diff mbox series

nbd: make the config put is called before the notifying the waiter

Message ID 20201014024514.112822-1-xiubli@redhat.com (mailing list archive)
State New, archived
Headers show
Series nbd: make the config put is called before the notifying the waiter | expand

Commit Message

Xiubo Li Oct. 14, 2020, 2:45 a.m. UTC 
From: Xiubo Li <xiubli@redhat.com>

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 <xiubli@redhat.com>
---
 drivers/block/nbd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Josef Bacik Oct. 14, 2020, 5:33 p.m. UTC | #1 
On 10/13/20 10:45 PM, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> 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 <xiubli@redhat.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef
Jens Axboe Oct. 14, 2020, 6:30 p.m. UTC | #2 
On 10/13/20 8:45 PM, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> 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.

Applied, thanks.
diff mbox series

Patch

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index edf8b632e3d2..f46e26c9d9b3 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -801,9 +801,9 @@  static void recv_work(struct work_struct *work)
 		if (likely(!blk_should_fake_timeout(rq->q)))
 			blk_mq_complete_request(rq);
 	}
+	nbd_config_put(nbd);
 	atomic_dec(&config->recv_threads);
 	wake_up(&config->recv_wq);
-	nbd_config_put(nbd);
 	kfree(args);
 }