linux-kernel - Re: [PATCH v2] staging: r8188eu: Provide a TODO file for this driver

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Date:   Sun, 10 Oct 2021 11:21:49 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        linux-staging@...ts.linux.dev
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: r8188eu: Provide a TODO file for this driver

On Saturday, October 9, 2021 6:31:12 PM CEST Fabio M. De Francesco wrote:
> On Thursday, August 26, 2021 3:54:13 PM CEST Dan Carpenter wrote:
> > Another thing to fix are some of the sleeping in atomic bugs.
> > 
> > drivers/staging/r8188eu/core/rtw_ap.c:139 update_BCNTIM() warn: sleeping
> > in atomic context
> > drivers/staging/r8188eu/core/rtw_ap.c:1296 update_bcn_wps_ie() warn: 
> > sleeping in atomic context
> >
> > [...]
> >
> Hello Dan,
> 
> I'd like to address these kind of bugs, but I have a couple of questions 
> about them.
> 
> 1) You've listed what looks like the output of a compiler or static
> analyzer. 
> How did you get the warnings you copy-pasted above?
> 
> 2) I know that both the execution of interrupt handlers (ISRs) as well as
> any 
> code blocks that are executed holding spinlocks are "atomic contexts". In 
> these cases, "sleeping" is not allowed (for obvious reasons). Besides the
> two 
> mentioned above, are there any further cases of "atomic contexts" in the 
> kernel?

After some research, I've found that Softirqs and Tasklets are also executed 
in "atomic context", as hardware interrupt service routines are.

Furthermore, I've also found a .config option named DEBUG_ATOMIC_SLEEP
that should warn if some code is sleeping in "atomic context". However, the 
documentation of that option does not explain where the output of these 
checks can be read.

I would appreciate any help on this matter.

Thanks,

Fabio
 
> 
> Thank you in advance,
> 
> Fabio
> 
> 
> 
>