linux-kernel - Re: [PATCH v2] staging: rtl8712: Fix CamelCase warnings

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Date:   Tue, 22 Mar 2022 20:29:01 +0530
From:   Sathish Kumar <skumark1902@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc:     Larry.Finger@...inger.net, florian.c.schilhabel@...glemail.com,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: rtl8712: Fix CamelCase warnings

On 22/03/22 5:01 pm, Greg KH wrote:
> On Tue, Mar 22, 2022 at 11:42:21AM +0100, Fabio M. De Francesco wrote:
>> On martedì 22 marzo 2022 05:30:29 CET Sathish Kumar wrote:
>>> On 18/03/22 4:58 pm, Greg KH wrote:
>>>> On Fri, Mar 18, 2022 at 03:44:40PM +0530, Sathish Kumar wrote:
>>>>> This patch fixes the checkpatch.pl warnings like:
>>>>> CHECK: Avoid CamelCase: <blnEnableRxFF0Filter>
>>>>> +   u8 blnEnableRxFF0Filter;
>>>>>
>>>>> Signed-off-by: Sathish Kumar <skumark1902@...il.com>
>>>>> ---
>>>>> Changes in v2:
>>>>>       - Remove the "bln" prefix
>>>>> ---
>>>>>    drivers/staging/rtl8712/drv_types.h   | 2 +-
>>>>>    drivers/staging/rtl8712/rtl871x_cmd.c | 2 +-
>>>>>    drivers/staging/rtl8712/xmit_linux.c  | 4 ++--
>>>>>    3 files changed, 4 insertions(+), 4 deletions(-)
>>>>>
>>>>> [...]
>>>>>
>>>>>    	do {
>>>>>    		msleep(100);
>>>>> -	} while (adapter->blnEnableRxFF0Filter == 1);
>>>>> +	} while (adapter->enable_rx_ff0_filter == 1);
>>>> Ah, that's funny.  It's amazing it works at all and that the compiler
>>>> doesn't optimize this away.  This isn't a good pattern to use in kernel
>>> Do you mean the following code is not a good pattern in kernel?
>>> do {
>>> msleep();
>>> } while(condition);
>> Exactly, this is not a pattern that works as you expect :)
>>
>> I was waiting for Greg to detail something more about this subject but,
>> since it looks like he has no time yet to respond, I'll try to interpret
>> his words.
>>
>> (@Greg, please forgive me if I saying something different from what you
>> intended to convey :)).
>>
>> The reason why this pattern does not work as expected is too long to be
>> explained here. However, I think that Greg is suggesting to you to research
>> and use what are called "Condition variables".
> Kind of.  The problem is that "condition" here is just looking at a
> random variable.  There is no sort of assurance that the variable will
> actually change or that that compiler even has to read from memory for
> it.  It could cache the value the first time it is read and then never
> update it for the whole loop logic.
>
> Please read Documentation/memory-barriers.txt for how to fix this all up
> and do it properly.
>
> Again, it's amazing that the current code even works at all.  So maybe
> it doesn't!  :)
>
> thansks,
>
> greg k-h

Thank you Greg and Fabio for your inputs. Will check and fix this up.

Regards,

Sathish