[PATCH v3 net-next] rndis_host: Flag RNDIS modems as WWAN devices

[PATCH v3 net-next] rndis_host: Flag RNDIS modems as WWAN devices

[Lubomir Rintel]

Set FLAG_WWAN instead of FLAG_ETHERNET for RNDIS interfaces on Mobile
Broadband Modems, as opposed to regular Ethernet adapters.

Otherwise NetworkManager gets confused, misjudges the device type,
and wouldn't know it should connect a modem to get the device to work.
What would be the result depends on ModemManager version -- older
ModemManager would end up disconnecting a device after an unsuccessful
probe attempt (if it connected without needing to unlock a SIM), while
a newer one might spawn a separate PPP connection over a tty interface
instead, resulting in a general confusion and no end of chaos.

The only way to get this work reliably is to fix the device type
and have good enough version ModemManager (or equivalent).

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Fixes: 63ba395cd7a5 ("rndis_host: support Novatel Verizon USB730L")

---
Changes since v1:
* Added Fixes tag, as suggested by Paolo Abeni

Changes since v2:
* Fixed Fixes tag... Suggested by Jakub Kicinski

---
 drivers/net/usb/rndis_host.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c
index 7b3739b29c8f7..bb0bf14158727 100644
--- a/drivers/net/usb/rndis_host.c
+++ b/drivers/net/usb/rndis_host.c
@@ -630,6 +630,16 @@ static const struct driver_info	zte_rndis_info = {
 	.tx_fixup =	rndis_tx_fixup,
 };
 
+static const struct driver_info	wwan_rndis_info = {
+	.description =	"Mobile Broadband RNDIS device",
+	.flags =	FLAG_WWAN | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
+	.bind =		rndis_bind,
+	.unbind =	rndis_unbind,
+	.status =	rndis_status,
+	.rx_fixup =	rndis_rx_fixup,
+	.tx_fixup =	rndis_tx_fixup,
+};
+
 /*-------------------------------------------------------------------------*/
 
 static const struct usb_device_id	products [] = {
@@ -666,9 +676,11 @@ static const struct usb_device_id	products [] = {
 	USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
 	.driver_info = (unsigned long) &rndis_info,
 }, {
-	/* Novatel Verizon USB730L */
+	/* Mobile Broadband Modem, seen in Novatel Verizon USB730L and
+	 * Telit FN990A (RNDIS)
+	 */
 	USB_INTERFACE_INFO(USB_CLASS_MISC, 4, 1),
-	.driver_info = (unsigned long) &rndis_info,
+	.driver_info = (unsigned long)&wwan_rndis_info,
 },
 	{ },		// END
 };
-- 
2.48.1

Re: [PATCH v3 net-next] rndis_host: Flag RNDIS modems as WWAN devices

[Greg KH]

On Tue, Mar 25, 2025 at 10:58:41AM +0100, Lubomir Rintel wrote:
> Set FLAG_WWAN instead of FLAG_ETHERNET for RNDIS interfaces on Mobile
> Broadband Modems, as opposed to regular Ethernet adapters.
> 
> Otherwise NetworkManager gets confused, misjudges the device type,
> and wouldn't know it should connect a modem to get the device to work.
> What would be the result depends on ModemManager version -- older
> ModemManager would end up disconnecting a device after an unsuccessful
> probe attempt (if it connected without needing to unlock a SIM), while
> a newer one might spawn a separate PPP connection over a tty interface
> instead, resulting in a general confusion and no end of chaos.
> 
> The only way to get this work reliably is to fix the device type
> and have good enough version ModemManager (or equivalent).
> 
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> Fixes: 63ba395cd7a5 ("rndis_host: support Novatel Verizon USB730L")
> 
> ---
> Changes since v1:
> * Added Fixes tag, as suggested by Paolo Abeni
> 
> Changes since v2:
> * Fixed Fixes tag... Suggested by Jakub Kicinski
> 
> ---
>  drivers/net/usb/rndis_host.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c
> index 7b3739b29c8f7..bb0bf14158727 100644
> --- a/drivers/net/usb/rndis_host.c
> +++ b/drivers/net/usb/rndis_host.c
> @@ -630,6 +630,16 @@ static const struct driver_info	zte_rndis_info = {
>  	.tx_fixup =	rndis_tx_fixup,
>  };
>  
> +static const struct driver_info	wwan_rndis_info = {
> +	.description =	"Mobile Broadband RNDIS device",
> +	.flags =	FLAG_WWAN | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
> +	.bind =		rndis_bind,
> +	.unbind =	rndis_unbind,
> +	.status =	rndis_status,
> +	.rx_fixup =	rndis_rx_fixup,
> +	.tx_fixup =	rndis_tx_fixup,
> +};
> +
>  /*-------------------------------------------------------------------------*/
>  
>  static const struct usb_device_id	products [] = {
> @@ -666,9 +676,11 @@ static const struct usb_device_id	products [] = {
>  	USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
>  	.driver_info = (unsigned long) &rndis_info,
>  }, {
> -	/* Novatel Verizon USB730L */
> +	/* Mobile Broadband Modem, seen in Novatel Verizon USB730L and
> +	 * Telit FN990A (RNDIS)
> +	 */
>  	USB_INTERFACE_INFO(USB_CLASS_MISC, 4, 1),
> -	.driver_info = (unsigned long) &rndis_info,
> +	.driver_info = (unsigned long)&wwan_rndis_info,
>  },
>  	{ },		// END
>  };
> -- 
> 2.48.1
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH v3 net-next] rndis_host: Flag RNDIS modems as WWAN devices

