Re: [PATCHv2 4/5] nvme: use return value from blk_execute_rq()

[Yuanyuan Zhong <yzhong@purestorage.com>]

On Fri, Apr 23, 2021 at 3:06 PM Keith Busch <kbusch@kernel.org> wrote:
>
> We don't have an nvme status to report if the driver's .queue_rq()
> returns an error without dispatching the requested nvme command. Use the
> return value from blk_execute_rq() for all passthrough commands so the
> caller may know their command was not successful.
>
> If the command is from the target passthrough interface and fails to
> dispatch, synthesize the response back to the host as a internal target
> error.
>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/nvme/host/core.c       | 16 ++++++++++++----
>  drivers/nvme/host/ioctl.c      |  6 +-----
>  drivers/nvme/host/nvme.h       |  2 +-
>  drivers/nvme/target/passthru.c |  8 ++++----
>  4 files changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 10bb8406e067..62af5fe7a0ce 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -972,12 +972,12 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
>                         goto out;
>         }
>
> -       blk_execute_rq(NULL, req, at_head);
> +       ret = blk_execute_rq(NULL, req, at_head);
>         if (result)
>                 *result = nvme_req(req)->result;
>         if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
>                 ret = -EINTR;
> -       else
> +       else if (nvme_req(req)->status)

Since nvme_req(req)->status is uninitialized for a command failed to dispatch,
it's valid only if ret from blk_execute_rq() is 0.