Re: [PATCH 1/1] io_uring: break iopolling on signal

[Jens Axboe <axboe@kernel.dk>]

On 8/9/23 9:20 AM, Pavel Begunkov wrote:
> Don't keep spinning iopoll with a signal set. It'll eventually return
> back, e.g. by virtue of need_resched(), but it's not a nice user
> experience.

I wonder if we shouldn't clean it up a bit while at it, the ret clearing
is kind of odd and only used in that one loop? Makes the break
conditions easier to read too, and makes it clear that we're returning
0/-error rather than zero-or-positive/-error as well.

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 8681bde70716..ec575f663a82 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1637,7 +1637,6 @@ static __cold void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
 static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 {
 	unsigned int nr_events = 0;
-	int ret = 0;
 	unsigned long check_cq;
 
 	if (!io_allowed_run_tw(ctx))
@@ -1663,6 +1662,8 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 		return 0;
 
 	do {
+		int ret = 0;
+
 		/*
 		 * If a submit got punted to a workqueue, we can have the
 		 * application entering polling for a command before it gets
@@ -1692,12 +1693,16 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 		}
 		ret = io_do_iopoll(ctx, !min);
 		if (ret < 0)
-			break;
+			return ret;
 		nr_events += ret;
-		ret = 0;
-	} while (nr_events < min && !need_resched());
 
-	return ret;
+		if (task_sigpending(current))
+			return -EINTR;
+		if (need_resched())
+			break;
+	} while (nr_events < min);
+
+	return 0;
 }
 
 void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts)

-- 
Jens Axboe