linux-kernel - Re: [PATCH v9 16/16] staging: r8188eu: remove usb_vendor_req

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Date:   Thu, 23 Sep 2021 13:12:53 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        David Laight <david.Laight@...lab.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Martin Kaiser <martin@...ser.cx>
Subject: Re: [PATCH v9 16/16] staging: r8188eu: remove usb_vendor_req_mutex

On 9/23/21 11:47, Pavel Skripkin wrote:
> On 9/22/21 16:21, Pavel Skripkin wrote:
>> On 9/21/21 21:18, Fabio M. De Francesco wrote:
>>> From: Pavel Skripkin <paskripkin@...il.com>
>>> 
>>> This mutex was used to protect shared buffer for USB requests. Since
>>> buffer was removed in previous patch we can remove this mutex as well.
>>> 
>>> Furthermore, because it was used to serialize the calls to the Core USB
>>> API, we thoroughly tested the enabling of concurrent firing of USB requests
>>> without the mutex and found no problems of any kind in common use cases.
>>> 
>>> Co-developed-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
>>> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
>>> Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
>> 
>> Hi, Greg!
>> 
>> If all is OK with previous 15 patches, please, do not take this one, it
>>    causes problems with connection... :)
>> 
>> I don't understand what went wrong after v8, but anyway, this one should
>> not be applied for now, since it's broken
>> 
>> 
>> Thank you
>> 
>>
> 
> 
> Just to be clear: previous 15 patches _are_ tested and do not cause any
> misbehavior or bugs.
> 
> I guess, the stack buffer maybe the problem here, since it's the only
> change on this side since v8. I didn't have a chance to take a closer
> look, but I will do it on weekends, I hope :)
> 

Oh, I found the problem by just looking at the code with clear mind:

> -free_dvobj:
> -	if (status != _SUCCESS && pdvobjpriv) {
> +	if (pdvobjpriv) {
>  		usb_set_intfdata(usb_intf, NULL);
>  		kfree(pdvobjpriv);
>  		pdvobjpriv = NULL;

This if should be deleted completely, because we don't want to fail on 
every probe :)

Sorry for noise... :(

Greg, can you take first 15 patches, if they look good and then I will 
send fixed version of 16? AFAIU, you are ok with taking part of the series


Thank you


With regards,
Pavel Skripkin