Re: [PATCH ath-next] wifi: ath12k: Fix the assignment of logical link index

[Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>]

On 2/26/2026 9:49 AM, Roopni Devanathan wrote:
> From: Manish Dharanenthiran <manish.dharanenthiran@oss.qualcomm.com>
> 
> Per-link logical index is assigned from the global counter,
> ahsta->num_peer. This logical index is sent to firmware during peer
> association. If there is a failure in creating a link station,
> ath12k_mac_free_unassign_link_sta() clears the link, but does not decrement
> the logical link index. This will result in a higher logical link index for
> the next link station created. Also, if there is a leak in logical link
> index as we assign the incremented num_peer, then the index can exceed the
> maximum valid value of 15.
> 
> As an example, let's say we have a 2 GHz + 5 GHz + 6 GHz MLO setup. So the
> logical link indices that they have are 0, 1 and 2, respectively. If the
> 5 GHz link is removed, logical link index 1 becomes available, and num_peer
> is not reduced to 2 and still remains at 3. If a new 5 GHz link is added
> later, it gets the index 3, instead of reusing link index 1. Also,
> num_peer is increased to 4, though only 3 links are present.
> 
> To resolve these, create a bitmap, free_logical_link_idx, that tracks the
> available logical link indices. When a link station is created, select the
> first free logical index and when a link station is removed, mark its
> logical link index as available by setting the bit.
> 
> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.6-01181-QCAHKSWPL_SILICONZ-1
> 
> Signed-off-by: Manish Dharanenthiran <manish.dharanenthiran@oss.qualcomm.com>
> Signed-off-by: Roopni Devanathan <roopni.devanathan@oss.qualcomm.com>

Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>