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?
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