From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lamorak.hansenpartnership.com (lamorak.hansenpartnership.com [198.37.111.173]) (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 EB2542F3626; Thu, 4 Sep 2025 12:39:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.37.111.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756989592; cv=none; b=uNCSx+A1QPWkQpjD8dvRTm1+iMW5KSt3CgkqSnNvgwl+PMl3bbsH9eF3buUBhuklfEPXOARV+oBzlZb+oECMKdFKdsD5UrH9KuEX4PoZrrprPgak0PUMxRSSGJzWiRCWQN51TRIMGpEcEdFMDq+dwAE5h9fORsdZ2+whO2AAIow= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756989592; c=relaxed/simple; bh=WImbDcvNgaOY6gWJtivhJYt6Urfmm/XDBLbKaosswu8=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=UMtmo5foHEcZZW3e0eWixr9Rgcq9Z/gidNB4JP0PXCEDFSBLL794Y/yueZ/ZJ8q8vyexPtAyO4Jy3KS8PQqbhy6uBb+h0ibZWJ0Dzk+otrPsg4nS/a6qD//GD2P2fBBI2kDUBKPyqsINhVaoR4g0Fl2ScjIyKRrwyg45FlIx+0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=paQZS3HY; arc=none smtp.client-ip=198.37.111.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="paQZS3HY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1756989588; bh=WImbDcvNgaOY6gWJtivhJYt6Urfmm/XDBLbKaosswu8=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=paQZS3HYWipc9lv3ukH6ZpiW+DKGOrvzRXOEDKl1liuLQgLV/h+6bBO1Ajk5S2tKn D9/vzLV3i0/GfwjoD5bWRZT9PHd2toCfOgZInMtxdxRxg/qNq0SDpn9P+Z3mtwn7Wy 1bDja2EooAq0mk0/OIC1rulWRV8gGmnqqcNiu+O0= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::a774]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lamorak.hansenpartnership.com (Postfix) with ESMTPSA id 57A121C0012; Thu, 04 Sep 2025 08:39:48 -0400 (EDT) Message-ID: Subject: Re: [PATCH][next] scsi: pm80xx: Avoid -Wflex-array-member-not-at-end warning From: James Bottomley To: John Garry , "Gustavo A. R. Silva" , Jack Wang , "Martin K. Petersen" Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Date: Thu, 04 Sep 2025 08:39:47 -0400 In-Reply-To: <7b60681e-a964-494a-a6fa-aba00086b7f7@oracle.com> References: <7b60681e-a964-494a-a6fa-aba00086b7f7@oracle.com> Autocrypt: addr=James.Bottomley@HansenPartnership.com; prefer-encrypt=mutual; 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 8mT2Eh9SkH+YVOmaKsajgZgrBxA7fWmGoxXswEVxJIFj3vW7yNc0C5HaUdYa5iGOMs4kg2ht4s7yy7NRQuh7BifWjo6BQ6k4S1H+6axZucxhSV1L6zN9d+lr3Xo/vy1unzA== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2025-09-04 at 07:52 +0100, John Garry wrote: > On 03/09/2025 19:44, Gustavo A. R. Silva wrote: > > diff --git a/drivers/scsi/pm8001/pm8001_hwi.h > > b/drivers/scsi/pm8001/pm8001_hwi.h > > index fc2127dcb58d..7dc7870a8f86 100644 > > --- a/drivers/scsi/pm8001/pm8001_hwi.h > > +++ b/drivers/scsi/pm8001/pm8001_hwi.h > > @@ -339,8 +339,10 @@ struct ssp_completion_resp { > > =C2=A0=C2=A0 __le32 status; > > =C2=A0=C2=A0 __le32 param; > > =C2=A0=C2=A0 __le32 ssptag_rescv_rescpad; > > - struct ssp_response_iu=C2=A0 ssp_resp_iu; > > =C2=A0=C2=A0 __le32 residual_count; > > + > > + /* Must be last --ends in a flexible-array member. */ > > + struct ssp_response_iu=C2=A0 ssp_resp_iu; >=20 > this is a HW structure, right? I did not think that it is ok to > simply re-order them... Agreed, this is a standards defined information unit corresponding to an on the wire data structure. The patch is clearly wrong. That being said, the three things the flexible member can contain are no data, response data or sense data. None of them has a residual count at the beginning and, indeed, this field is never referred to in the driver, so it looks like it can simply be deleted to fix the warning. That being said, this pattern of adding fields after flexible members to represent data that's common to all content types of the union is not unknown in SCSI so if you want to enable this warning, what are we supposed to do when we encounter a genuine use case? Regards, James