linux-kernel - Re: [Outreachy kernel] [PATCH 4/4] staging: rtl8723bs: Change the type and use of a variable

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Message-ID: <10115279.QsZogQpAqX@localhost.localdomain>
Date:   Sat, 10 Apr 2021 13:23:21 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     outreachy-kernel@...glegroups.com, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, julia.lawall@...ia.fr
Subject: Re: [Outreachy kernel] [PATCH 4/4] staging: rtl8723bs: Change the type and use of a variable

On Saturday, April 10, 2021 1:03:34 PM CEST Greg KH wrote:
> On Sat, Apr 10, 2021 at 12:58:06PM +0200, Fabio M. De Francesco wrote:
> > On Saturday, April 10, 2021 12:31:27 PM CEST Greg KH wrote:
> > > On Sat, Apr 10, 2021 at 11:56:48AM +0200, Fabio M. De Francesco 
wrote:
> > > > On Saturday, April 10, 2021 11:31:16 AM CEST Greg KH wrote:
> > > > > On Sat, Apr 10, 2021 at 11:22:32AM +0200, Fabio M. De Francesco
> > 
> > wrote:
> > > > > > Change the type of fw_current_in_ps_mode from u8 to bool,
> > > > > > because
> > > > > > it is used everywhere as a bool and, accordingly, it should be
> > > > > > declared as a bool. Shorten the controlling
> > > > > > expression of an 'if' statement.
> > > > > > 
> > > > > > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
> > > > > > ---
> > > > > > 
> > > > > >  drivers/staging/rtl8723bs/hal/hal_intf.c        | 2 +-
> > > > > >  drivers/staging/rtl8723bs/include/rtw_pwrctrl.h | 2 +-
> > > > > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/staging/rtl8723bs/hal/hal_intf.c
> > > > > > b/drivers/staging/rtl8723bs/hal/hal_intf.c index
> > > > > > 96fe172ced8d..8dc4dd8c6d4c 100644
> > > > > > --- a/drivers/staging/rtl8723bs/hal/hal_intf.c
> > > > > > +++ b/drivers/staging/rtl8723bs/hal/hal_intf.c
> > > > > > @@ -348,7 +348,7 @@ void rtw_hal_dm_watchdog(struct adapter
> > > > > > *padapter)
> > > > > > 
> > > > > >  void rtw_hal_dm_watchdog_in_lps(struct adapter *padapter)
> > > > > >  {
> > > > > > 
> > > > > > -	if (adapter_to_pwrctl(padapter)->fw_current_in_ps_mode ==
> > 
> > true)
> > 
> > > > {
> > > > 
> > > > > > +	if (adapter_to_pwrctl(padapter)->fw_current_in_ps_mode) {
> > > > > > 
> > > > > >  		if (padapter->HalFunc.hal_dm_watchdog_in_lps)
> > > > > >  		
> > > > > >  			padapter-
> > > > >
> > > > >HalFunc.hal_dm_watchdog_in_lps(padapter); /* this
> > > > >
> > > > > >  			function caller is in interrupt 
context
> > > > 
> > > > */>
> > > > 
> > > > > >  	}
> > > > > > 
> > > > > > diff --git a/drivers/staging/rtl8723bs/include/rtw_pwrctrl.h
> > > > > > b/drivers/staging/rtl8723bs/include/rtw_pwrctrl.h index
> > > > > > 0a48f1653be5..0767dbb84199 100644
> > > > > > --- a/drivers/staging/rtl8723bs/include/rtw_pwrctrl.h
> > > > > > +++ b/drivers/staging/rtl8723bs/include/rtw_pwrctrl.h
> > > > > > @@ -203,7 +203,7 @@ struct pwrctrl_priv {
> > > > > > 
> > > > > >  	u8 LpsIdleCount;
> > > > > >  	u8 power_mgnt;
> > > > > >  	u8 org_power_mgnt;
> > > > > > 
> > > > > > -	u8 fw_current_in_ps_mode;
> > > > > > +	bool fw_current_in_ps_mode;
> > > > > > 
> > > > > >  	unsigned long	DelayLPSLastTimeStamp;
> > > > > >  	s32		pnp_current_pwr_state;
> > > > > >  	u8 pnp_bstop_trx;
> > > > > 
> > > > > If this is only checked, how can it ever be true?  Who ever sets
> > > > > this
> > > > > value?
> > > > 
> > > > You're right. It is not set, therefore the "if" control expression
> > > > cannot ever be "true".
> > > > 
> > > > Can I delete this statement in a new patch? Or you prefer I send
> > > > the
> > > > whole series again with this change in patch 4/4?
> > > 
> > > Just delete the variable from the structure entirely and when it is
> > > used.
> > 
> > I've read the code of the function whom that 'if' statement belongs to.
> > This function takes a pointer whose name is 'padapter' and this is has
> > global scope. I think that since fw_current_in_ps_mode is dereferenced
> > by the function adapter_to_pwrctl(padapter) it can and is indeed
> > initialized and modified in some other files of the driver.
> 
> Where does that happen, and why did the build not break when you changed
> the variable name?  
>
The build didn't break because I changed the name of that variable 
everywhere it is used in the driver. This patch is against all the affected 
files of each subdirectory of staging/rtl8723bs.
>
> Is the whole variable assigned to a specific
> location in memory in the device?  Where is it initialized?
>
That variable has global scope and is assigned at least in:

drivers/staging/rtl8723bs/core/rtw_pwrctrl.c:368:                       
pwrpriv->fw_current_in_ps_mode = false;

drivers/staging/rtl8723bs/core/rtw_pwrctrl.c:380:                       
pwrpriv->fw_current_in_ps_mode = true;

drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c:433:  
adapter_to_pwrctl(padapter)->fw_current_in_ps_mode = false;

drivers/staging/rtl8723bs/core/rtw_pwrctrl.c:981:       
pwrctrlpriv->fw_current_in_ps_mode = false;

Thanks,

Fabio
> 
> > That's why I'll leave the if statement as is now. If I am wrong there's
> > time to change it later in a future patch.
> 
> Don't change obviously wrong code, we can clean it up properly :)
> 
> thanks,
> 
> greg k-h