linux-kernel - [PATCH 5.10 126/199] io_uring: iopoll requests should also wake task ->in

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Date:   Mon, 25 Jan 2021 19:39:08 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.10 126/199] io_uring: iopoll requests should also wake task ->in_idle state

From: Jens Axboe <axboe@...nel.dk>

commit c93cc9e16d88e0f5ea95d2d65d58a8a4dab258bc upstream.

If we're freeing/finishing iopoll requests, ensure we check if the task
is in idling in terms of cancelation. Otherwise we could end up waiting
forever in __io_uring_task_cancel() if the task has active iopoll
requests that need cancelation.

Cc: stable@...r.kernel.org # 5.9+
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/io_uring.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2167,6 +2167,8 @@ static void io_req_free_batch_finish(str
 		struct io_uring_task *tctx = rb->task->io_uring;
 
 		percpu_counter_sub(&tctx->inflight, rb->task_refs);
+		if (atomic_read(&tctx->in_idle))
+			wake_up(&tctx->wait);
 		put_task_struct_many(rb->task, rb->task_refs);
 		rb->task = NULL;
 	}
@@ -2186,6 +2188,8 @@ static void io_req_free_batch(struct req
 			struct io_uring_task *tctx = rb->task->io_uring;
 
 			percpu_counter_sub(&tctx->inflight, rb->task_refs);
+			if (atomic_read(&tctx->in_idle))
+				wake_up(&tctx->wait);
 			put_task_struct_many(rb->task, rb->task_refs);
 		}
 		rb->task = req->task;