[PATCH v2] staging: r8188eu: Provide a TODO file for this driver

[PATCH v2] staging: r8188eu: Provide a TODO file for this driver

[Fabio M. De Francesco]

Provide a TODO file that lists the tasks that should be carried out in
order to move this driver off drivers/staging.

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---

v1->v2: According to reviews by Fabio Aiuto <fabioaiuto83@gmail.com> and Greg K-H
	<gregkh@linuxfoundation.org>, remove "[] is currently in development...",
	indent and properly wrap the lines, remove the unnecessary last paragraph.

Thanks to Phillip Potter <phil@philpotter.co.uk> for for providing the first draft.

 drivers/staging/r8188eu/TODO | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 drivers/staging/r8188eu/TODO

diff --git a/drivers/staging/r8188eu/TODO b/drivers/staging/r8188eu/TODO
new file mode 100644
index 000000000000..d2f21b35fbcb
--- /dev/null
+++ b/drivers/staging/r8188eu/TODO
@@ -0,0 +1,12 @@
+To-do list:
+
+* Correct the coding style according to Linux guidelines; please read the document
+  at https://www.kernel.org/doc/html/latest/process/coding-style.html.
+* Remove unnecessary debugging/printing macros; for those that are still needed
+  use the proper kernel API (pr_debug(), dev_dbg(), netdev_dbg()).
+* Remove dead code such as unusued functions, variables, fields, etc..
+* Use in-kernel API and remove unnecessary wrappers where possible.
+* Remove the HAL layer and migrate its functionality into the relevant parts of
+  the driver.
+* Switch to use LIB80211.
+* Switch to use MAC80211.
-- 
2.32.0

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

[Dan Carpenter]

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
drivers/staging/r8188eu/core/rtw_ap.c:1361 update_beacon() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_ap.c:1725 ap_free_sta() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_pwrctrl.c:79 ips_leave() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_pwrctrl.c:81 ips_leave() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_mlme_ext.c:6764 receive_disconnect() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_mlme_ext.c:7083 report_del_sta_event() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_mlme_ext.c:8133 set_tx_beacon_cmd() warn: sleeping in atomic context
drivers/staging/r8188eu/os_dep/mlme_linux.c:117 rtw_report_sec_ie() warn: sleeping in atomic context

There are a few in rtl8723bs as well since the code came from the same
place.

drivers/staging/rtl8723bs/core/rtw_ap.c:1601 update_beacon() warn: sleeping in atomic context
drivers/staging/rtl8723bs/core/rtw_ap.c:1919 ap_free_sta() warn: sleeping in atomic context
drivers/staging/rtl8723bs/core/rtw_mlme_ext.c:4270 receive_disconnect() warn: sleeping in atomic context
drivers/staging/rtl8723bs/hal/hal_intf.c:100 rtw_hal_init() warn: sleeping in atomic context

regards,
dan carpenter

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

[Fabio M. De Francesco]

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
> drivers/staging/r8188eu/core/rtw_ap.c:1361 update_beacon() warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_ap.c:1725 ap_free_sta() warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_pwrctrl.c:79 ips_leave() warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_pwrctrl.c:81 ips_leave() warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_mlme_ext.c:6764 receive_disconnect() warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_mlme_ext.c:7083 report_del_sta_event() warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_mlme_ext.c:8133 set_tx_beacon_cmd() warn: sleeping in atomic context
> drivers/staging/r8188eu/os_dep/mlme_linux.c:117 rtw_report_sec_ie() warn: sleeping in atomic context
> 
> There are a few in rtl8723bs as well since the code came from the same
> place.
> 
> drivers/staging/rtl8723bs/core/rtw_ap.c:1601 update_beacon() warn: sleeping in atomic context
> drivers/staging/rtl8723bs/core/rtw_ap.c:1919 ap_free_sta() warn: sleeping in atomic context
> drivers/staging/rtl8723bs/core/rtw_mlme_ext.c:4270 receive_disconnect() warn: sleeping in atomic context
> drivers/staging/rtl8723bs/hal/hal_intf.c:100 rtw_hal_init() warn: sleeping in atomic context
> 
> regards,
> dan carpenter

Thanks for your suggestion, I'll add this too to next version.

