[PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[Fabio Aiuto]

protect sleepq_len access by sleep_q.lock and move
pxmitpriv->lock after sleep_q.lock release.

This fixes and completes a lockdep warning silencing
done in a prevoius commit where accesses to sleep_q
related fields were protected by sleep_q.lock instead
of pxmitpriv->lock.

Note that sleep_q.lock is already taken inside
rtw_free_xmitframe_queue so we just wrap sleepq_len
access.

Moved pxmitpriv->lock after sleep_q.lock release to
avoid locks nesting.

Fixes: 78a1614a81f0 ("staging: rtl8723bs: remove possible deadlock when disconnect")
Reported-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
---
 drivers/staging/rtl8723bs/core/rtw_sta_mgt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c b/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
index bf090f3b1db6..c98918e02afe 100644
--- a/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
+++ b/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
@@ -294,10 +294,12 @@ u32 rtw_free_stainfo(struct adapter *padapter, struct sta_info *psta)
 
 	/* list_del_init(&psta->wakeup_list); */
 
-	spin_lock_bh(&pxmitpriv->lock);
-
 	rtw_free_xmitframe_queue(pxmitpriv, &psta->sleep_q);
+	spin_lock_bh(&psta->sleep_q.lock);
 	psta->sleepq_len = 0;
+	spin_unlock_bh(&psta->sleep_q.lock);
+
+	spin_lock_bh(&pxmitpriv->lock);
 
 	/* vo */
 	/* spin_lock_bh(&(pxmitpriv->vo_pending.lock)); */
-- 
2.20.1

Re: [PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[Hans de Goede]

Hi Fabio,

On 9/13/21 3:03 PM, Fabio Aiuto wrote:
> protect sleepq_len access by sleep_q.lock and move
> pxmitpriv->lock after sleep_q.lock release.
> 
> This fixes and completes a lockdep warning silencing
> done in a prevoius commit where accesses to sleep_q
> related fields were protected by sleep_q.lock instead
> of pxmitpriv->lock.
> 
> Note that sleep_q.lock is already taken inside
> rtw_free_xmitframe_queue so we just wrap sleepq_len
> access.
> 
> Moved pxmitpriv->lock after sleep_q.lock release to
> avoid locks nesting.
> 
> Fixes: 78a1614a81f0 ("staging: rtl8723bs: remove possible deadlock when disconnect")
> Reported-by: Hans de Goede <hdegoede@redhat.com>
> Tested-by: Fabio Aiuto <fabioaiuto83@gmail.com>
> Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
> ---
>  drivers/staging/rtl8723bs/core/rtw_sta_mgt.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c b/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
> index bf090f3b1db6..c98918e02afe 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
> @@ -294,10 +294,12 @@ u32 rtw_free_stainfo(struct adapter *padapter, struct sta_info *psta)
>  
>  	/* list_del_init(&psta->wakeup_list); */
>  
> -	spin_lock_bh(&pxmitpriv->lock);
> -
>  	rtw_free_xmitframe_queue(pxmitpriv, &psta->sleep_q);
> +	spin_lock_bh(&psta->sleep_q.lock);

AFAICT this needs to be above the rtw_free_xmitframe_queue() ?

Regards,

Hans


>  	psta->sleepq_len = 0;
> +	spin_unlock_bh(&psta->sleep_q.lock);
> +
> +	spin_lock_bh(&pxmitpriv->lock);
>  
>  	/* vo */
>  	/* spin_lock_bh(&(pxmitpriv->vo_pending.lock)); */
> 

Re: [PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[Fabio Aiuto]

Hello Hans,

On Mon, Sep 13, 2021 at 03:24:44PM +0200, Hans de Goede wrote:
> Hi Fabio,
> 
 
> > Note that sleep_q.lock is already taken inside
> > rtw_free_xmitframe_queue so we just wrap sleepq_len
> > access.
> > 
> > Moved pxmitpriv->lock after sleep_q.lock release to
> > avoid locks nesting.

> >  	rtw_free_xmitframe_queue(pxmitpriv, &psta->sleep_q);
> > +	spin_lock_bh(&psta->sleep_q.lock);
> 
> AFAICT this needs to be above the rtw_free_xmitframe_queue() ?

as I wrote on the changelog, the sleep_q.lock is already
taken inside rtw_free_xmitframe_queue. If I put the
sleep_q.lock above that function a soft lock occurs when
I disconnect.

So I put it just below rtw_free_xmitframe_queue.

Things works fine this way.

Please tell me if there's a best way to do it.

> 
> Regards,
> 
> Hans

thank you,

fabio

Re: [PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[Hans de Goede]

Hi Fabio,

On 9/13/21 3:39 PM, Fabio Aiuto wrote:
> Hello Hans,
> 
> On Mon, Sep 13, 2021 at 03:24:44PM +0200, Hans de Goede wrote:
>> Hi Fabio,
>>
>  
>>> Note that sleep_q.lock is already taken inside
>>> rtw_free_xmitframe_queue so we just wrap sleepq_len
>>> access.
>>>
>>> Moved pxmitpriv->lock after sleep_q.lock release to
>>> avoid locks nesting.
> 
>>>  	rtw_free_xmitframe_queue(pxmitpriv, &psta->sleep_q);
>>> +	spin_lock_bh(&psta->sleep_q.lock);
>>
>> AFAICT this needs to be above the rtw_free_xmitframe_queue() ?
> 
> as I wrote on the changelog, the sleep_q.lock is already
> taken inside rtw_free_xmitframe_queue. If I put the
> sleep_q.lock above that function a soft lock occurs when
> I disconnect.
> 
> So I put it just below rtw_free_xmitframe_queue.
> 
> Things works fine this way.
> 
> Please tell me if there's a best way to do it.

