linux-kernel - Re: [PATCH] staging: qlge: replace msleep with usleep

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Date:   Fri, 1 Jul 2022 10:01:13 -0700
From:   Arun Vijayshankar <arunvijayshankar@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org,
        linux-staging@...ts.linux.dev, netdev@...r.kernel.org
Cc:     manishc@...vell.com, GR-Linux-NIC-Dev@...vell.com
Subject: Re: [PATCH] staging: qlge: replace msleep with usleep_range

On Mon, Jun 27, 2022 at 08:12:38AM +0200, Greg KH wrote:
>> On Sun, Jun 26, 2022 at 09:53:33PM -0700, Arun Vijayshankar wrote:
>>> qlge_close uses msleep for 1ms, in which case (1 - 20ms) it is preferable
>>> to use usleep_range in non-atomic contexts, as documented in
>>> Documentation/timers/timers-howto.rst. A range of 1 - 1.05ms is
>>> specified here, in case the device takes slightly longer than 1ms to recover from
>>> reset.
>>>
>>> Signed-off-by: Arun Vijayshankar <arunvijayshankar@...il.com>
>>> ---
>>>  drivers/staging/qlge/qlge_main.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/staging/qlge/qlge_main.c b/drivers/staging/qlge/qlge_main.c
>>> index 689a87d58f27..3cc4f1902c80 100644
>>> --- a/drivers/staging/qlge/qlge_main.c
>>> +++ b/drivers/staging/qlge/qlge_main.c
>>> @@ -3886,7 +3886,7 @@ static int qlge_close(struct net_device *ndev)
>>>  	 * (Rarely happens, but possible.)
>>>  	 */
>>>  	while (!test_bit(QL_ADAPTER_UP, &qdev->flags))
>>> -		msleep(1);
>>> +		usleep_range(1000, 1050);
>> Have you tested this with a device?  Doing these types of changes
>> without access to the hardware isn't a good idea.
>>
>> Also, a loop that has the chance to never end should be fixed up, don't
>> you think?
>>
>> thanks,
>>
>> greg k-h
> I have not tested the change with the hardware. I have checked that the module loads on my PC, but I do not have the actual adapter
> to test it out. Would you mind sharing any pointers on testing changes on the actual device if I don't have the specific device?
> I tried to find an emulator or virtual device for the QL adapter, but there doesn't seem to be any. Sorry if this is a very basic 
> question. This is my first patch ever. If there isn't a good way to test the changes with hardware, would you recommend withdrawing it?
>
> Thanks for pointing out the potential runaway loop. I'm a little embarrased on having missed it. I can add a timeout if the device doesn't 
> recover within a given time, but I was wondering if there is a better way of doing it?
>
> Best regards
> Arun Vijayshankar