Re: [PATCH 6/7] nvme-rdma: Add warning on state change failure at nvme_rdma_setup_ctrl

[Sagi Grimberg <sagi@grimberg.me>]

> The transition to LIVE state should not fail in case of a new controller.
> Moving to DELETING state before nvme_tcp_create_ctrl() allocates all the
> resources may leads to NULL dereference at teardown flow (e.g., IO tagset,
> admin_q, connect_q).
> 
> Signed-off-by: Israel Rukshin <israelr@mellanox.com>
> Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/nvme/host/rdma.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index c99a882..3ae3011 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -1022,8 +1022,13 @@ static int nvme_rdma_setup_ctrl(struct nvme_rdma_ctrl *ctrl, bool new)
>   
>   	changed = nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_LIVE);
>   	if (!changed) {
> -		/* state change failure is ok if we're in DELETING state */
> +		/*
> +		 * state change failure is ok if we're in DELETING state,
> +		 * unless we're during creation of a new controller to
> +		 * avoid races with teardown flow.
> +		 */
>   		WARN_ON_ONCE(ctrl->ctrl.state != NVME_CTRL_DELETING);
> +		WARN_ON_ONCE(new);
>   		ret = -EINVAL;

I still don't understand this. Why are we warning on new controller?

Are you saying that a the state change must succeed in case its
a new controller? because if its expected to not succeed in case
of a failure then there is no point of the warning.

I am missing something here..

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