Re: [PATCH] Bluetooth: L2CAP: rate-limit ECHO_RSP per signaling PDU

[Luiz Augusto von Dentz]

Hi Michael,

On Mon, May 18, 2026 at 8:43 PM Michael Bommarito
<michael.bommarito@xxxxxxxxx> wrote:
>
> On Mon, May 18, 2026 at 5:37 PM Luiz Augusto von Dentz
> <luiz.dentz@xxxxxxxxx> wrote:
>
> Two questions on this:
>
> > > Implementations shall be able to handle the reception of multiple
> > > commands in an L2CAP packet sent over fixed channel CID 0x0001.
> > > [] https://www.bluetooth.com/wp-content/uploads/Files/Specification/HTML/Core-62/out/en/host/logical-link-control-and-adaptation-protocol-specification.html#UUID-32a25a06-4aa4-c6c7-77c5-dcfe3682355d
> > >
> > > Perhaps we should define our Signalling MTU:
> > >
> > > Signaling MTU (MTUsig)
> > ...
>
> I went to add the constant in l2cap.h and noticed that our const names
> don't quite align with the spec names.  Do you want me to call this
> MAX_MTU to be consistent with the const names or SIG_MTU to stick to
> the standard?

I guess L2CAP_SIG_MTU is fine.

>
> > So we need to reject with L2CAP_REJ_MTU_EXCEEDED.
>
> It looks like this would be our first use of L2CAP_REJ_MTU_EXCEEDED
> anywhere, which seemed suspicious.  Can you think of any other
> locations offhand where we might want to check for an MTU guard?

This is our first use. I don't think this error existed initially; it
was probably added to handle cases where signalling channels need to
indicate their MTU.

> Thanks,
> Mike



-- 
Luiz Augusto von Dentz