Re: issues with cdc ncm host class driver

Re: issues with cdc ncm host class driver

[Oliver Neukum]

On 03.04.23 08:14, Purohit, Kaushal wrote:
> Hi,
> 

Hi,

> Referring to patch with commit ID (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
> 
> This is a spec violation for CDC NCM class driver. Driver clearly says the significance of network capabilities. (snapshot below)
> 
> However, with the mentioned patch these values are disrespected and commands specific to these capabilities are sent from the host regardless of device' capabilities to handle them.

Right. So for your device, the correct behavior would be to do
nothing, wouldn't it? The packets would be delivered and the host
needs to filter and discard unrequested packets.

> Currently we are setting these bits to 0 indicating no capabilities on our device and still we observe that Host (Linux kernel host cdc driver) has been sending requests specific to these capabilities.
> 
> Please let me know if there is a better way to indicate host that device does not have these capabilities.

no you are doing things as they are supposed to be done and
the host is at fault. This kernel bug needs to be fixed.

	Regards
		Oliver

RE: [EXTERNAL] Re: issues with cdc ncm host class driver

[Purohit, Kaushal]

Oliver, Thanks for the quick confirmation. Tracked in kernel Bugzilla by "Bug 217290".

-----Original Message-----
From: Oliver Neukum <oneukum@suse.com> 
Sent: Monday, April 3, 2023 3:39 PM
To: Purohit, Kaushal <kaushal.purohit@ti.com>; stable@vger.kernel.org
Cc: regressions@lists.linux.dev; linux-usb@vger.kernel.org
Subject: [EXTERNAL] Re: issues with cdc ncm host class driver

On 03.04.23 08:14, Purohit, Kaushal wrote:
> Hi,
> 

Hi,

> Referring to patch with commit ID (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
> 
> This is a spec violation for CDC NCM class driver. Driver clearly says 
> the significance of network capabilities. (snapshot below)
> 
> However, with the mentioned patch these values are disrespected and commands specific to these capabilities are sent from the host regardless of device' capabilities to handle them.

Right. So for your device, the correct behavior would be to do nothing, wouldn't it? The packets would be delivered and the host needs to filter and discard unrequested packets.

> Currently we are setting these bits to 0 indicating no capabilities on our device and still we observe that Host (Linux kernel host cdc driver) has been sending requests specific to these capabilities.
> 
> Please let me know if there is a better way to indicate host that device does not have these capabilities.

no you are doing things as they are supposed to be done and the host is at fault. This kernel bug needs to be fixed.

	Regards
		Oliver

Re: issues with cdc ncm host class driver

[Linux regression tracking (Thorsten Leemhuis)]

[adding Miguel Rodríguez Pérez and Bjørn Mork from the signed-off-by
chain of the culprit to the list of recipients]

Side note: there is now a bug tracking ticket for this issue, too:
https://bugzilla.kernel.org/show_bug.cgi?id=217290

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 03.04.23 12:09, Oliver Neukum wrote:
> On 03.04.23 08:14, Purohit, Kaushal wrote:

>> Referring to patch with commit ID
>> (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
>>
>> This is a spec violation for CDC NCM class driver. Driver clearly says
>> the significance of network capabilities. (snapshot below)
>>
>> However, with the mentioned patch these values are disrespected and
>> commands specific to these capabilities are sent from the host
>> regardless of device' capabilities to handle them.
> 
> Right. So for your device, the correct behavior would be to do
> nothing, wouldn't it? The packets would be delivered and the host
> needs to filter and discard unrequested packets.
> 
>> Currently we are setting these bits to 0 indicating no capabilities on
>> our device and still we observe that Host (Linux kernel host cdc
>> driver) has been sending requests specific to these capabilities.
>>
>> Please let me know if there is a better way to indicate host that
>> device does not have these capabilities.
> 
> no you are doing things as they are supposed to be done and
> the host is at fault. This kernel bug needs to be fixed.

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced e10dcb1b6ba714243ad
https://bugzilla.kernel.org/show_bug.cgi?id=217290
#regzbot from: Purohit, Kaushal
#regzbot title net: cdc_ncm: spec violation for CDC NCM
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.

Re: issues with cdc ncm host class driver

[Oliver Neukum]

On 03.04.23 08:14, Purohit, Kaushal wrote:
> Hi,
> 
> Referring to patch with commit ID (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
> 
> This is a spec violation for CDC NCM class driver. Driver clearly says the significance of network capabilities. (snapshot below)
> 
> However, with the mentioned patch these values are disrespected and commands specific to these capabilities are sent from the host regardless of device' capabilities to handle them.
> 
> Currently we are setting these bits to 0 indicating no capabilities on our device and still we observe that Host (Linux kernel host cdc driver) has been sending requests specific to these capabilities.

