Re: [PATCH v3] wifi: ath12k: fix survey indexing across bands

[Jeff Johnson]

On 7/3/2026 8:56 AM, Matthew Leach wrote:
> When running 'iw dev wlan0 survey dump' the values for the channel busy
> time have the same sequence across bands. This is caused by indexing
> into the ath12k survey array using a band-local index rather than the
> global index passed by mac80211. This results in surveys for 5 GHz and 6
> GHz channels returning values from 2.4 GHz slots, making the survey
> unusable on those bands. Further, there are redundant survey slots for
> multi-radio/single-phy instances.
> 
> Fix by moving the survey data into ath12k_hw so multiple radios under a
> single wiphy share one table, and index into it using the global
> mac80211 index. A new spinlock in ath12k_hw serialises access to the
> survey array, which is now shared across all radios under a single hw.
> 
> Band busy-times Before this fix:
> 
> 2.4 GHz: 9, 2, 2, 2, 4, 2, 10, 16, 4, 12, 5
> 5 GHz:   9, 2, 2, 2, 4, 2, 10, 16, 4, 12, 5
> 6 GHz:   9, 2, 2, 2, 4, 2, 10, 16, 4, 12, 5
> 
> After this fix, times are independent:
> 
> 2.4 GHz: 23, 5,  5,  12, 2,   12,  26,  5,   3,  1,  27
> 5 GHz:   30, 40, 29, 27, 118, 118, 112, 120, 11, 11, 11
> 6 GHz:   1,  0,  0,  0,  0,   0,   0,   0,   0,  0,  1
> 
> Tested-on: wcn7850 hw2.0 PCI WLAN.IOE_HMT.1.1-00018-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1
> 
> Fixes: 4f242b1d6996 ("wifi: ath12k: support get_survey mac op for single wiphy")
> Signed-off-by: Matthew Leach <matthew.leach@xxxxxxxxxxxxx>
> ---

my review agent flagged:
"file": "drivers/net/wireless/ath/ath12k/core.h",
"summary": "data_lock comment still lists 'survey info' as one of the fields
it protects, but survey data is now protected by ah->survey_lock",
"failure_scenario": "A developer adding survey-related code follows the
comment and uses data_lock to protect ah->survey[], introducing an unprotected
access (since the actual readers/writers use survey_lock, not data_lock)."

I'll update the comment in my pending branch

/jeff