linux-kernel - Re: [PATCH] staging: wlan-ng: Use flexible-array for one / zero-length arrays

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Message-ID: <Y1vq5QdBn1oQUqij@ubunlion>
Date:   Fri, 28 Oct 2022 20:14:53 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     outreachy@...ts.linux.dev,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: wlan-ng: Use flexible-array for one /
 zero-length arrays

On Fri, Oct 28, 2022 at 05:36:41PM +0300, Dan Carpenter wrote:
> On Fri, Oct 28, 2022 at 06:08:13PM +0530, Deepak R Varma wrote:
> > Flexible-array member should be used instead of one or zero member to
> > meet the need for having a dynamically sized trailing elements in a
> > structure. Refer to links [1] and [2] for detailed guidance on this
> > suggestion.
> >
> > [1] https://en.wikipedia.org/wiki/Flexible_array_member
> > [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
> >
> > Issue identified using coccicheck.
> >
> > Signed-off-by: Deepak R Varma <drv@...lo.com>
> > ---
> >  drivers/staging/wlan-ng/p80211mgmt.h  | 8 ++++----
> >  drivers/staging/wlan-ng/p80211types.h | 2 +-
> >  2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/staging/wlan-ng/p80211mgmt.h b/drivers/staging/wlan-ng/p80211mgmt.h
> > index 1ef30d3f3159..d6fe52de2c8f 100644
> > --- a/drivers/staging/wlan-ng/p80211mgmt.h
> > +++ b/drivers/staging/wlan-ng/p80211mgmt.h
> > @@ -229,14 +229,14 @@ struct wlan_ie {
> >  struct wlan_ie_ssid {
> >  	u8 eid;
> >  	u8 len;
> > -	u8 ssid[1];		/* may be zero, ptrs may overlap */
> > +	u8 ssid[];		/* may be zero, ptrs may overlap */
> >  } __packed;
>
> When you're writing this change look at where struct wlan_ie_ssid is
> used.  It's included in five different structs:
>
> 	struct wlan_ie_ssid *ssid;
>
> But none of those *ssid pointers are used.  So instead of doing this
> just delete the wlan_ie_ssid struct and delete every reference to it.
> Send that as a patch by itself and then repeat that process for the next
> struct.

Thank you Dan. I had the same observation, but was not sure if that clean up
should be included as part of current patch scope. Now I will, as you advised.

Also, there are a few function declarations that I do not think are used in the
code anywhere.
   File: drivers/staging/wlan-ng/p80211mgmt.h
   Line number : 500 through 519

Can you please comment if it is safe to remove these functions and include this
clean-up as well in the proposed patch?

Thank you,
./drv

>
> regards,
> dan carpenter
>