linux-kernel - Re: [PATCH 1/2] usb/usbip: fix uninitialized variables errors

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Message-ID: <e68cb73b-14ae-8c60-7fd6-f2aec4b6bfff@linuxfoundation.org>
Date:   Fri, 4 Nov 2022 09:18:13 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     shuah@...nel.org, valentina.manea.m@...il.com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 1/2] usb/usbip: fix uninitialized variables errors

On 11/3/22 07:21, Greg KH wrote:
> On Thu, Nov 03, 2022 at 07:12:42AM -0600, Shuah Khan wrote:
>> Fix uninitialized variable errors reported by cppcheck. One example
>> below.
>>
>> usbip/stub_main.c:284:10: error: Uninitialized variables: priv.seqnum, priv.sdev, priv.urbs, priv.sgl, priv.num_urbs, priv.completed_urbs, priv.urb_status, priv.unlinking [uninitvar]
>>    return priv;
>>
>> Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
>> ---
>>   drivers/usb/usbip/stub_main.c     | 2 +-
>>   drivers/usb/usbip/stub_rx.c       | 4 ++--
>>   drivers/usb/usbip/stub_tx.c       | 4 ++--
>>   drivers/usb/usbip/usbip_event.c   | 2 +-
>>   drivers/usb/usbip/vhci_hcd.c      | 2 +-
>>   drivers/usb/usbip/vhci_rx.c       | 2 +-
>>   drivers/usb/usbip/vhci_tx.c       | 4 ++--
>>   drivers/usb/usbip/vudc_dev.c      | 2 +-
>>   drivers/usb/usbip/vudc_rx.c       | 2 +-
>>   drivers/usb/usbip/vudc_transfer.c | 4 ++--
>>   10 files changed, 14 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c
>> index e8c3131a8543..e1248b971218 100644
>> --- a/drivers/usb/usbip/stub_main.c
>> +++ b/drivers/usb/usbip/stub_main.c
>> @@ -277,7 +277,7 @@ static DRIVER_ATTR_WO(rebind);
>>   
>>   static struct stub_priv *stub_priv_pop_from_listhead(struct list_head *listhead)
>>   {
>> -	struct stub_priv *priv, *tmp;
>> +	struct stub_priv *priv = NULL, *tmp;
>>   
>>   	list_for_each_entry_safe(priv, tmp, listhead, list) {
> 
> cppcheck is wrong here, the code is fine, and setting priv to NULL does
> nothing.  If it was required, gcc would have hopefully caught it, and
> the code would have never worked :)
> 
> So are you sure all of these changes are really needed?  Last time I
> looked, cppcheck wasn't all that smart when it came to the kernel and
> threw up huge numbers of false-positives, like this one.
> 

You are right that this one is a false positive. I will take a close look at
the others in this patch.

thanks,
-- Shuah