linux-kernel - Re: [PATCH] Documentation: firmware: Clarify firmware path usage

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Date:   Mon, 10 Apr 2023 16:43:05 -0600
From:   Jonathan Corbet <corbet@....net>
To:     Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org,
        Florian Fainelli <f.fainelli@...il.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH] Documentation: firmware: Clarify firmware path usage

Florian Fainelli <f.fainelli@...il.com> writes:

> Newline characters will be taken into account for the firmware search
> path parameter, warn users about that and provide an example using 'echo
> -n' such that it clarifies the typical use of that parameter.
>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  Documentation/driver-api/firmware/fw_search_path.rst | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/driver-api/firmware/fw_search_path.rst b/Documentation/driver-api/firmware/fw_search_path.rst
> index a360f1009fa3..d7cb1e8f0076 100644
> --- a/Documentation/driver-api/firmware/fw_search_path.rst
> +++ b/Documentation/driver-api/firmware/fw_search_path.rst
> @@ -22,5 +22,10 @@ can use the file:
>  
>  * /sys/module/firmware_class/parameters/path
>  
> -You would echo into it your custom path and firmware requested will be
> -searched for there first.
> +You would echo into it your custom path and firmware requested will be searched
> +for there first. Be aware that newline characters will be taken into account
> +and may not produce the intended effects. For instance you might want to use:
> +
> +echo -n /path/to/script > /sys/module/firmware_class/parameters/path
> +
> +to ensure that your script is being used.

So I have no problem with applying this, but I have to ask...might it
not be better to fix the implementation of that sysfs file to strip
surrounding whitespace from the provided path?  This patch has the look
of a lesson learned the hard way; rather than codifying this behavior
into a feature, perhaps we could just make the next person's life a bit
easier...?

Thanks,

jon