Hi,

please test the patch I've attached to kernel.org's bugzilla.

	Regards
		Oliver

Re: issues with cdc ncm host class driver

[Linux regression tracking (Thorsten Leemhuis)]

On 05.04.23 12:53, Oliver Neukum wrote:
> On 03.04.23 08:14, Purohit, Kaushal wrote:
>>
>> Referring to patch with commit ID
>> (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
>>
>> This is a spec violation for CDC NCM class driver. Driver clearly says
>> the significance of network capabilities. (snapshot below)
>>
>> However, with the mentioned patch these values are disrespected and
>> commands specific to these capabilities are sent from the host
>> regardless of device' capabilities to handle them.
>>
>> Currently we are setting these bits to 0 indicating no capabilities on
>> our device and still we observe that Host (Linux kernel host cdc
>> driver) has been sending requests specific to these capabilities.
> 
> Hi,
> 
> please test the patch I've attached to kernel.org's bugzilla.

Did you ever do that? Doesn't look like it from here, but maybe I'm
missing something.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.

BTW, let me fix something up in regzbot while at it:

#regzbot from: Kaushal Purohit
#regzbot poke

Re: issues with cdc ncm host class driver

[Linux regression tracking (Thorsten Leemhuis)]

On 04.04.23 12:33, Linux regression tracking (Thorsten Leemhuis) wrote:
> Side note: there is now a bug tracking ticket for this issue, too:
> https://bugzilla.kernel.org/show_bug.cgi?id=217290
> 
> On 03.04.23 12:09, Oliver Neukum wrote:
>> On 03.04.23 08:14, Purohit, Kaushal wrote:
> 
>>> Referring to patch with commit ID
>>> (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
>>>
>>> This is a spec violation for CDC NCM class driver. Driver clearly says
>>> the significance of network capabilities. (snapshot below)
>>>
>>> However, with the mentioned patch these values are disrespected and
>>> commands specific to these capabilities are sent from the host
>>> regardless of device' capabilities to handle them.
>>
>> Right. So for your device, the correct behavior would be to do
>> nothing, wouldn't it? The packets would be delivered and the host
>> needs to filter and discard unrequested packets.
> 
> #regzbot ^introduced e10dcb1b6ba714243ad
> https://bugzilla.kernel.org/show_bug.cgi?id=217290
> #regzbot from: Purohit, Kaushal
> #regzbot title net: cdc_ncm: spec violation for CDC NCM
> #regzbot ignore-activity

Not sure what happen to this, my last inquiries were not answered, so it
seems nobody cares anymore

#regzbot inconclusive: radio silence, ignoring
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.

RE: [EXTERNAL] Re: issues with cdc ncm host class driver

[Purohit, Kaushal]

Apologies for late reply, I was stuck with something.

Yes attached patch was working well. I did not see set filter params request after applying this patch.

Thanks,
Kaushal

-----Original Message-----
From: Linux regression tracking (Thorsten Leemhuis) <regressions@leemhuis.info> 
Sent: Tuesday, June 20, 2023 7:46 PM
To: Oliver Neukum <oneukum@suse.com>; Purohit, Kaushal <kaushal.purohit@ti.com>; stable@vger.kernel.org
Cc: regressions@lists.linux.dev; linux-usb@vger.kernel.org
Subject: [EXTERNAL] Re: issues with cdc ncm host class driver

On 04.04.23 12:33, Linux regression tracking (Thorsten Leemhuis) wrote:
> Side note: there is now a bug tracking ticket for this issue, too:
> https://bugzilla.kernel.org/show_bug.cgi?id=217290
> 
> On 03.04.23 12:09, Oliver Neukum wrote:
>> On 03.04.23 08:14, Purohit, Kaushal wrote:
> 
>>> Referring to patch with commit ID
>>> (*e10dcb1b6ba714243ad5a35a11b91cc14103a9a9*).
>>>
>>> This is a spec violation for CDC NCM class driver. Driver clearly 
>>> says the significance of network capabilities. (snapshot below)
>>>
>>> However, with the mentioned patch these values are disrespected and 
>>> commands specific to these capabilities are sent from the host 
>>> regardless of device' capabilities to handle them.
>>
>> Right. So for your device, the correct behavior would be to do 
>> nothing, wouldn't it? The packets would be delivered and the host 
>> needs to filter and discard unrequested packets.
> 
> #regzbot ^introduced e10dcb1b6ba714243ad
> https://bugzilla.kernel.org/show_bug.cgi?id=217290
> #regzbot from: Purohit, Kaushal
> #regzbot title net: cdc_ncm: spec violation for CDC NCM #regzbot 
> ignore-activity

Not sure what happen to this, my last inquiries were not answered, so it seems nobody cares anymore

#regzbot inconclusive: radio silence, ignoring #regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.