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

[Lingbo Kong]

On 2025/4/11 18:05, Lorenzo Stoakes wrote:
> +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 at 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
> 

hi, lorenzo,
sry for delay response.😊
as for as i know, this patch hasn't been accepted so far.
for your description, you find the ath12k_mac_remove_link_interface() 
have a null pointer deref, i think maybe there is a concurrent scan 
operation.

i have a suggestion, you can apply this patch and observe if there is 
still a crash.

can you offer a detailed crash dump?

/lingbo


>> ---
>> 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
>>
>>