From: Xie Yongji <xieyongji@bytedance.com>
To: josef@toxicpanda.com, axboe@kernel.dk
Cc: jiangyadong@bytedance.com, linux-block@vger.kernel.org,
nbd@other.debian.org
Subject: [PATCH RESEND] nbd: Aovid double completion of a request
Date: Fri, 13 Aug 2021 23:13:30 +0800 [thread overview]
Message-ID: <20210813151330.96-1-xieyongji@bytedance.com> (raw)
There is a race between iterating over requests in
nbd_clear_que() and completing requests in recv_work(),
which can lead to double completion of a request.
To fix it, flush the recv worker before iterating over
the requests and don't abort the completed request
while iterating.
Fixes: 96d97e17828f ("nbd: clear_sock on netlink disconnect")
Reported-by: Jiang Yadong <jiangyadong@bytedance.com>
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
drivers/block/nbd.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index c38317979f74..19f5d5a8b16a 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -818,6 +818,10 @@ static bool nbd_clear_req(struct request *req, void *data, bool reserved)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
+ /* don't abort one completed request */
+ if (blk_mq_request_completed(req))
+ return true;
+
mutex_lock(&cmd->lock);
cmd->status = BLK_STS_IOERR;
mutex_unlock(&cmd->lock);
@@ -2004,15 +2008,19 @@ static void nbd_disconnect_and_put(struct nbd_device *nbd)
{
mutex_lock(&nbd->config_lock);
nbd_disconnect(nbd);
- nbd_clear_sock(nbd);
- mutex_unlock(&nbd->config_lock);
+ sock_shutdown(nbd);
/*
* Make sure recv thread has finished, so it does not drop the last
* config ref and try to destroy the workqueue from inside the work
- * queue.
+ * queue. And this also ensure that we can safely call nbd_clear_que()
+ * to cancel the inflight I/Os.
*/
if (nbd->recv_workq)
flush_workqueue(nbd->recv_workq);
+ nbd_clear_que(nbd);
+ nbd->task_setup = NULL;
+ mutex_unlock(&nbd->config_lock);
+
if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
--
2.11.0
next reply other threads:[~2021-08-13 15:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-13 15:13 Xie Yongji [this message]
2021-08-13 15:45 ` [PATCH RESEND] nbd: Aovid double completion of a request Josef Bacik
2021-08-13 15:47 ` Jens Axboe
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