From: Xie Yongji xieyongji@bytedance.com
[ Upstream commit cddce01160582a5f52ada3da9626c052d852ec42 ]
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 Reviewed-by: Josef Bacik josef@toxicpanda.com Link: https://lore.kernel.org/r/20210813151330.96-1-xieyongji@bytedance.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 45d2c28c8fc8..1061894a55df 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -805,6 +805,10 @@ 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); @@ -1973,15 +1977,19 @@ 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);