linux-kernel - Re: [PATCH] test_firmware: fix setting old custom fw path back on exit, second try

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Date:   Tue, 3 Apr 2018 13:12:55 -0700
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Ben Hutchings <ben.hutchings@...ethink.co.uk>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] test_firmware: fix setting old custom fw path back on
 exit, second try

On Tue, Apr 3, 2018 at 1:10 PM, Ben Hutchings
<ben.hutchings@...ethink.co.uk> wrote:
> On Tue, 2018-04-03 at 12:54 -0700, Luis R. Rodriguez wrote:
>> On Tue, Apr 3, 2018 at 12:48 PM, Ben Hutchings
>> > <ben.hutchings@...ethink.co.uk> wrote:
>> > Commit 65c79230576 tried to clear the custom firmware path on exit by
>> > writing a single space to the firmware_class.path parameter.  This
>> > doesn't work because nothing strips this space from the value stored
>> > and fw_get_filesystem_firmware() only ignores zero-length paths.
>> >
>> > Instead, write a null byte.
>> >
>> > Fixes: 0a8adf58475 ("test: add firmware_class loader test")
>> > Fixes: 65c79230576 ("test_firmware: fix setting old custom fw path back on exit")
>> > Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
>>
>> Thanks for the patch! Also can you re-send and address Greg and
>> linux-kernel ? There's significant changes to the firmware API on its
>> way to Linus to I think if we want to merge this it should go through
>> Greg at this point as he also merged some new changes I made to these
>> scripts.
>
> OK.

Oh and if you can then base it also on Greg's driver-core tree on the
driver-core-next branch

>> > ---
>> >  tools/testing/selftests/firmware/fw_filesystem.sh | 6 ++++--
>> >  1 file changed, 4 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/tools/testing/selftests/firmware/fw_filesystem.sh b/tools/testing/selftests/firmware/fw_filesystem.sh
>> > index f9508e1a4058..6b63b6bf2661 100755
>> > --- a/tools/testing/selftests/firmware/fw_filesystem.sh
>> > +++ b/tools/testing/selftests/firmware/fw_filesystem.sh
>> > @@ -46,9 +46,11 @@ test_finish()
>> >                 echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
>> >         fi
>> >         if [ "$OLD_FWPATH" = "" ]; then
>> > -               OLD_FWPATH=" "
>> > +               # A zero-length write won't work; write a null byte
>> > +               printf '\000' >/sys/module/firmware_class/parameters/path
>> > +       else
>> > +               echo -n "$OLD_FWPATH" >/sys/module/firmware_class/parameters/path
>>
>> Odd I am pretty sure I tested this and it worked for me. Wonder what
>> it could have been... What shell are you using? I used bash.
>
> Seems to work the same way for me whether I use bash (interactive) or
> dash (script interpreter, /bin/sh).  But there's no visual difference
> between " \n" and "\n"; that's why I used od to show a hex dump in my
> previous mail.

So odd, I'll test again with my qemu setup to verify again.

 Luis