Re: [PATCH v3 4/4] wifi: ath12k: Connect to the QMI server belonging to the device owned by this driver

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- [High] Asymmetric node-id filtering in ath12k QMI:
  ath12k_qmi_ops_new_server()…

--

wifi: ath12k: Connect to the QMI server belonging to the device owned by this driver

This patch adds a get_qrtr_node_id() HIF callback that returns the QRTR node
id derived from the MHI controller index, and uses it in the QMI new_server
callback to skip WLFW services that live on a different node. A node id of
zero keeps the previous unfiltered behaviour.

> diff --git a/drivers/net/wireless/ath/ath12k/qmi.c b/drivers/net/wireless/ath/ath12k/qmi.c
> index 280e50a1f31d8..e1e75cc9d1441 100644
> --- a/drivers/net/wireless/ath/ath12k/qmi.c
> +++ b/drivers/net/wireless/ath/ath12k/qmi.c

[ ... ]

> @@ -3940,8 +3941,18 @@ static int ath12k_qmi_ops_new_server(struct qmi_handle *qmi_hdl,
>  	struct ath12k_qmi *qmi = container_of(qmi_hdl, struct ath12k_qmi, handle);
>  	struct ath12k_base *ab = qmi->ab;
>  	struct sockaddr_qrtr *sq = &qmi->sq;
> +	unsigned int node_id;
>  	int ret;
>  
> +	/* Identical devices advertise the same QMI services, so connect only to
> +	 * the QMI server on this device's node. A node id of 0 means the
> +	 * transport has not assigned a unique node id, so accept the server
> +	 * unfiltered.
> +	 */
> +	node_id = ath12k_hif_get_qrtr_node_id(ab);
> +	if (node_id && service->node != node_id)
> +		return 0;
> +

[Severity: High]
Should this return a negative errno instead of 0 for the foreign node?

In drivers/soc/qcom/qmi_interface.c, qmi_recv_new_server() only discards the
service record when the callback returns a negative value:

	ret = ops->new_server(qmi, svc);
	if (ret < 0)
		kfree(svc);
	else
		list_add(&svc->list_node, &qmi->lookup_results);

With the return 0 above, the other device's WLFW service stays in this
handle's lookup_results even though this device never connected to it.

The matching teardown path in the same qmi_ops table has no node id check:

drivers/net/wireless/ath/ath12k/qmi.c:ath12k_qmi_ops_del_server() {
	struct ath12k_qmi *qmi = container_of(qmi_hdl, struct ath12k_qmi, handle);
	struct ath12k_base *ab = qmi->ab;

	ath12k_dbg(ab, ATH12K_DBG_QMI, "qmi wifi fw del server\n");
	ath12k_qmi_driver_event_post(qmi, ATH12K_QMI_EVENT_SERVER_EXIT, NULL);
}

and qmi_recv_del_server() invokes it for every retained entry whose node
matches, with qmi_recv_bye() passing port == -1 to match all ports on the
dying node:

drivers/soc/qcom/qmi_interface.c:qmi_recv_del_server() {
	list_for_each_entry_safe(svc, tmp, &qmi->lookup_results, list_node) {
		if (node != -1 && svc->node != node)
			continue;
		if (port != -1 && svc->port != port)
			continue;

		if (ops->del_server)
			ops->del_server(qmi, svc);
	...
}

net/qrtr/ns.c:server_del() notifies every lookup matching service/instance
regardless of node, so device A's handle does receive DEL_SERVER or BYE for
device B's node when device B's firmware crashes or that card is unbound or
hot-removed.

Can that spuriously fault the healthy device? The event worker reacts to
SERVER_EXIT unconditionally:

drivers/net/wireless/ath/ath12k/qmi.c:ath12k_qmi_driver_event_work() {
	...
		case ATH12K_QMI_EVENT_SERVER_EXIT:
			set_bit(ATH12K_FLAG_CRASH_FLUSH, &ab->dev_flags);
	...
}

ATH12K_FLAG_CRASH_FLUSH makes CE sends, WMI sends, data TX
(ath12k_wifi7_dp_tx()) and mgmt TX return -ESHUTDOWN, and it makes
ath12k_core_stop() skip ath12k_dp_reoq_lut_addr_reset() and
ath12k_qmi_firmware_stop() on a device whose firmware is still running:

drivers/net/wireless/ath/ath12k/core.c:ath12k_core_stop() {
	if (!test_bit(ATH12K_FLAG_CRASH_FLUSH, &ab->dev_flags)) {
		ath12k_dp_reoq_lut_addr_reset(ath12k_ab_to_dp(ab));
		ath12k_qmi_firmware_stop(ab);
	}
	...
}

The flag is only cleared on a later FW_READY event or on core reconfigure,
so the untouched device can stay in this state indefinitely.

Would returning a negative errno here (so the foreign service is never
tracked), and/or adding the same service->node check to
ath12k_qmi_ops_del_server(), cover the teardown direction as well?

There is a second effect from the retained entries: each filtered
NEW_SERVER adds another node of the foreign device into lookup_results,
so a foreign device in a firmware restart loop accumulates duplicate
entries that each later produce their own SERVER_EXIT post.

-- 
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260922-qrtr-multi-ep-v3-0-c00831e88957%40oss.qualcomm.com