[PATCH 5.8 462/464] io_uring: add missing REQ_F_COMP_LOCKED for nested requests

From: Greg Kroah-Hartman
Date: Mon Aug 17 2020 - 15:14:38 EST


From: Jens Axboe <axboe@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


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

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1549,12 +1549,9 @@ 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,
@@ -1568,13 +1565,29 @@ 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);
}

@@ -4767,6 +4780,7 @@ 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;