefer_busy_poll);
+	io_napi_blocking_busy_loop(ctx, iowq);
 }
 
 /*