linux-kernel - Re: [PATCH 2/3] staging: r8188eu: simplify c2h_evt

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Date:   Mon, 30 Aug 2021 11:06:04 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Phillip Potter <phil@...lpotter.co.uk>
Cc:     gregkh@...uxfoundation.org, straube.linux@...il.com,
        fmdefrancesco@...il.com, Larry.Finger@...inger.net,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] staging: r8188eu: simplify c2h_evt_hdl function

On 8/30/21 2:18 AM, Phillip Potter wrote:
> On Sun, Aug 29, 2021 at 02:54:14PM +0300, Pavel Skripkin wrote:
>> On 8/29/21 12:24 AM, Phillip Potter wrote:
>> > Simplify c2h_evt_hdl function by removing majority of its code. The
>> > function always returns _FAIL anyway, due to the wrapper function it
>> > calls always returning _FAIL. For this reason, it is better to just
>> > return _FAIL directly.
>> > 
>> > Leave the call to c2h_evt_read in place, as without it, event handling
>> > semantics of the driver would be changed, despite nothing actually being
>> > done with the event.
>> > 
>> > Signed-off-by: Phillip Potter <phil@...lpotter.co.uk>
>> > ---
>> >   drivers/staging/r8188eu/core/rtw_cmd.c | 21 +++------------------
>> >   1 file changed, 3 insertions(+), 18 deletions(-)
>> > 
>> > diff --git a/drivers/staging/r8188eu/core/rtw_cmd.c b/drivers/staging/r8188eu/core/rtw_cmd.c
>> > index ce73ac7cf973..b520c6b43c03 100644
>> > --- a/drivers/staging/r8188eu/core/rtw_cmd.c
>> > +++ b/drivers/staging/r8188eu/core/rtw_cmd.c
>> > @@ -1854,27 +1854,12 @@ u8 rtw_c2h_wk_cmd(struct adapter *padapter, u8 *c2h_evt)
>> >   static s32 c2h_evt_hdl(struct adapter *adapter, struct c2h_evt_hdr *c2h_evt, c2h_id_filter filter)
>> >   {
>> > -	s32 ret = _FAIL;
>> >   	u8 buf[16];
>> > -	if (!c2h_evt) {
>> > -		/* No c2h event in cmd_obj, read c2h event before handling*/
>> > -		if (c2h_evt_read(adapter, buf) == _SUCCESS) {
>> > -			c2h_evt = (struct c2h_evt_hdr *)buf;
>> > +	if (!c2h_evt)
>> > +		c2h_evt_read(adapter, buf);
>> > -			if (filter && !filter(c2h_evt->id))
>> > -				goto exit;
>> > -
>> > -			ret = rtw_hal_c2h_handler(adapter, c2h_evt);
>> > -		}
>> > -	} else {
>> > -		if (filter && !filter(c2h_evt->id))
>> > -			goto exit;
>> > -
>> > -		ret = rtw_hal_c2h_handler(adapter, c2h_evt);
>> > -	}
>> > -exit:
>> > -	return ret;
>> > +	return _FAIL;
>> 
>> 
>> Hi, Phillip!
>> 
>> 
>> Do we really need to return _FAIL every time? The only one caller of
>> c2h_evt_hdl() does not rely on it's return value. Shouldn't we make this
>> function return void to simplify the code?
> 
> Dear Pavel,
> 
> Thanks for the review. Good point on the return type, I'll publish a v2
> series.
> 
>> 
>> 
>> BTW, this function does nothing now, as I understand. It reads to local
>> buffer and returns. I think, it can be removed
>> 
>> 
>> 
>> >   }
>> >   static void c2h_wk_callback(struct work_struct *work)
>> > 
> 
> Not sure if you're referring to c2h_wk_callback or c2h_evt_hdl, but
> either way, they both call (indirectly or otherwise) c2h_evt_read and
> c2h_evt_clear as well as rtw_c2h_wk_cmd in the case of c2h_wk_callback.
> To just delete them wholesale therefore would be unsafe I think, due to
> the effect on event semantics.
> 
> Certainly, it is possible to handle this c2h stuff by just reading from
> register and ignoring though - another series is a better place for that
> though I think. Admittedly, I may be talking nonsense here :-)
> 

I was referring to c2h_evt_hdl. I missed, that c2h_evt_read() writes to 
register, sorry :)





With regards,
Pavel Skripkin