Ping-Ke Shih <pkshih@xxxxxxxxxxx> wrote:
> The ieee80211_ops::sta_rc_update must be atomic, because
> ieee80211_chan_bw_change() holds rcu_read lock while calling
> drv_sta_rc_update(), so create a work to do original things.
>
> Voluntary context switch within RCU read-side critical section!
> WARNING: CPU: 0 PID: 4621 at kernel/rcu/tree_plugin.h:318
> rcu_note_context_switch+0x571/0x5d0
> CPU: 0 PID: 4621 Comm: kworker/u16:2 Tainted: G W OE
> Workqueue: phy3 ieee80211_chswitch_work [mac80211]
> RIP: 0010:rcu_note_context_switch+0x571/0x5d0
> Call Trace:
> <TASK>
> __schedule+0xb0/0x1460
> ? __mod_timer+0x116/0x360
> schedule+0x5a/0xc0
> schedule_timeout+0x87/0x150
> ? trace_raw_output_tick_stop+0x60/0x60
> wait_for_completion_timeout+0x7b/0x140
> usb_start_wait_urb+0x82/0x160 [usbcore
> usb_control_msg+0xe3/0x140 [usbcore
> rtw_usb_read+0x88/0xe0 [rtw_usb
> rtw_usb_read8+0xf/0x10 [rtw_usb
> rtw_fw_send_h2c_command+0xa0/0x170 [rtw_core
> rtw_fw_send_ra_info+0xc9/0xf0 [rtw_core
> drv_sta_rc_update+0x7c/0x160 [mac80211
> ieee80211_chan_bw_change+0xfb/0x110 [mac80211
> ieee80211_change_chanctx+0x38/0x130 [mac80211
> ieee80211_vif_use_reserved_switch+0x34e/0x900 [mac80211
> ieee80211_link_use_reserved_context+0x88/0xe0 [mac80211
> ieee80211_chswitch_work+0x95/0x170 [mac80211
> process_one_work+0x201/0x410
> worker_thread+0x4a/0x3b0
> ? process_one_work+0x410/0x410
> kthread+0xe1/0x110
> ? kthread_complete_and_exit+0x20/0x20
> ret_from_fork+0x1f/0x30
> </TASK>
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: c1edc86472fc ("rtw88: add ieee80211:sta_rc_update ops")
> Reported-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
> Link: https://lore.kernel.org/linux-wireless/f1e31e8e-f84e-3791-50fb-663a83c5c6e9@xxxxxxxxxxxx/T/#t
> Signed-off-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx>
> Tested-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Patch applied to wireless.git, thanks.
bcafcb959a57 wifi: rtw88: use work to update rate to avoid RCU warning
--
https://patchwork.kernel.org/project/linux-wireless/patch/20230508085429.46653-1-pkshih@xxxxxxxxxxx/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
