[PATCH 1/8] io_uring: fix io_fail_links() locking

[Pavel Begunkov <asml.silence@gmail.com>]

86b71d0daee05 ("io_uring: deduplicate freeing linked timeouts")
actually fixed one bug, where io_fail_links() doesn't consider
REQ_F_COMP_LOCKED, but added another -- io_cqring_fill_event()
without any locking

Return locking back there and do it right with REQ_F_COMP_LOCKED
check.

Fixes: 86b71d0daee05 ("io_uring: deduplicate freeing linked timeouts")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5928404acb17..a1ea41b7b811 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1620,6 +1620,10 @@ static struct io_kiocb *io_req_link_next(struct io_kiocb *req)
 static void io_fail_links(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
+	unsigned long flags = 0;
+
+	if (!(req->flags & REQ_F_COMP_LOCKED))
+		spin_lock_irqsave(&ctx->completion_lock, flags);
 
 	while (!list_empty(&req->link_list)) {
 		struct io_kiocb *link = list_first_entry(&req->link_list,
@@ -1634,6 +1638,8 @@ static void io_fail_links(struct io_kiocb *req)
 	}
 
 	io_commit_cqring(ctx);
+	if (!(req->flags & REQ_F_COMP_LOCKED))
+		spin_unlock_irqrestore(&ctx->completion_lock, flags);
 	io_cqring_ev_posted(ctx);
 }
 
-- 
2.24.0