Re: [PATCH v2 2/2] wifi: ath12k: Fix firmware stats leak when pdev list is empty

Baochen Qiang
2026-01-30T07:51:00Z

On 1/30/2026 3:32 PM, Saikiran B wrote:
> On Fri, Jan 30, 2026 at 7:39 AM Baochen Qiang
> <baochen.qiang@oss.qualcomm.com> wrote:
>>
>>
>>
>> On 1/29/2026 10:06 PM, Saikiran B wrote:
>>> On Thu, Jan 29, 2026 at 7:57 AM Baochen Qiang
>>> <baochen.qiang@oss.qualcomm.com> wrote:
>>>>
>>>>
>>>>
>>>> On 1/27/2026 12:40 PM, Saikiran B wrote:
>>>>> I have analyzed the logs and code flow in depth to provide more
>>>>> definitive answers for your questions.
>>>>>
>>>>> The log entries showing the failure are:
>>>>> [ 563.574076] ath12k_pci 0004:01:00.0: failed to pull fw stats: -71
>>>>> [ 564.575896] ath12k_pci 0004:01:00.0: time out while waiting for get fw stats
>>>>>
>>>>> 1. Why are other stats populated?
>>>>> The "failed to pull fw stats: -71" error is not the initial failure
>>>>> but a symptom that appears after repeated operations. The leak happens
>>>>> during *successful* calls prior to this error.
>>>>>
>>>>> Code flow proving the leak:
>>>>> - ath12k_mac_get_fw_stats() sends WMI_REQUEST_PDEV_STAT.
>>>>> - Firmware responds. ath12k_update_stats_event() parses the response.
>>>>> - ath12k_wmi_fw_stats_process() is called, which splices 'vdevs' and
>>>>> 'beacon' stats into ar->fw_stats.vdevs/bcn.
>>>>> - ath12k_mac_get_fw_stats() returns 0 (Success).
>>>>> - In ath12k_mac_op_get_txpower(), the check `if (!pdev)` fails if the
>>>>> pdev-specific list is empty (but vdev list is NOT empty).
>>>>> - The function exits via `err_fallback` WITHOUT calling ath12k_fw_stats_reset().
>>>>> - Result: The 'vdev' and 'beacon' stats that were spliced into
>>>>> ar->fw_stats remain there, leaking memory and accumulating with every
>>>>> call.
>>>>>
>>>>> 2. Exact place where -71 is printed:
>>>>> The error "failed to pull fw stats: -71" is printed in
>>>>> [ath12k_update_stats_event()](drivers/net/wireless/ath/ath12k/wmi.c).
>>>>> It corresponds to "ret = ath12k_wmi_pull_fw_stats()" returning -EPROTO.
>>>>> This propagates from
>>>>> [ath12k_wmi_tlv_fw_stats_data_parse()](drivers/net/wireless/ath/ath12k/wmi.c),
>>>>> when buffer validation checks (like `len < sizeof(*src)`) fail.
>>>>>
>>>>> Conclusion:
>>>>> The fix in my patch (resetting stats when `!pdev`) is critical because
>>>>> it ensures that the accumulated 'vdev' and 'beacon' stats are freed
>>>>> even when the 'pdev' list ends up empty.
>>>>>
>>>>> Let me know if you need anything else.
>>>>
>>>> can you please try below to see if it can fix your issue?
>>>>
>>>> https://lore.kernel.org/r/20260129-ath12k-fw-stats-fixes-v1-0-55d66064f4d5@oss.qualcomm.com
>>>>
>>>>>
>>>>> Thanks & Regards,
>>>>> Saikiran
>>>>>
>>>>> On Tue, Jan 27, 2026 at 9:47 AM Saikiran B <bjsaikiran@gmail.com> wrote:
>>>>>>
>>>>>> Hi Baochen,
>>>>>>
>>>>>> Regarding your questions:
>>>>>>
>>>>>> "Are other stats populated?"
>>>>>>
>>>>>> Yes. When ath12k_mac_get_fw_stats() returns success (0), it means the
>>>>>> firmware response was received and valid WMI events were processed.
>>>>>> The firmware response to WMI_REQUEST_PDEV_STAT typically includes
>>>>>> multiple stats TLVs (vdev stats, beacon stats, etc.). Even if the
>>>>>> "pdev stats" list ends up empty (e.g., due to specific filtering or
>>>>>> availability), the firmware should have populated other lists (like
>>>>>> vdevs or beacons) in the ar->fw_stats structure. If we don't reset,
>>>>>> these valid entries leak and accumulate.
>>>>>>
>>>>>> "Where exactly is -71 (EPROTO) printed?"
>>>>>>
>>>>>> The log "failed to pull fw stats: -71" is printed in
>>>>>> ath12k_update_stats_event() (wmi.c line 8500 in my tree). This error
>>>>>> code (-EPROTO) propagates from ath12k_wmi_tlv_fw_stats_data_parse(),
>>>>>> where it is returned when buffer validation checks fail (e.g., if (len
>>>>>> < sizeof(*src))). This failure suggests that the accumulated state or
>>>>>> memory corruption from the leak eventually causes the parser to fail
>>>>>> on subsequent events.
>>>>>>
>>>>>> So, fixing the leak is necessary for correctness regardless of the
>>>>>> specific side-effect error code.
>>>>>>
>>>>>> Thanks & Regards,
>>>>>> Saikiran
>>>>>>
>>>>>> On Tue, Jan 27, 2026 at 8:57 AM Baochen Qiang
>>>>>> <baochen.qiang@oss.qualcomm.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 1/26/2026 5:52 PM, Saikiran wrote:
>>>>>>>> The commits bd6ec8111e65 and 2977567b244f changed firmware stats handling