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 25 Mar 2025 10:58:41 +0100 you wrote:
> Set FLAG_WWAN instead of FLAG_ETHERNET for RNDIS interfaces on Mobile
> Broadband Modems, as opposed to regular Ethernet adapters.
> 
> Otherwise NetworkManager gets confused, misjudges the device type,
> and wouldn't know it should connect a modem to get the device to work.
> What would be the result depends on ModemManager version -- older
> ModemManager would end up disconnecting a device after an unsuccessful
> probe attempt (if it connected without needing to unlock a SIM), while
> a newer one might spawn a separate PPP connection over a tty interface
> instead, resulting in a general confusion and no end of chaos.
> 
> [...]

Here is the summary with links:
  - [v3,net-next] rndis_host: Flag RNDIS modems as WWAN devices
    https://git.kernel.org/netdev/net/c/67d1a8956d2d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v3 net-next] rndis_host: Flag RNDIS modems as WWAN devices

[Michał Pecio]

On Tue, 25 Mar 2025 10:58:41 +0100, Lubomir Rintel wrote:
> Set FLAG_WWAN instead of FLAG_ETHERNET for RNDIS interfaces on Mobile
> Broadband Modems, as opposed to regular Ethernet adapters.
> 
> Otherwise NetworkManager gets confused, misjudges the device type,
> and wouldn't know it should connect a modem to get the device to work.
> What would be the result depends on ModemManager version -- older
> ModemManager would end up disconnecting a device after an unsuccessful
> probe attempt (if it connected without needing to unlock a SIM), while
> a newer one might spawn a separate PPP connection over a tty interface
> instead, resulting in a general confusion and no end of chaos.
> 
> The only way to get this work reliably is to fix the device type
> and have good enough version ModemManager (or equivalent).
> 
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> Fixes: 63ba395cd7a5 ("rndis_host: support Novatel Verizon USB730L")

Hi,

This patch appears to have caused a regression for some users,
who opened a bug against the USB subsystem here:

https://bugzilla.kernel.org/show_bug.cgi?id=220002

Regards,
Michal

Re: [PATCH v3 net-next] rndis_host: Flag RNDIS modems as WWAN devices

[Lars Melin]

On 2025-04-12 05:42, Michał Pecio wrote:
> On Tue, 25 Mar 2025 10:58:41 +0100, Lubomir Rintel wrote:
>> Set FLAG_WWAN instead of FLAG_ETHERNET for RNDIS interfaces on Mobile
>> Broadband Modems, as opposed to regular Ethernet adapters.
>>
>> Otherwise NetworkManager gets confused, misjudges the device type,
>> and wouldn't know it should connect a modem to get the device to work.
>> What would be the result depends on ModemManager version -- older
>> ModemManager would end up disconnecting a device after an unsuccessful
>> probe attempt (if it connected without needing to unlock a SIM), while
>> a newer one might spawn a separate PPP connection over a tty interface
>> instead, resulting in a general confusion and no end of chaos.
>>
>> The only way to get this work reliably is to fix the device type
>> and have good enough version ModemManager (or equivalent).
>>
>> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
>> Fixes: 63ba395cd7a5 ("rndis_host: support Novatel Verizon USB730L")
> 
> Hi,
> 
> This patch appears to have caused a regression for some users,
> who opened a bug against the USB subsystem here:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=220002
> 
> Regards,
> Michal
> 

Hi,
the problem seems to be that the patch matches devices by their 
class/subclass/proto attributes assuming that all rndis devices matching 
those are rndis usb modems but it also catches rndis tethering with 
phones/tablets.
Better is to match by vid:pid as is done in the cdc_ether driver to flag 
ethernet interfaced modems to become wwan devices.

Lars