From 742fd49cf811ca164489e339b862e3fb8e240a73 Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Tue, 13 Oct 2020 22:45:14 -0400 Subject: [PATCH] nbd: make the config put is called before the notifying the waiter [ Upstream commit 87aac3a80af5cbad93e63250e8a1e19095ba0d30 ] There has one race case for ceph's rbd-nbd tool. When do mapping it may fail with EBUSY from ioctl(nbd, NBD_DO_IT), but actually the nbd device has already unmaped. It dues to if just after the wake_up(), the recv_work() is scheduled out and defers calling the nbd_config_put(), though the map process has exited the "nbd->recv_task" is not cleared. Signed-off-by: Xiubo Li Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/nbd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 7c577cabb9c3..742f8160b6e2 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -787,9 +787,9 @@ static void recv_work(struct work_struct *work) blk_mq_complete_request(blk_mq_rq_from_pdu(cmd)); } + nbd_config_put(nbd); atomic_dec(&config->recv_threads); wake_up(&config->recv_wq); - nbd_config_put(nbd); kfree(args); }