Re: [PATCH ath-next 2/2] wifi: ath11k: initialise the CE descriptor waitqueue once per device

[Baochen Qiang <baochen.qiang@oss.qualcomm.com>]

On 8/6/2026 3:21 AM, Julius Bairaktaris wrote:
> ath11k_wmi_pdev_attach() runs init_waitqueue_head() on the pdev's
> tx_ce_desc_wq. It is called from ath11k_wmi_attach() ->
> ath11k_core_start(), which firmware crash recovery re-runs through
> ath11k_core_qmi_firmware_ready(), so the head is reinitialised on every
> recovery - including while a task is still queued on it.
> 
> Parts with hw_params.credit_flow clear - ipq8074, ipq6018, ipq5018,
> wcn6750 - take the else branch of ath11k_wmi_cmd_send() and sleep there
> in wait_event_timeout() for up to WMI_SEND_TIMEOUT_HZ. That is longer
> than a recovery takes, so an ordinary WMI command issued from userspace
> just before the crash is still on the queue when the head is cleared
> under it, and finish_wait() then deletes the entry from a list head that
> no longer refers to it:
> 
>   WARNING: CPU: 1 PID: 1861 at lib/list_debug.c:62 __list_del_entry_valid_or_report+0x110/0x154
>   CPU: 0 UID: 101 Comm: hostapd
>   Call trace:
>    __list_del_entry_valid_or_report+0x110/0x154 (P)
>    finish_wait+0xcc/0xd0
>    ath11k_wmi_cmd_send+0x150/0x2f4 [ath11k]
>    ath11k_wmi_vdev_set_param_cmd+0x64/0xd8 [ath11k]
>    ath11k_mac_op_bss_info_changed+0xe8/0xf60 [ath11k]
>    drv_link_info_changed+0x118/0x160 [mac80211]
>    ieee80211_link_info_change_notify+0xe0/0x100 [mac80211]
>    ieee80211_change_bss+0x1c8/0x250 [mac80211]
>    nl80211_set_bss+0x1a0/0x330 [cfg80211]
> 
> Initialise it where its credit-flow sibling ab->wmi_ab.tx_credits_wq is
> already initialised, in ath11k_core_alloc(), which runs once per device.
> The array is fixed size, so all of it can be set up before any pdev is
> attached, and nothing on the recovery path touches the head again.
> 
> Reproduced on a Xiaomi AX3600 (IPQ8074 hw2.0) with a userspace loop
> pushing beacon updates while the firmware is asserted through the debugfs
> simulate_fw_crash 'assert' trigger, on a stock ath11k with no out-of-tree
> modules loaded: one warning per recovery, on all eleven recoveries
> observed across two builds, and none at all over six recoveries with this
> applied.
> 
> Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.12-01460-QCAHKSWPL_SILICONZ-1
> 
> Fixes: f951380a6022 ("ath11k: Disabling credit flow for WMI path")
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Julius Bairaktaris <julius@bairaktaris.de>

Reviewed-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com>