Re: [PATCH ath-next] wifi: ath12k: avoid dynamic alloc when parsing wmi tb

["Nicolas Escande" <nico.escande@gmail.com>]

On Mon Mar 9, 2026 at 4:20 PM CET, Nicolas Escande wrote:
> On each WMI message received from the hardware, we alloc a temporary array
> of WMI_TAG_MAX entries of type void *. This array is then populated with
> pointers of parsed structs depending on the WMI type, and then freed. This
> alloc can fail when memory pressure in the system is high enough.
>
> Given the fact that it is scheduled in softirq with the system_bh_wq, we
> should not be able to parse more than one WMI message per CPU at any time
>
> So instead lets move to a per cpu allocated array, stored in the struct
> ath12k_base, that is reused accros calls. The ath12k_wmi_tlv_parse_alloc()
> is also renamed into / merged with ath12k_wmi_tlv_parse() as it no longer
> allocs memory but returns the existing per-cpu one.
>
> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00218-QCAHKSWPL_SILICONZ-1
>
> Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
> ---
> changes from RFC:
>   - rebased on ath-next 8e0ab5b9adb7
>   - converted missing call sites ath12k_wmi_obss_color_collision_event()
>     & ath12k_wmi_pdev_temperature_event()
>   - changed alloc order & cleanup path in ath12k_core_alloc() as it seems
>     it confused people

And I just realized that this part did not make it to the actual commit
but stayed in the stage area. I'll add it in the v2

>   - used sizeof(*tb) in ath12k_wmi_tlv_parse()
>
> Note I did try to move to a DEFINE_PER_CPU() allocated array but the module
> loader complained about the array size. So I stuck to the per ab alloc.