From 2ccc92f4effcfa1c51c4fcf1e34d769099d3cad4 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed, 23 Nov 2022 11:33:36 +0000
Subject: [PATCH] io_uring: add completion locking for iopoll
There are pieces of code that may allow iopoll to race filling cqes,
temporarily add spinlocking around posting events.
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/84d86b5c117feda075471c5c9e65208e0dccf5d0.1669203009.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/rw.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 1ce065709724..61c326831949 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -1049,6 +1049,7 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
else if (!pos)
return 0;
+ spin_lock(&ctx->completion_lock);
prev = start;
wq_list_for_each_resume(pos, prev) {
struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
@@ -1063,11 +1064,11 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
req->cqe.flags = io_put_kbuf(req, 0);
__io_fill_cqe_req(req->ctx, req);
}
-
+ io_commit_cqring(ctx);
+ spin_unlock(&ctx->completion_lock);
if (unlikely(!nr_events))
return 0;
- io_commit_cqring(ctx);
io_cqring_ev_posted_iopoll(ctx);
pos = start ? start->next : ctx->iopoll_list.first;
wq_list_cut(&ctx->iopoll_list, prev, start);