Hmm I see, this may work, but the sleepq_len access
really should be protected by the same lock as the freeing
of the queue is without dropping it in between.

That rtw_free_xmitframe_queue() takes the sleep_q.lock
then to me that signals that other (higher-level) functions should
not take sleep_q.lock at all, since this is then private to the
functions operating on the sleep_q.

I've an idea how we we can possibly tackle this, but I'm not sure
yet I will try to make some time to look into this tomorrow or
the day after.

Regards,

Hans

Re: [PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[Greg KH]

On Mon, Sep 13, 2021 at 05:12:19PM +0200, Hans de Goede wrote:
> Hi Fabio,
> 
> On 9/13/21 3:39 PM, Fabio Aiuto wrote:
> > Hello Hans,
> > 
> > On Mon, Sep 13, 2021 at 03:24:44PM +0200, Hans de Goede wrote:
> >> Hi Fabio,
> >>
> >  
> >>> Note that sleep_q.lock is already taken inside
> >>> rtw_free_xmitframe_queue so we just wrap sleepq_len
> >>> access.
> >>>
> >>> Moved pxmitpriv->lock after sleep_q.lock release to
> >>> avoid locks nesting.
> > 
> >>>  	rtw_free_xmitframe_queue(pxmitpriv, &psta->sleep_q);
> >>> +	spin_lock_bh(&psta->sleep_q.lock);
> >>
> >> AFAICT this needs to be above the rtw_free_xmitframe_queue() ?
> > 
> > as I wrote on the changelog, the sleep_q.lock is already
> > taken inside rtw_free_xmitframe_queue. If I put the
> > sleep_q.lock above that function a soft lock occurs when
> > I disconnect.
> > 
> > So I put it just below rtw_free_xmitframe_queue.
> > 
> > Things works fine this way.
> > 
> > Please tell me if there's a best way to do it.
> 
> Hmm I see, this may work, but the sleepq_len access
> really should be protected by the same lock as the freeing
> of the queue is without dropping it in between.
> 
> That rtw_free_xmitframe_queue() takes the sleep_q.lock
> then to me that signals that other (higher-level) functions should
> not take sleep_q.lock at all, since this is then private to the
> functions operating on the sleep_q.
> 
> I've an idea how we we can possibly tackle this, but I'm not sure
> yet I will try to make some time to look into this tomorrow or
> the day after.

I'm just going to go and revert the original change here until you all
can sort it out :)

thanks,

greg k-h

Re: [PATCH] staging: rtl8723bs: protect sleepq_len access by sleep_q.lock

[Fabio Aiuto]

Hi Greg,

On Fri, Sep 17, 2021 at 04:25:12PM +0200, Greg KH wrote:
> On Mon, Sep 13, 2021 at 05:12:19PM +0200, Hans de Goede wrote:
> > Hi Fabio,
> > 
> > On 9/13/21 3:39 PM, Fabio Aiuto wrote:
> > > Hello Hans,
> > > 
> > > On Mon, Sep 13, 2021 at 03:24:44PM +0200, Hans de Goede wrote:
> > >> Hi Fabio,
> > >>
> > >  
> > >>> Note that sleep_q.lock is already taken inside
> > >>> rtw_free_xmitframe_queue so we just wrap sleepq_len
> > >>> access.
> > >>>
> > >>> Moved pxmitpriv->lock after sleep_q.lock release to
> > >>> avoid locks nesting.
> > > 
> > >>>  	rtw_free_xmitframe_queue(pxmitpriv, &psta->sleep_q);
> > >>> +	spin_lock_bh(&psta->sleep_q.lock);
> > >>
> > >> AFAICT this needs to be above the rtw_free_xmitframe_queue() ?
> > > 
> > > as I wrote on the changelog, the sleep_q.lock is already
> > > taken inside rtw_free_xmitframe_queue. If I put the
> > > sleep_q.lock above that function a soft lock occurs when
> > > I disconnect.
> > > 
> > > So I put it just below rtw_free_xmitframe_queue.
> > > 
> > > Things works fine this way.
> > > 
> > > Please tell me if there's a best way to do it.
> > 
> > Hmm I see, this may work, but the sleepq_len access
> > really should be protected by the same lock as the freeing
> > of the queue is without dropping it in between.
> > 
> > That rtw_free_xmitframe_queue() takes the sleep_q.lock
> > then to me that signals that other (higher-level) functions should
> > not take sleep_q.lock at all, since this is then private to the
> > functions operating on the sleep_q.
> > 
> > I've an idea how we we can possibly tackle this, but I'm not sure
> > yet I will try to make some time to look into this tomorrow or
> > the day after.
> 
> I'm just going to go and revert the original change here until you all
> can sort it out :)

that's the best thing for now ;)

> 
> thanks,
> 
> greg k-h

thank you,

fabio