linux-kernel - [PATCH 5.7 391/393] io_uring: add missing REQ_F_COMP

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Date:   Mon, 17 Aug 2020 17:17:21 +0200
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 5.7 391/393] io_uring: add missing REQ_F_COMP_LOCKED for nested requests

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

commit 9b7adba9eaec28e0e4343c96d0dbeb9578802f5f upstream.

When we traverse into failing links or timeouts, we need to ensure we
propagate the REQ_F_COMP_LOCKED flag to ensure that we correctly signal
to the completion side that we already hold the completion lock.

Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 fs/io_uring.c |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1484,12 +1484,9 @@ static void io_req_link_next(struct io_k
 /*
  * Called if REQ_F_LINK_HEAD is set, and we fail the head request
  */
-static void io_fail_links(struct io_kiocb *req)
+static void __io_fail_links(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	unsigned long flags;
-
-	spin_lock_irqsave(&ctx->completion_lock, flags);
 
 	while (!list_empty(&req->link_list)) {
 		struct io_kiocb *link = list_first_entry(&req->link_list,
@@ -1503,13 +1500,29 @@ static void io_fail_links(struct io_kioc
 			io_link_cancel_timeout(link);
 		} else {
 			io_cqring_fill_event(link, -ECANCELED);
+			link->flags |= REQ_F_COMP_LOCKED;
 			__io_double_put_req(link);
 		}
 		req->flags &= ~REQ_F_LINK_TIMEOUT;
 	}
 
 	io_commit_cqring(ctx);
-	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+}
+
+static void io_fail_links(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (!(req->flags & REQ_F_COMP_LOCKED)) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&ctx->completion_lock, flags);
+		__io_fail_links(req);
+		spin_unlock_irqrestore(&ctx->completion_lock, flags);
+	} else {
+		__io_fail_links(req);
+	}
+
 	io_cqring_ev_posted(ctx);
 }
 
@@ -4828,6 +4841,7 @@ static int io_timeout_cancel(struct io_r
 		return -EALREADY;
 
 	req_set_fail_links(req);
+	req->flags |= REQ_F_COMP_LOCKED;
 	io_cqring_fill_event(req, -ECANCELED);
 	io_put_req(req);
 	return 0;