linux-kernel - Re: [PATCH 4.4 085/134] test_firmware: fix setting old custom fw path back on exit

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Date:   Sun, 01 Apr 2018 19:56:55 +0100
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     stable@...r.kernel.org,
        Sasha Levin <alexander.levin@...rosoft.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.4 085/134] test_firmware: fix setting old custom fw
 path back on exit

On Mon, 2018-03-19 at 19:06 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: "Luis R. Rodriguez" <mcgrof@...nel.org>
> 
> 
> [ Upstream commit 65c79230576873b312c3599479c1e42355c9f349 ]
> 
> The file /sys/module/firmware_class/parameters/path can be used
> to set a custom firmware path. The fw_filesystem.sh script creates
> a temporary directory to add a test firmware file to be used during
> testing, in order for this to work it uses the custom path syfs file
> and it was supposed to reset back the file on execution exit. The
> script failed to do this due to a typo, it was using OLD_PATH instead
> of OLD_FWPATH, since its inception since v3.17.
> 
> Its not as easy to just keep the old setting, it turns out that
> resetting an empty setting won't actually do what we want, we need
> to check if it was empty and set an empty space.

That doesn't seem to work either.  I don't see any stripping of spaces
in the generic parameter code or firmware_class, and the parameter
reads back as a space:

# echo -n ' ' > path
# od -tx1 path
0000000 20 0a
0000002

However, this seems to work:

# printf '\0' > path 
# od -tx1 path
0000000 0a
0000001

Ben.

> Without this we end up having the temporary path always set after
> we run these tests.
> 
> Fixes: 0a8adf58475 ("test: add firmware_class loader test")
> Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  tools/testing/selftests/firmware/fw_filesystem.sh |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> --- a/tools/testing/selftests/firmware/fw_filesystem.sh
> +++ b/tools/testing/selftests/firmware/fw_filesystem.sh
> @@ -28,7 +28,10 @@ test_finish()
>  	if [ "$HAS_FW_LOADER_USER_HELPER" = "yes" ]; then
>  		echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
>  	fi
> -	echo -n "$OLD_PATH" >/sys/module/firmware_class/parameters/path
> +	if [ "$OLD_FWPATH" = "" ]; then
> +		OLD_FWPATH=" "
> +	fi
> +	echo -n "$OLD_FWPATH" >/sys/module/firmware_class/parameters/path
>  	rm -f "$FW"
>  	rmdir "$FWPATH"
>  }
> 
> 
> 
-- 
Ben Hutchings
Software Developer, Codethink Ltd.