[PATCH] nvme: nvme_remove should cancel the reset_work before setting the ctrl state

[Keith Busch]

On Tue, Dec 05, 2017 at 12:01:35PM -0700, Thomas Tai wrote:
> During nvme_probe, a reset_work task is queued up
> for execution. When removing the nvme during unbinding,
> the remove function set the ctrl state to NVME_CTRL_DELETING
> and then cancel the reset_work. The correct sequence should
> have been cancel the reset_work first then change the state.
> 
> Otherwise, if the reset_work happens to schedule to work,
> the NVME_CTRL_DELETING causes the reset_work function to
> fail with "failed to make controller live".

The message seems to make sense. You requested to unbind the driver
before the controller went live.
 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index a11cfd4..e2d10f9 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2534,9 +2534,9 @@ static void nvme_remove(struct pci_dev *pdev)
>  {
>  	struct nvme_dev *dev = pci_get_drvdata(pdev);
>  
> -	nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
>  
>  	cancel_work_sync(&dev->ctrl.reset_work);
> +	nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
>  	pci_set_drvdata(pdev, NULL);

The state is changed before synchronously cancelling the reset work so
that nvme_remove is guaranteed another reset can't possibly occur while
we're deleting the controller. This change provies a small window for
which that could happen, and bad things will happen if it does.