From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from msg-4.mailo.com (msg-4.mailo.com [213.182.54.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 541512F30 for ; Thu, 17 Nov 2022 13:21:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1668691261; bh=N9pDZUTKVWmcCMLDo7BDwGJ71H9koLDvz0Lw4Lwo6pQ=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:In-Reply-To; b=Y/pQXmvAbDfPJC2BXP/MP7acs7sOO8XEv4QnGYFRLasTAsRNAVyOBPvWGFJboPdv1 bsdK/WJDPci3NIBO7bOMHQcuPGMO4G2btrPw0UAjmyCoE4XRmAvLb2nsmZX8Up38bq Cm9CZG8+rP84Ly+46oaOkiuzS1UilPVpLtBcPys4= Received: by b-6.in.mailobj.net [192.168.90.16] with ESMTP via ip-206.mailobj.net [213.182.55.206] Thu, 17 Nov 2022 14:21:00 +0100 (CET) X-EA-Auth: UijATNLUhksPhklMt0RnzdQPPKNk33NwzW2kr3ZK5xnRR3INQDOR1bX/0JRfebmWS/jsblxg8mESktDJkPEfVbXPwqGPnOpG Date: Thu, 17 Nov 2022 18:50:55 +0530 From: Deepak R Varma To: Greg Kroah-Hartman Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, gustavoars@kernel.org Subject: Re: [PATCH] staging: wlan-ng: Replace zero-length arrays with DECLARE_FLEX_ARRAY() helper Message-ID: References: Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Nov 17, 2022 at 01:54:49PM +0100, Greg Kroah-Hartman wrote: > On Thu, Nov 17, 2022 at 03:48:45PM +0530, Deepak R Varma wrote: > > The code currently uses C90 standard extension based zero length arrays. > > The zero length array member also happens to be the only member of the > > structs. Such zero length array declarations are deprecated and the > > new C99 standard extension of flexible array declarations are to be > > used instead. > > > > The DECLARE_FLEX_ARRAY() helper allows for a flexible array member as > > the only member in a structure. Refer to these links [1], [2] for > > details. > > > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > > [2] https://lkml.kernel.org/r/YxKY6O2hmdwNh8r8@work > > > > Issue identified using Coccinelle. > > > > Signed-off-by: Deepak R Varma > > --- > > > > Notes: > > 1. Proposed change is compile tested only. > > 2. Solution feedback from gustavoars@kernel.org > > > > > > drivers/staging/wlan-ng/hfa384x.h | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/staging/wlan-ng/hfa384x.h b/drivers/staging/wlan-ng/hfa384x.h > > index 0611e37df6ac..3a1edcb43e07 100644 > > --- a/drivers/staging/wlan-ng/hfa384x.h > > +++ b/drivers/staging/wlan-ng/hfa384x.h > > @@ -960,15 +960,15 @@ struct hfa384x_pdr_nicid { > > } __packed; > > > > struct hfa384x_pdr_refdac_measurements { > > - u16 value[0]; > > + DECLARE_FLEX_ARRAY(u16, value); > > } __packed; > > Why? This structure is never used anywhere, right? So why is this > needed to be changed and not just removed entirely? Same for the other > structures in this patch. Hello Greg, I am unable to confirm that these structures are truly not needed in the absence if a real device based testing. I could only validate that using the compile build and driver loading. This change that I am proposing in the interim would enable the compiler to protect the structure from addition of a new member below the zero length array. If there is a way to confirm that the structures are indeed not needed, I can revise the patch and send the cleanup accordingly. Please suggest. Thank you, ./drv > > thanks, > > greg k-h