From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from omta40.uswest2.a.cloudfilter.net (omta40.uswest2.a.cloudfilter.net [35.89.44.39]) (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 7B80DEACD for ; Fri, 29 Aug 2025 16:17:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=35.89.44.39 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756484252; cv=none; b=U5SYhRBWyauh6qmqMRqXGiCsRfNFs98OiSpUYwV0zdZqOh1VyN5R3EQj+/PN0LJbw2HZpK/0YqhSDilC72wTiBAaM2AWaXYDhmJQMW08usumdPwyw89pULt2uGkyMwULlpFhTYVWMLZelz+FMTszDY6B9yGnll5tbRnQ2jnbAns= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756484252; c=relaxed/simple; bh=KLt4H1dAsH4m3W8wq5f1JTt1awfasu+AhMOuE6RzBOs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aXmFblvBpZLBzYu1zKJiWP+cqWo6MyuOQr58eTOqUjtYWaFJauPJweZcYLoVVzsG5r8tyvvU7593e7mCais+EhPVWMiK2p8mZloTSY2PwjYY+Oq7vXsdDU+ZvBOLUf29pOHznHnuy7UKc92CadhQbMvbbJEye6fUyAob0jmiV2o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=embeddedor.com; spf=pass smtp.mailfrom=embeddedor.com; dkim=pass (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b=SJByZQBy; arc=none smtp.client-ip=35.89.44.39 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=embeddedor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=embeddedor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b="SJByZQBy" Received: from eig-obgw-5002b.ext.cloudfilter.net ([10.0.29.226]) by cmsmtp with ESMTPS id s0gKus0SW17jAs1n2ugY6R; Fri, 29 Aug 2025 16:17:24 +0000 Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with ESMTPS id s1n0uNEhHrnsYs1n1uDXQ2; Fri, 29 Aug 2025 16:17:23 +0000 X-Authority-Analysis: v=2.4 cv=OLkn3TaB c=1 sm=1 tr=0 ts=68b1d293 a=1YbLdUo/zbTtOZ3uB5T3HA==:117 a=DR2cKC/DEnBA9KqqjaPhpA==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=7T7KSl7uo7wA:10 a=VwQbUJbxAAAA:8 a=TsAxZPKnxnV8R9QPSkIA:9 a=QEXdDO2ut3YA:10 a=xYX6OU9JNrHFPr8prv8u:22 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=jd58pSIsv1e0sCZpmSVms3HbnYFises5DmnzMNo/SI0=; b=SJByZQByYNRohejkbnYICwqHak TIIvcUIMXBt+mCHl5aDfJpFVL2rFm94Zbg4XvBhPkyDWY9G9Rhy3WX89aFk1Tb5aYDVNMrSb3+T9c 1COE02dHTnZfIYvPFOpPH6h9ICud9ZDpbhtKwvE9dQEyrhD7V0RrR5+eMg9P97Dh9yhs7mEfDWrQs U/4EHXQI0qeYBMVFeVfKgcwHzh1doY3aFrkNs1trvHtUlmgtB6yA+ZeEEXfh3lclzlGq1tC5yWBkt KSw/AIdTghFQhFKZDbDiM5BBFbtqmTRLnRIGKI+8GvSBYOGjxgz4M4rD6guhHirdVGQ1ZghakoL7p v5DdgLcw==; Received: from static-243-216-117-93.thenetworkfactory.nl ([93.117.216.243]:49788 helo=[10.28.229.44]) by gator4166.hostgator.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.98.1) (envelope-from ) id 1us1mz-00000004L3i-0KqT; Fri, 29 Aug 2025 11:17:21 -0500 Message-ID: Date: Fri, 29 Aug 2025 18:17:03 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2][next] hyperv: Avoid a hundred -Wflex-array-member-not-at-end warnings To: Michael Kelley , "Gustavo A. R. Silva" , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui Cc: "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-hardening@vger.kernel.org" References: Content-Language: en-US From: "Gustavo A. R. Silva" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 93.117.216.243 X-Source-L: No X-Exim-ID: 1us1mz-00000004L3i-0KqT X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: static-243-216-117-93.thenetworkfactory.nl ([10.28.229.44]) [93.117.216.243]:49788 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 2 X-Org: HG=hgshared;ORG=hostgator; X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-CMAE-Envelope: MS4xfJhwT1kxP/UHYQNa961YY36H/D9Urx1c3NC6aRulD6ywy7KxnbN/gwE1jFl1u4rjpMikwZrSQp19I11qzuBpGOW00NoW1MAU+jXFKmacUbiYUwjvN2Ej Q26N64aUDhXUiACi55yPepmtvkkwroKrpjZ6z9ys9lDekMLtlRTDIgo9dGGkbiu1Tgo832Z734DWukqgdy0j9keFtsYOrO/cSdYtau6z07UxovdD4DNkomkA On 8/29/25 18:07, Michael Kelley wrote: > From: Gustavo A. R. Silva Sent: Friday, August 29, 2025 4:44 AM >> >> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are >> getting ready to enable it, globally. >> >> Use the new TRAILING_OVERLAP() helper to fix 159 of the following type >> of warnings: >> >> 159 ./include/linux/hyperv.h:711:38: warning: structure containing a flexible array >> member is not at the end of another structure [-Wflex-array-member-not-at-end] >> >> This helper creates a union between a flexible-array member (FAM) >> and a set of members that would otherwise follow it. This overlays >> the trailing members onto the FAM while preserving the original >> memory layout. >> >> Also, move `struct vmbus_close_msg close_msg;` at the end of >> `struct vmbus_channel`, as `struct vmbus_channel_msginfo,` ends >> in a flexible array member. >> >> Signed-off-by: Gustavo A. R. Silva >> -- >> Changes in v2: >> - Fix subject line. >> >> v1: >> - Link: https://lore.kernel.org/linux-hardening/aLGSDpi4xDjUUYVm@kspp/ >> >> include/linux/hyperv.h | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h >> index a59c5c3e95fb..efdd570669fa 100644 >> --- a/include/linux/hyperv.h >> +++ b/include/linux/hyperv.h >> @@ -708,8 +708,9 @@ struct vmbus_channel_msginfo { >> }; >> >> struct vmbus_close_msg { >> - struct vmbus_channel_msginfo info; > > It turns out that this field of struct vmbus_close_msg is never used. > It dates back to 2011, so maybe somewhere along the way it stopped > being used, but struct vmbus_close_msg was left unchanged. > > So a better solution to the "flex-array-member-not-at-end" issue is > to eliminate this structure entirely, and use struct > vmbus_channel_close_channel directly in the one place where > struct vmbus_close_msg is currently used. I've done a quick test of > this change and I don't see any problems. > > I'll submit a separate patch with my proposed change, and this > patch can be dropped. Does that work? Yes, please. Go for it. :) Thanks! -Gustavo