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bh=ovsE9udiZpMaS9PEteVJgFoXfb07sOex+i+abUOfeJ4=; b=ZwHfEsDC1iblRec/fsNpE4gY5JZPTHD83/7W+XA7w4IHaNqjw96Cz0y9arTX1FEc+lrlZh JZJalxs4n97tnjlgVHA/iyNfdEpbTV2Ev1UDZ9tXG9y77icH21DmJlmhk+5byTA9yX72iB X+dMpzz0VF1Iu+a+vDXTwSPsNJPs5lw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-589-kZr448cAOHW1_YHMzLd6RQ-1; Wed, 30 Sep 2020 13:19:48 -0400 X-MC-Unique: kZr448cAOHW1_YHMzLd6RQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0CB6B1868413; Wed, 30 Sep 2020 17:19:47 +0000 (UTC) Received: from [10.3.112.131] (ovpn-112-131.phx2.redhat.com [10.3.112.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7946A5C1CF; Wed, 30 Sep 2020 17:19:40 +0000 (UTC) Subject: Re: [PATCH 2/4] nbd: silence maybe-uninitialized warnings To: Christian Borntraeger , qemu-devel@nongnu.org References: <20200930155859.303148-1-borntraeger@de.ibm.com> <20200930155859.303148-3-borntraeger@de.ibm.com> From: Eric Blake Autocrypt: addr=eblake@redhat.com; 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Message-ID: Date: Wed, 30 Sep 2020 12:19:39 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200930155859.303148-3-borntraeger@de.ibm.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="gBcRPNbWyG3oYS7FRRw8SObPnNVMzU2Tg" Received-SPF: pass client-ip=216.205.24.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/30 00:26:33 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.469, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Kevin Wolf , qemu-block@nongnu.org, "Dr . David Alan Gilbert" , Max Reitz , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --gBcRPNbWyG3oYS7FRRw8SObPnNVMzU2Tg Content-Type: multipart/mixed; boundary="x3NmCuZDgmjDbWJnVs8xwmZH9gKbeKrPx"; protected-headers="v1" From: Eric Blake To: Christian Borntraeger , qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, "Dr . David Alan Gilbert" , Stefan Hajnoczi , Fam Zheng , Kevin Wolf , Max Reitz Message-ID: Subject: Re: [PATCH 2/4] nbd: silence maybe-uninitialized warnings References: <20200930155859.303148-1-borntraeger@de.ibm.com> <20200930155859.303148-3-borntraeger@de.ibm.com> In-Reply-To: <20200930155859.303148-3-borntraeger@de.ibm.com> --x3NmCuZDgmjDbWJnVs8xwmZH9gKbeKrPx Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 9/30/20 10:58 AM, Christian Borntraeger wrote: > gcc 10 from Fedora 32 gives me: >=20 > Compiling C object libblock.fa.p/nbd_server.c.o > ../nbd/server.c: In function =E2=80=98nbd_co_client_start=E2=80=99: > ../nbd/server.c:625:14: error: =E2=80=98namelen=E2=80=99 may be used unin= itialized in this function [-Werror=3Dmaybe-uninitialized] > 625 | rc =3D nbd_negotiate_send_info(client, NBD_INFO_NAME, nam= elen, name, > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~= ~~~~~~~~~ > 626 | errp); > | ~~~~~ > ../nbd/server.c:564:14: note: =E2=80=98namelen=E2=80=99 was declared here > 564 | uint32_t namelen; > | ^~~~~~~ > cc1: all warnings being treated as errors >=20 > As I cannot see how this can happen, let uns silence the warning. gcc is smart enough to see that nbd_opt_read_name(... &namelen), which is the only use of namelen between declaration and use, does not always initialize namelen; but fails to see we also exit this function early in the same conditions when nbd_opt_read_name left namelen uninit. The workaround is fine. Reviewed-by: Eric Blake I'm happy for this to go in through the trivial tree, but I'll also queue it on my NBD tree if that is ready first. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --x3NmCuZDgmjDbWJnVs8xwmZH9gKbeKrPx-- --gBcRPNbWyG3oYS7FRRw8SObPnNVMzU2Tg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAl90visACgkQp6FrSiUn Q2qS9wf+Jl/ssRsPdWQMlAJli2Xn1TpGmLhb1o/eEoKzIbjKHbiaCzlbApDDO2Ts /hshRBRNda6R3LMRVhzM4TbPI1x0avdzFI6HMxVwF1/1D7GtiGlZFZErluZKlpCQ p0YuefqA5d7Y35Ep0kueYxHgxnSmiTwkLsoqVYKAWmYqBtbjUHxGVH6AvKz/hqzJ 3vEBaOIATFPL7UGHCgFUfK7dqN1IO3r33pkwqqWTnak4kakBZ7mlAxNNAwIuq5Am gt9sNO1G+qUDWvKjtF6r8ZaS9DOvJg4aYpjxLwnjQBBpcihxu/oQGo74OGdQMpPJ 4AbEXhvl4qbiJf9kgKM+a11nkMQQzw== =kUcB -----END PGP SIGNATURE----- --gBcRPNbWyG3oYS7FRRw8SObPnNVMzU2Tg--