linux-kernel - Re: [PATCH 2/5] ath10k: fix WARNING: suspicious RCU usage

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Message-ID: <7230c9e5-2632-b77e-c4f9-10eca557a5bb@linuxfoundation.org>
Date:   Wed, 10 Feb 2021 09:22:42 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     davem@...emloft.net, kuba@...nel.org, ath10k@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 2/5] ath10k: fix WARNING: suspicious RCU usage

On 2/10/21 1:13 AM, Kalle Valo wrote:
> Shuah Khan <skhan@...uxfoundation.org> wrote:
> 
>> ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
>> the resulting pointer is only valid under RCU lock as well.
>>
>> Fix ath10k_wmi_tlv_parse_peer_stats_info() to hold RCU lock before it
>> calls ieee80211_find_sta_by_ifaddr() and release it when the resulting
>> pointer is no longer needed. The log below shows the problem.
>>
>> While at it, fix ath10k_wmi_tlv_op_pull_peer_stats_info() to do the same.
>>
>> =============================
>> WARNING: suspicious RCU usage
>> 5.11.0-rc7+ #20 Tainted: G        W
>> -----------------------------
>> include/linux/rhashtable.h:594 suspicious rcu_dereference_check() usage!
>> other info that might help us debug this:
>>                 rcu_scheduler_active = 2, debug_locks = 1
>> no locks held by ksoftirqd/5/44.
>>
>> stack backtrace:
>> CPU: 5 PID: 44 Comm: ksoftirqd/5 Tainted: G        W         5.11.0-rc7+ #20
>> Hardware name: LENOVO 10VGCTO1WW/3130, BIOS M1XKT45A 08/21/2019
>> Call Trace:
>>   dump_stack+0x7d/0x9f
>>   lockdep_rcu_suspicious+0xdb/0xe5
>>   __rhashtable_lookup+0x1eb/0x260 [mac80211]
>>   ieee80211_find_sta_by_ifaddr+0x5b/0xc0 [mac80211]
>>   ath10k_wmi_tlv_parse_peer_stats_info+0x3e/0x90 [ath10k_core]
>>   ath10k_wmi_tlv_iter+0x6a/0xc0 [ath10k_core]
>>   ? ath10k_wmi_tlv_op_pull_mgmt_tx_bundle_compl_ev+0xe0/0xe0 [ath10k_core]
>>   ath10k_wmi_tlv_op_rx+0x5da/0xda0 [ath10k_core]
>>   ? trace_hardirqs_on+0x54/0xf0
>>   ? ath10k_ce_completed_recv_next+0x4e/0x60 [ath10k_core]
>>   ath10k_wmi_process_rx+0x1d/0x40 [ath10k_core]
>>   ath10k_htc_rx_completion_handler+0x115/0x180 [ath10k_core]
>>   ath10k_pci_process_rx_cb+0x149/0x1b0 [ath10k_pci]
>>   ? ath10k_htc_process_trailer+0x2d0/0x2d0 [ath10k_core]
>>   ? ath10k_pci_sleep.part.0+0x6a/0x80 [ath10k_pci]
>>   ath10k_pci_htc_rx_cb+0x15/0x20 [ath10k_pci]
>>   ath10k_ce_per_engine_service+0x61/0x80 [ath10k_core]
>>   ath10k_ce_per_engine_service_any+0x7d/0xa0 [ath10k_core]
>>   ath10k_pci_napi_poll+0x48/0x120 [ath10k_pci]
>>   net_rx_action+0x136/0x500
>>   __do_softirq+0xc6/0x459
>>   ? smpboot_thread_fn+0x2b/0x1f0
>>   run_ksoftirqd+0x2b/0x60
>>   smpboot_thread_fn+0x116/0x1f0
>>   kthread+0x14b/0x170
>>   ? smpboot_register_percpu_thread+0xe0/0xe0
>>   ? __kthread_bind_mask+0x70/0x70
>>   ret_from_fork+0x22/0x30
>>
>> Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
> 
> Unlucky timing also on this one, it conflicts with a patch I applied yesterday:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=ath-next&id=2615e3cdbd9c0e864f5906279c952a309871d225
> 
> Can you redo the patch to only change ath10k_wmi_event_tdls_peer()?
> 

Yes. I will send the patch just for ath10k_wmi_event_tdls_peer()
on top of your patch.

> error: patch failed: drivers/net/wireless/ath/ath10k/wmi-tlv.c:240
> error: drivers/net/wireless/ath/ath10k/wmi-tlv.c: patch does not apply
> stg import: Diff does not apply cleanly
> 
> Patch set to Changes Requested.
> 

thanks,
-- Shuah