Re: [PATCH ath-next v2] wifi: ath12k: Abort scan before removing link interface to prevent duplicate deletion

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

+cc Oleskandr who kindly pointed me at the v1 of this patch (see [0]).

[0]:https://lore.kernel.org/all/20250124093352.481-1-quic_lingbok@quicinc.com/

On Wed, Feb 26, 2025 at 07:31:18PM +0800, Lingbo Kong wrote:
> Currently, when ath12k performs the remove link interface operation, if
> there is an ongoing scan operation on the arvif, ath12k may execute the
> remove link interface operation multiple times on the same arvif. This
> occurs because, during the remove link operation, if a scan operation is
> present on the arvif, ath12k may receive a WMI_SCAN_EVENT_COMPLETED event
> from the firmware. Upon receiving this event, ath12k will continue to
> execute the ath12k_scan_vdev_clean_work() function, performing the remove
> link interface operation on the same arvif again.
>
> To address this issue, before executing the remove link interface
> operation, ath12k needs to check if there is an ongoing scan operation on
> the current arvif. If such an operation exists, it should be aborted.
>
> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
>
> Signed-off-by: Lingbo Kong <quic_lingbok@quicinc.com>

Hey, thanks for this!

Not sure on status of this, has the patch been taken for 6.15? As I don't
see it in Linus's tree (not looking _that_ hard though). I don't think it's
even in -next?

I keep hitting issues with my X870E CARBON wifi onboard motherboard wifi -
most recently I saw a null pointer deref in ath12k_mac_remove_link_interface().

This occurred when I tried changing the network interface, in fact I had
first clicked on 'available networks' in network manager so quite likely a
concurrent scan.

I rather stupidly didn't copy/paste the text of it, but you can see the
report in screenshot form at [1]. Apologies for shade being case on ath12k
driver but you know, frustrations :))

It's difficult for me to test your patch as I am having pretty awful
firmware issue with this motherboard - if I powercycle in any way that gets
interrupted, or especially if a kernel issue arises, then the ath12k module
will not load on next boot, or at all going forward.

Updating the kernel to, I think, a recent 6.13 (and now 6.14-1 where I
observed this issue), got the wifi working again, seemingly randomly.

Usually I have to try to reset the CMOS state, but doing so causes other
issues so I generally try to avoid (I have a network workaround involving
an ethernet wifi adapater, it's pretty... yeah).

So I assume some non-volatile state gets corrupted somehow, I'm not sure if
you had any insights into how I might more sanely reset that?

Anyway regardless thanks for your efforts, if the wifi adapter appears
again then I will test this and can give T-b tags if so.

Cheers, Lorenzo

[1]:https://fosstodon.org/@ljs/114318530969496869

> ---
> 1.rebase to ath-next
>
>  drivers/net/wireless/ath/ath12k/mac.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
> index 3e3afdc56fc9..551133483f44 100644
> --- a/drivers/net/wireless/ath/ath12k/mac.c
> +++ b/drivers/net/wireless/ath/ath12k/mac.c
> @@ -9578,6 +9578,11 @@ ath12k_mac_op_unassign_vif_chanctx(struct ieee80211_hw *hw,
>  	if (ahvif->vdev_type != WMI_VDEV_TYPE_MONITOR &&
>  	    ar->num_started_vdevs == 1 && ar->monitor_vdev_created)
>  		ath12k_mac_monitor_stop(ar);
> +
> +	if (ar->scan.arvif == arvif && ar->scan.state == ATH12K_SCAN_RUNNING) {
> +		ath12k_scan_abort(ar);
> +		ar->scan.arvif = NULL;
> +	}
>  }
>
>  static int
>
> base-commit: e180a01bf2c4a67db13d70d2d91410a8c6f74be3
> --
> 2.34.1
>
>