>>>>>>>> to be caller-driven, requiring explicit ath12k_fw_stats_reset() calls
>>>>>>>> after using ath12k_mac_get_fw_stats().
>>>>>>>>
>>>>>>>> In ath12k_mac_op_get_txpower(), when ath12k_mac_get_fw_stats() succeeds
>>>>>>>> but the pdev stats list is empty, the function exits without calling
>>>>>>>> ath12k_fw_stats_reset(). Even though the pdev list is empty, the firmware
>>>>>>>> may have populated other stats lists (vdevs, beacons, etc.) in the
>>>>>>>
>>>>>>> 'may' is not enough, we need to be 100% sure whether other stats are populated. This is
>>>>>>> critical for us to find the root cause.
>>>>>>>
>>>>>>>> ar->fw_stats structure.
>>>>>>>>
>>>>>>>> Without resetting the stats buffer, this data accumulates across multiple
>>>>>>>> calls, eventually causing the stats buffer to overflow and leading to
>>>>>>>> firmware communication failures (error -71/EPROTO) during subsequent
>>>>>>>> operations.
>>>>>>>>
>>>>>>>> The issue manifests during 5GHz scanning which triggers multiple TX power
>>>>>>>> queries. Symptoms include:
>>>>>>>> - "failed to pull fw stats: -71" errors in dmesg
>>>>>>>
>>>>>>> still, can you please check the logs to see at which exact place is this printed?
>>>>>>>
>>>>>>>> - 5GHz networks not detected despite hardware support
>>>>>>>> - 2.4GHz networks work normally
>>>>>>>>
>>>>>>>> Fix by calling ath12k_fw_stats_reset() when the pdev list is empty,
>>>>>>>> ensuring the stats buffer is properly cleaned up even when only partial
>>>>>>>> stats data is received from firmware.
>>>>>>>>
>>>>>>>> Fixes: bd6ec8111e65 ("wifi: ath12k: Make firmware stats reset caller-driven")
>>>>>>>> Link: https://bugs.launchpad.net/ubuntu-concept/+bug/2138308
>>>>>>>> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302 (Lenovo Yoga Slim 7x)
>>>>>>>> Signed-off-by: Saikiran <bjsaikiran@gmail.com>
>>>>>>>> ---
>>>>>>>> drivers/net/wireless/ath/ath12k/mac.c | 1 +
>>>>>>>> 1 file changed, 1 insertion(+)
>>>>>>>>
>>>>>>>> diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
>>>>>>>> index e0e49f782bf8..6e35c3ee9864 100644
>>>>>>>> --- a/drivers/net/wireless/ath/ath12k/mac.c
>>>>>>>> +++ b/drivers/net/wireless/ath/ath12k/mac.c
>>>>>>>> @@ -5169,6 +5169,7 @@ static int ath12k_mac_op_get_txpower(struct ieee80211_hw *hw,
>>>>>>>> struct ath12k_fw_stats_pdev, list);
>>>>>>>> if (!pdev) {
>>>>>>>> spin_unlock_bh(&ar->data_lock);
>>>>>>>> + ath12k_fw_stats_reset(ar);
>>>>>>>> goto err_fallback;
>>>>>>>> }
>>>>>>>>
>>>>>>>
>>>>
>>>
>>> Hi Baochen,
>>>
>>> I tried applying your patches on top of v6.19-rc7 (which is the latest
>>> mainline release candidate I'm testing on), but I ran into build
>>> issues because some of the dependencies seem missing.
>>>
>>> Specifically:
>>> Patch 2 ("wifi: ath12k: fix station lookup failure when disconnecting
>>> from AP") uses `ath12k_link_sta_find_by_addr()`, which does not exist
>>> in my tree. It seems your patches are based on a different tree
>>> (ath-next?) that has newer changes not yet in the mainline.
>>>
>>> Could you please point me to the specific git repo/branch you are
>>> using? I can try to build and test on that baseline to be sure.
>>
>> My bad. Please try the latest ath tree:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/ath/ath.git/
>>
>> the base commit is ath-202601271544 tag.
>>
>>>
>>> Regarding the firmware stats issue:
>>> I verified the firmware files match the latest available (MD5 sums
>>> matched), yet the "-71" errors and memory leak persist on my device
>>> without fixes.
>>>
>>> I successfully applied the logic from your Patch 1 manually (since
>>> [ath12k_mac_get_target_pdev_id](cci:1://file:///home/saikiran/linux/kernel/x1e/x1e/drivers/net/wireless/ath/ath12k/mac.c:989:0-1008:1)
>>> exists), but I haven't fully validated if it alone resolves the leak
>>> in all scenarios.
>>>
>>> However, the fix I proposed in my v2 patch (resetting stats when pdev
>>> list is empty) definitely stops the leak mechanism by ensuring cleanup
>>> happens even when the firmware returns partial stats (which seems to
>>> be the trigger condition).
>>>
>>> I'll wait for your pointer to the base tree to do a proper test of your series.
>>>
>>> Thanks & Regards,
>>> Saikiran
>>
>
> Hi,
>
> I have merged the tag, applied your patches and I can confirm that the
> leak has been fixed.

Thank you Saikiran for the test!

>
> Thanks & Regards,
> Saikiran