Re: [PATCH] wifi: ath11k: fix warning when unbinding

[Jose Ignacio Tornos Martinez <jtornosm@redhat.com>]

Hello Rameshkumar,

> I agree that setting tx_status to NULL makes ath11k_dp_free() more
> defensive, and it matches the ath12k fix.
Ok, I agree too.

> However, i am still wondering how the second ath11k_dp_free() is reached 
> if ATH11K_FLAG_QMI_FAIL is set.
>
> In ath11k_pci_remove(), when ATH11K_FLAG_QMI_FAIL is set, we take the
> qmi_fail path and skip ath11k_core_deinit(). So the normal remove path:
>
>     ath11k_pci_remove()
>       ath11k_core_deinit()
>         ath11k_core_soc_destroy()
>           ath11k_dp_free()
>
> should not run.
>
> So if the double free is still reproducible with QMI_FAIL set (with the 
> change i proposed), either the flag is not actually set in this failure 
> case, or there is another path calling ath11k_dp_free() ?
Let me try to clarify the issue more.
There are two error actions:
- First the previous error. I reproduce the situation as I commented: running
in a VM the default upstream kernel (with this card using PCI passthrough),
since this is always failing. Let me show the logs in this situation:
[   15.906564] ath11k_pci 0000:07:00.0: BAR 0 [mem 0xfdc00000-0xfddfffff 64bit]: assigned
[   15.926520] ath11k_pci 0000:07:00.0: MSI vectors: 32
[   15.928572] ath11k_pci 0000:07:00.0: wcn6855 hw2.0
[   16.984192] ath11k_pci 0000:07:00.0: chip_id 0x2 chip_family 0xb board_id 0xff soc_id 0x400c0200
[   16.984351] ath11k_pci 0000:07:00.0: fw_version 0x11088c35 fw_build_timestamp 2024-04-17 08:34 fw_build_id WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
[   18.186971] ath11k_pci 0000:07:00.0: failed to receive control response completion, polling..
[   19.211036] ath11k_pci 0000:07:00.0: Service connect timeout
[   19.211815] ath11k_pci 0000:07:00.0: failed to connect to HTT: -110
[   19.214181] ath11k_pci 0000:07:00.0: failed to start core: -110
[   19.531989] ath11k_pci 0000:07:00.0: firmware crashed: MHI_CB_EE_RDDM
[   19.532930] ath11k_pci 0000:07:00.0: ignore reset dev flags 0xc000
[   29.259157] ath11k_pci 0000:07:00.0: failed to wait wlan mode request (mode 4): -110
[   29.259229] ath11k_pci 0000:07:00.0: qmi failed to send wlan mode off: -110
- Second after this, I commanded the unbinded (ath11_pci) and I get the
warning. Let extend here the stack trace:
[   24.238198]  ? free_large_kmalloc+0x57/0x90
[   24.238199]  ? report_bug+0x16b/0x180
[   24.238210]  ? handle_bug+0x3c/0x70
[   24.238218]  ? exc_invalid_op+0x14/0x70
[   24.238218]  ? asm_exc_invalid_op+0x16/0x20
[   24.238224]  ? free_large_kmalloc+0x57/0x90
[   24.238227]  ath11k_dp_free+0x99/0xb0 [ath11k]
[   24.238275]  ath11k_core_deinit+0x12b/0x1a0 [ath11k]
[   24.238287]  ath11k_pci_remove+0x7b/0x120 [ath11k_pci]
[   24.238294]  pci_device_remove+0x3e/0xb0
[   24.238304]  device_release_driver_internal+0x193/0x200
[   24.238315]  unbind_store+0x9d/0xb0
[   24.238320]  kernfs_fop_write_iter+0x13a/0x1d0
[   24.238330]  vfs_write+0x32e/0x470
[   24.238335]  ksys_write+0x5f/0xe0
[   24.238336]  do_syscall_64+0x5f/0xe0
Very easy to reproduce.

Anyway, although you can avoid a specific path, IMHO this small fix is
recommendable to avoid other similar situations.

Thanks

Best regards
José Ignacio