linux-kernel - Re: [PATCH] cxl/mem: Clarify UAPI documentation

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Message-ID: <20210414133750.000042b1@Huawei.com>
Date:   Wed, 14 Apr 2021 13:37:50 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ben Widawsky <ben.widawsky@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <linux-acpi@...r.kernel.org>, <ira.weiny@...el.com>,
        <vishal.l.verma@...el.com>, <alison.schofield@...el.com>,
        <dan.j.williams@...el.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cxl/mem: Clarify UAPI documentation

On Tue, 13 Apr 2021 07:32:47 -0700
Ben Widawsky <ben.widawsky@...el.com> wrote:

> Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>

Sensible update.

Acked-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

> ---
>  include/uapi/linux/cxl_mem.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
> index f6e8a005b113..8dd516ddb098 100644
> --- a/include/uapi/linux/cxl_mem.h
> +++ b/include/uapi/linux/cxl_mem.h
> @@ -81,6 +81,13 @@ static const struct {
>   *  - @size_in = -1
>   *  - @size_out = 0
>   *
> + * Commands which have a variable length input likely have a minimum length.
> + * This is not enforced by the UAPI, and therefore might look like the command
> + * succeeded when sending too small of an input payload. Caution should be taken
> + * by checking the @cxl_send_command.retval for such cases. For commands with a
> + * variable length output, the caller is free to consume as little or as much as
> + * they want.
> + *
>   * See struct cxl_mem_query_commands.
>   */
>  struct cxl_command_info {