On 11/13/2024 7:12 PM, Kalle Valo wrote:
> Baochen Qiang <quic_bqiang@xxxxxxxxxxx> writes:
>
>> We get report [1] that CPU is running a hot loop in
>> ath11k_debugfs_fw_stats_request():
>>
>> 94.60% 0.00% i3status [kernel.kallsyms] [k] do_syscall_64
>> |
>> --94.60%--do_syscall_64
>> |
>> --94.55%--__sys_sendmsg
>> ___sys_sendmsg
>> ____sys_sendmsg
>> netlink_sendmsg
>> netlink_unicast
>> genl_rcv
>> netlink_rcv_skb
>> genl_rcv_msg
>> |
>> --94.55%--genl_family_rcv_msg_dumpit
>> __netlink_dump_start
>> netlink_dump
>> genl_dumpit
>> nl80211_dump_station
>> |
>> --94.55%--ieee80211_dump_station
>> sta_set_sinfo
>> |
>> --94.55%--ath11k_mac_op_sta_statistics
>> ath11k_debugfs_get_fw_stats
>> |
>> --94.55%--ath11k_debugfs_fw_stats_request
>> |
>> |--41.73%--_raw_spin_lock_bh
>> |
>> |--22.74%--__local_bh_enable_ip
>> |
>> |--9.22%--_raw_spin_unlock_bh
>> |
>> --6.66%--srso_alias_safe_ret
>>
>> This is because, if for whatever reason ar->fw_stats_done is not set by
>> ath11k_update_stats_event(), ath11k_debugfs_fw_stats_request() won't yield
>> CPU before an up to 3s timeout.
>>
>> Add 100ms sleep to avoid CPU burning.
>>
>> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.37
>>
>> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
>> Reported-by: Yury Vostrikov <mon@xxxxxxxxxxx>
>> Closes: https://lore.kernel.org/all/7324ac7a-8b7a-42a5-aa19-de52138ff638@xxxxxxxxxxxxxxxx/ # [1]
>> Signed-off-by: Baochen Qiang <quic_bqiang@xxxxxxxxxxx>
>> ---
>> drivers/net/wireless/ath/ath11k/debugfs.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/wireless/ath/ath11k/debugfs.c b/drivers/net/wireless/ath/ath11k/debugfs.c
>> index 57281a135dd7..a5e0f2092da5 100644
>> --- a/drivers/net/wireless/ath/ath11k/debugfs.c
>> +++ b/drivers/net/wireless/ath/ath11k/debugfs.c
>> @@ -207,6 +207,9 @@ static int ath11k_debugfs_fw_stats_request(struct ath11k *ar,
>> break;
>> }
>> spin_unlock_bh(&ar->data_lock);
>> +
>> + /* 100ms is empirical, change if required */
>> + msleep(100);
>> }
>> return 0;
>> }
>
> Please don't reinvent the wheel. Why not just use completion instead of
> this ugly spinning hack?
previously I was thinking that a wait_for_completion() is not allowed since we are in atomic context due to spin_lock. But thinking it more I find that after changing to use completion, the spin_lock is not necessary. so thanks, will do in next version.
>
