io_uring: refactor io_cqring_wait
It's easy to make a mistake in io_cqring_wait() because for all
break/continue clauses we need to watch for prepare/finish_wait to be
used correctly. Extract all those into a new helper
io_cqring_wait_schedule(), and transforming the loop into simple series
of func calls: prepare(); check_and_schedule(); finish();
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 5b73563..dcb9e93 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7195,6 +7195,25 @@ static int io_run_task_work_sig(void)
return -EINTR;
}
+/* when returns >0, the caller should retry */
+static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
+ struct io_wait_queue *iowq,
+ signed long *timeout)
+{
+ int ret;
+
+ /* make sure we run task_work before checking for signals */
+ ret = io_run_task_work_sig();
+ if (ret || io_should_wake(iowq))
+ return ret;
+ /* let the caller flush overflows, retry */
+ if (test_bit(0, &ctx->cq_check_overflow))
+ return 1;
+
+ *timeout = schedule_timeout(*timeout);
+ return !*timeout ? -ETIME : 1;
+}
+
/*
* Wait until events become available, if we don't already have some. The
* application must reap them itself, as they reside on the shared cq ring.
@@ -7251,27 +7270,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
io_cqring_overflow_flush(ctx, false, NULL, NULL);
prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
TASK_INTERRUPTIBLE);
- /* make sure we run task_work before checking for signals */
- ret = io_run_task_work_sig();
- if (ret > 0) {
- finish_wait(&ctx->wait, &iowq.wq);
- continue;
- }
- else if (ret < 0)
- break;
- if (io_should_wake(&iowq))
- break;
- if (test_bit(0, &ctx->cq_check_overflow)) {
- finish_wait(&ctx->wait, &iowq.wq);
- continue;
- }
- timeout = schedule_timeout(timeout);
- if (timeout == 0) {
- ret = -ETIME;
- break;
- }
- } while (1);
- finish_wait(&ctx->wait, &iowq.wq);
+ ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);
+ finish_wait(&ctx->wait, &iowq.wq);
+ } while (ret > 0);
restore_saved_sigmask_unless(ret == -EINTR);
