Messages in this thread | | | Date | Sat, 2 Apr 2022 16:32:50 -0500 | Subject | Re: staging: r8188eu: how to handle nested mutex under spinlock | From | Larry Finger <> |
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On 4/2/22 15:47, Michael Straube wrote: > Hi all, > > smatch reported a sleeping in atomic context. > > rtw_set_802_11_disassociate() <- disables preempt > -> _rtw_pwr_wakeup() > -> ips_leave() > > rtw_set_802_11_disassociate() takes a spinlock and ips_leave() uses a > mutex. > > I'm fairly new to the locking stuff, but as far as I know this is not a > false positive since mutex can sleep, but that's not allowed under a > spinlock. > > What is the best way to handle this? > I'm not sure if converting the mutex to a spinlock (including all the > other places where the mutex is used) is the right thing to do?
In drivers/net/wireless/realtek/rtlwifi, we had a similar problem. There it was handled by putting the lps_enter() and lps_leave() operations in a separate workqueue. In this case, the routines were rtl_lps_enter() and rtl_lps_leave(). Each of them sets a variable to indicate whether enter_ps is true or false, and schedules the workqueue. In the workqueue's callback routine, the routines to start/stop ps mode are called. The code is in drivers/net/wireless/realtek/rtlwifi/ps.c.
This solution is only one of many, and there may be a better one.
Larry
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