io_uring: don't iterate cq wait fast path

Task work runners keep running until all queues tw items are exhausted.
It's also rare for defer tw to queue normal tw and vise versa. Taking it
into account, there is only a dim chance that further iterating the
io_cqring_wait() fast path will get us anything and so we can remove
the loop there.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1f9565726661266abaa5d921e97433c831759ecf.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index da9b0397f9a1340babc7bd0f54e8011b22196fa9..dfc94654e08206a58cfac72832aa123d4793fce9 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2510,18 +2510,16 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 
        if (!io_allowed_run_tw(ctx))
                return -EEXIST;
-
-       do {
-               /* always run at least 1 task work to process local work */
-               ret = io_run_task_work_ctx(ctx);
+       if (!llist_empty(&ctx->work_llist)) {
+               ret = io_run_local_work(ctx);
                if (ret < 0)
                        return ret;
-               io_cqring_overflow_flush(ctx);
-
-               /* if user messes with these they will just get an early return */
-               if (__io_cqring_events_user(ctx) >= min_events)
-                       return 0;
-       } while (ret > 0);
+       }
+       io_run_task_work();
+       io_cqring_overflow_flush(ctx);
+       /* if user messes with these they will just get an early return */
+       if (__io_cqring_events_user(ctx) >= min_events)
+               return 0;
 
        if (sig) {
 #ifdef CONFIG_COMPAT