However I prefer to wait until tomorrow because it is probable that someone else 
have think of more tasks to add to the list.

Regards,

Fabio

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

[Fabio M. De Francesco]

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
> drivers/staging/r8188eu/core/rtw_ap.c:1361 update_beacon() warn: sleeping 
in atomic context
> drivers/staging/r8188eu/core/rtw_ap.c:1725 ap_free_sta() warn: sleeping in 
atomic context
> drivers/staging/r8188eu/core/rtw_pwrctrl.c:79 ips_leave() warn: sleeping in 
atomic context
> drivers/staging/r8188eu/core/rtw_pwrctrl.c:81 ips_leave() warn: sleeping in 
atomic context
> drivers/staging/r8188eu/core/rtw_mlme_ext.c:6764 receive_disconnect() warn: 
sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_mlme_ext.c:7083 report_del_sta_event() 
warn: sleeping in atomic context
> drivers/staging/r8188eu/core/rtw_mlme_ext.c:8133 set_tx_beacon_cmd() warn: 
sleeping in atomic context
> drivers/staging/r8188eu/os_dep/mlme_linux.c:117 rtw_report_sec_ie() warn: 
sleeping in atomic context
> 
> There are a few in rtl8723bs as well since the code came from the same
> place.
> 
> drivers/staging/rtl8723bs/core/rtw_ap.c:1601 update_beacon() warn: sleeping 
in atomic context
> drivers/staging/rtl8723bs/core/rtw_ap.c:1919 ap_free_sta() warn: sleeping 
in atomic context
> drivers/staging/rtl8723bs/core/rtw_mlme_ext.c:4270 receive_disconnect() 
warn: sleeping in atomic context
> drivers/staging/rtl8723bs/hal/hal_intf.c:100 rtw_hal_init() warn: sleeping 
in atomic context
> 
> regards,
> dan carpenter
> 
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? 

Thank you in advance,

Fabio

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

[Fabio M. De Francesco]

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
> 
> 
> 
> 

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

[Dan Carpenter]

On Sun, Oct 10, 2021 at 11:21:49AM +0200, Fabio M. De Francesco wrote:
> 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.

These are a new Smatch warning.

https://lkml.org/lkml/2021/9/1/950

You would need to rebuild the Smatch database probably around five times
to see the warnings.  It takes a long time to build...  It's probably
not that hard to figure out just from looking at the code without the
generating the warning.

So spin locks can't sleep.  Mutexes can.  There are read/write locks,
built on both mutexes and spin locks.  Rcu_read/write cannot sleep.

regards,
dan carpenter

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

[Dan Carpenter]

Here it the `smdb.py preempt <func>` output for all the r8188eu warnings.
Unfiltered and unchecked.

regards,
dan carpenter

======

drivers/staging/r8188eu/core/rtw_ap.c:1080 ap_free_sta() warn: sleeping in atomic context

OnDeAuth() <- disables preempt
OnDisassoc() <- disables preempt
expire_timeout_chk() <- disables preempt
rtw_wx_set_wap() <- disables preempt
rtw_wx_set_essid() <- disables preempt
-> rtw_set_802_11_infrastructure_mode() <- disables preempt
   -> stop_ap_mode()
      -> rtw_sta_flush() <- disables preempt
rtw_del_sta() <- disables preempt
cfg80211_rtw_del_station() <- disables preempt
ap_control_kickall() <- disables preempt
         -> ap_free_sta()

======

drivers/staging/r8188eu/core/rtw_pwrctrl.c:76 ips_leave() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_pwrctrl.c:78 ips_leave() warn: sleeping in atomic context

rtw_set_802_11_disassociate() <- disables preempt
-> _rtw_pwr_wakeup()
   -> LeaveAllPowerSaveMode()
_rtw_pwr_wakeup() <duplicate>
      -> ips_leave()

