linux-kernel - Re: [PATCH] selftests: add sleep between detach and usbip list -l

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Date:   Mon, 6 May 2019 09:18:00 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Greg KH <greg@...ah.com>
Cc:     valentina.manea.m@...il.com, shuah@...nel.org,
        linux-usb@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] selftests: add sleep between detach and usbip list -l

On 5/6/19 9:15 AM, Greg KH wrote:
> On Mon, May 06, 2019 at 08:47:15AM -0600, Shuah Khan wrote:
>> On 5/5/19 3:13 AM, Greg KH wrote:
>>> On Thu, May 02, 2019 at 01:47:40PM -0600, Shuah Khan wrote:
>>>> Add a sleep between detach and check for exportable devices to avoid
>>>> the following segfault from libc-2.27.so
>>>>
>>>> [ 6268.136108] usbip[5565]: segfault at 0 ip 00007f2a947bddfd sp 00007ffd1a8705e8 error 4 in libc-2.27.so[7f2a94703000+1e7000]
>>>>
>>>> Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
>>>> ---
>>>>    tools/testing/selftests/drivers/usb/usbip/usbip_test.sh | 4 ++++
>>>>    1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/tools/testing/selftests/drivers/usb/usbip/usbip_test.sh b/tools/testing/selftests/drivers/usb/usbip/usbip_test.sh
>>>> index 128f0ab24307..beacf24a8df7 100755
>>>> --- a/tools/testing/selftests/drivers/usb/usbip/usbip_test.sh
>>>> +++ b/tools/testing/selftests/drivers/usb/usbip/usbip_test.sh
>>>> @@ -171,10 +171,14 @@ echo "Detach invalid port tests - expect invalid port error message";
>>>>    src/usbip detach -p 100;
>>>>    echo "=============================================================="
>>>> +# let detach complete. Avoid segfaults from libc-2.27.so
>>>> +sleep 3;
>>>
>>> That feels very "arbitrary", why do we "know" it will take at most 3
>>> seconds?  I guess there's not much else we can do here except maybe
>>> somehow watch sysfs until the device is really gone?
>>>
>>
>> Yeah. Number 3 is somewhat arbitrary. It helps the host process the
>> detach request from the client and update the sysfs. Detach returns
>> as soon as client side is done, and the test is running the next
>> command on the host side. If I were run these commands manually, it
>> gives enough settling time. I am looking for a quick way to allow
>> settling time in this automated test.
> 
> Ok, you might want to document that you know it's a random number :)
> 

Okay. Will do. I will send v2. :)

thanks,
-- Shuah