Re: [RFC PATCH v3] Bluetooth: l2cap: prefer compatible local LE intervals

[cochcoder]

Hi,

Following up on this patch, is there anything else needed to move it forward?

Thanks,
Kyle


On Thursday, October 15th, 2026 at 2:11 PM, Kyle Pepper <cochcoder@xxxxxxxxx> wrote:

> Use a valid intersection of a peer interval range and local preferences
> when they overlap. Otherwise retain the peer request instead of treating
> an initial preference as a hard supported bound.
> 
> Validate the original wire request first. Only narrow its interval range;
> leave latency, timeout and disjoint-range acceptance unchanged.
> 
> Assisted-by: OpenCode:gpt-6.1-sol
> Signed-off-by: Kyle Pepper <cochcoder@xxxxxxxxx>
> ---
> Changes since v2:
> - Wrap test notes to avoid the GitLint B1 failure in series 1186108.
> - Refresh onto bluetooth-next ff8b09806b7b; no source delta from v2.
> 
> Changes from v1 retained:
> - Treat local ranges as preferences, not supported bounds.
> - Prefer a valid intersection; otherwise keep the valid peer request.
> - Never repair an invalid original request by clipping.
> - Preserve latency, supervision timeout and disjoint-range acceptance.
> 
> Prior native controls check the accepted L2CAP response and HCI range:
> overlap, fast HID fallback, slow idle fallback and exact match. Baseline
> passes 3/4; strict bounds pass 2/4 (reject HID/idle); v2 passes 4/4.
> The prior reference-guest full L2CAP suite passes 115/115, without skips
> or captured KASAN/lockdep alerts. These are prior runs, not fresh v3 VMs.
> 
> The independent BlueZ test companion was sent as:
> https://lore.kernel.org/r/20261015044221.55631-1-cochcoder@xxxxxxxxx
> Its overlap case intentionally fails without this kernel change.
> Completed-interval startup/stream gating remains separate profile work.
> 
> The saved v2 CI report lists all jobs except GitLint passing, including
> the native L2CAP tester. This is not a remote CI result for v3.
> The combined Arch trial is reported working on hardware, not isolated
> testing of bluetooth-next or exhaustive device/negative-path coverage.
> 
>  net/bluetooth/l2cap_core.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 4dd56e007..afde04a19 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -5031,6 +5031,19 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
>  	memset(&rsp, 0, sizeof(rsp));
>  
>  	err = hci_check_conn_params(min, max, latency, to_multiplier);
> +	if (!err) {
> +		u16 pref_min = max_t(u16, min, hcon->le_conn_min_interval);
> +		u16 pref_max = min_t(u16, max, hcon->le_conn_max_interval);
> +
> +		/* Local preferences must not reject a valid peer request. */
> +		if (pref_min <= pref_max &&
> +		    !hci_check_conn_params(pref_min, pref_max, latency,
> +					  to_multiplier)) {
> +			min = pref_min;
> +			max = pref_max;
> +		}
> +	}
> +
>  	if (err)
>  		rsp.result = cpu_to_le16(L2CAP_CONN_PARAM_REJECTED);
>  	else
> 
> base-commit: ff8b09806b7b18884ad8d3a2b3d702da534a4e21
>