======

drivers/staging/r8188eu/core/rtw_mlme.c:1602 rtw_set_key() warn: sleeping in atomic context

rtw_set_802_11_disassociate() <- disables preempt
-> _rtw_pwr_wakeup()
   -> LeaveAllPowerSaveMode()
_rtw_pwr_wakeup() <duplicate>
      -> ips_leave()
         -> _ips_leave()
ips_leave() <duplicate>
            -> rtw_ips_pwr_up()
               -> ips_netdrv_open()
                  -> rtw_hal_init()
                     -> rtw_sec_restore_wep_key()
ips_leave() <duplicate>
                        -> rtw_set_key()

======

drivers/staging/r8188eu/core/rtw_mlme_ext.c:6540 receive_disconnect() warn: sleeping in atomic context

rtw_surveydone_event_callback() <- disables preempt
-> receive_disconnect()

======

drivers/staging/r8188eu/core/rtw_mlme_ext.c:6859 report_del_sta_event() warn: sleeping in atomic context

rtw_surveydone_event_callback() <- disables preempt
-> receive_disconnect()
OnDeAuth() <- disables preempt
OnDisassoc() <- disables preempt
expire_timeout_chk() <- disables preempt
rtw_wx_set_wap() <- disables preempt
rtw_wx_set_essid() <- disables preempt
-> rtw_set_802_11_infrastructure_mode() <- disables preempt
   -> stop_ap_mode()
      -> rtw_sta_flush() <- disables preempt
rtw_del_sta() <- disables preempt
cfg80211_rtw_del_station() <- disables preempt
ap_control_kickall() <- disables preempt
         -> ap_free_sta()
            -> report_del_sta_event()

======

drivers/staging/r8188eu/os_dep/mlme_linux.c:115 rtw_report_sec_ie() warn: sleeping in atomic context

rtw_set_802_11_ssid() <- disables preempt
rtw_set_802_11_connect() <- disables preempt
_rtw_join_timeout_handler() <- disables preempt
rtw_stadel_event_callback() <- disables preempt
rtw_roaming() <- disables preempt
-> _rtw_roaming()
rtw_set_802_11_bssid() <- disables preempt
   -> rtw_do_join()
rtw_surveydone_event_callback() <- disables preempt
      -> rtw_select_and_join_from_scanned_queue() <- disables preempt
         -> rtw_joinbss_cmd()
            -> rtw_restruct_sec_ie()
               -> rtw_report_sec_ie()

======

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

[Fabio M. De Francesco]

On Monday, October 11, 2021 10:21:34 AM CEST Dan Carpenter wrote:
> On Sun, Oct 10, 2021 at 11:21:49AM +0200, Fabio M. De Francesco wrote:
> > 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.
> 
> These are a new Smatch warning.
> 
> https://lkml.org/lkml/2021/9/1/950
> 
> You would need to rebuild the Smatch database probably around five times
> to see the warnings.  It takes a long time to build...  It's probably
> not that hard to figure out just from looking at the code without the
> generating the warning.

I must confess that, since I started to submit patches to the Kernel this 
year in April and until now, I have not ever used Smatch. I thought that 
building with GCC and setting C=2 and W=1 were enough. Sometimes I've 
also used Coccinelle. That's all.

Now I admit that I was plainly wrong. My _big_ fault, sorry :(

This morning I have taken a quick look at your code at https://github.com/
error27/smatch. Obviously, what I could see is only the overall design and it 
looks quite impressive. I'll start using Smatch soon.

> So spin locks can't sleep.  Mutexes can.  There are read/write locks,
> built on both mutexes and spin locks.  Rcu_read/write cannot sleep.

Oh, right. RCU were missing from my lists.

Thanks very much for Smatch and for your kind replies.

Regards,

Fabio M. De Francesco

P.S.: Yesterday I read the first one third of a paper co-authored by Julia 
Lawall (Effective Detection of Sleep-in-atomic-context Bugs
in the Linux Kernel - https://doi.org/10.1145/3381990). 

It talks about a practical static approach named DSAC. It looks really 
interesting, but it seems that their tool is not yet available to the public. 

Do you know something about it? I've found an old message by Greg K-H that 
asked for where to find that tool but, as far as I know, he have not yet had 
that information. With this message I've Cc'd Julia in case she has time to 
reply.

> regards,
> dan carpenter
> 
>