Messages in this thread | | | Date | Fri, 21 Oct 2022 14:32:12 +0800 (GMT+08:00) | From | duoming@zju ... | Subject | Re: [PATCH] drivers: staging: r8188eu: Fix sleep-in-atomic-context bug in rtw_join_timeout_handler |
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Hello,
On Thu, 20 Oct 2022 17:46:47 +0200 Greg KH wrote:
> On Tue, Oct 18, 2022 at 04:34:24PM +0800, Duoming Zhou wrote: > > The rtw_join_timeout_handler() is a timer handler that > > runs in atomic context, but it could call msleep(). > > As a result, the sleep-in-atomic-context bug will happen. > > The process is shown below: > > > > (atomic context) > > rtw_join_timeout_handler > > Wait, how is this an atomic timeout?
Because this function is defined as a timer handler of "assoc_timer".
The following is the detail:
void rtw_init_mlme_timer(struct adapter *padapter) { struct mlme_priv *pmlmepriv = &padapter->mlmepriv;
timer_setup(&pmlmepriv->assoc_timer, rtw_join_timeout_handler, 0); ... }
https://elixir.bootlin.com/linux/latest/source/drivers/staging/r8188eu/os_dep/mlme_linux.c#L36
> When can that happen?
When the adapter trys to join and selects scanning queue successfully, the assoc_timer will be actived. If this process is timeout, the callback function rtw_join_timeout_handler will run.
> > _rtw_join_timeout_handler > > rtw_do_join > > rtw_select_and_join_from_scanned_queue > > rtw_indicate_disconnect > > rtw_lps_ctrl_wk_cmd > > lps_ctrl_wk_hdl > > LPS_Leave > > LPS_RF_ON_check > > msleep //sleep in atomic context > > How was this found? > > > Fix by removing msleep() and replacing with mdelay(). > > Wouldn't people have seen an error already if msleep() was really called > in atomic context?
I am sorry, This is the false alarm.
rtw_indicate_disconnect() -->rtw_lps_ctrl_wk_cmd(padapter, LPS_CTRL_DISCONNECT, 1);
u8 rtw_lps_ctrl_wk_cmd(struct adapter *padapter, u8 lps_ctrl_type, u8 enqueue) { ... if (enqueue) { ... }else { lps_ctrl_wk_hdl(padapter, lps_ctrl_type); }
The enqueue equals to 1 and the lps_ctrl_wk_hdl() will not execute.
I will check carefully and avoid false alarm next time. Thank you for your reply.
Best regards, Duoming Zhou | |