From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C684C63777 for ; Thu, 3 Dec 2020 09:51:23 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A5D3620C56 for ; Thu, 3 Dec 2020 09:51:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5D3620C56 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.43285.77840 (Exim 4.92) (envelope-from ) id 1kklGY-0005V3-9g; Thu, 03 Dec 2020 09:51:10 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 43285.77840; Thu, 03 Dec 2020 09:51:10 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kklGY-0005Uw-60; Thu, 03 Dec 2020 09:51:10 +0000 Received: by outflank-mailman (input) for mailman id 43285; Thu, 03 Dec 2020 09:51:08 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kklGW-0005Ur-MY for xen-devel@lists.xenproject.org; Thu, 03 Dec 2020 09:51:08 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 6ff6a737-147b-45e7-94b6-8e5085aac97a; Thu, 03 Dec 2020 09:51:04 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C6796AD41; Thu, 3 Dec 2020 09:51:03 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 6ff6a737-147b-45e7-94b6-8e5085aac97a X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1606989063; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qbY9qgML224Q9oA2ZDLIgpLcJl5U9LYu8RN1jSojU6I=; b=cNsUJivVR1wmG+ZSQGLbL8JIyzij4+db4po29hRFxwl/7ze8jzzlhNInJD8BxHEJ70CP7B 2eT+2lsRObdHSU8lBmv647DN8iit1L7f2IU1GPv+dru6VQ45lPxFZiF0g0chkJu/WhhnxZ wxH18W0m2RzH3WXN4+SZJN8CHdP3syI= To: Jan Beulich Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20201201082128.15239-1-jgross@suse.com> <20201201082128.15239-10-jgross@suse.com> <4ddee6b8-36bb-63ae-2221-78c1768b3355@suse.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Subject: Re: [PATCH v2 09/17] xen/hypfs: move per-node function pointers into a dedicated struct Message-ID: <5e0a7a74-1d00-7f9f-e595-27f441c5c200@suse.com> Date: Thu, 3 Dec 2020 10:51:02 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <4ddee6b8-36bb-63ae-2221-78c1768b3355@suse.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="iUmYVvk9AcNu7UpvuoAWd0MLEaieoAgsE" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --iUmYVvk9AcNu7UpvuoAWd0MLEaieoAgsE Content-Type: multipart/mixed; boundary="wWa1WkU4HwNLL3kYQ6SaCgMectahfLiGa"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: Jan Beulich Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org Message-ID: <5e0a7a74-1d00-7f9f-e595-27f441c5c200@suse.com> Subject: Re: [PATCH v2 09/17] xen/hypfs: move per-node function pointers into a dedicated struct References: <20201201082128.15239-1-jgross@suse.com> <20201201082128.15239-10-jgross@suse.com> <4ddee6b8-36bb-63ae-2221-78c1768b3355@suse.com> In-Reply-To: <4ddee6b8-36bb-63ae-2221-78c1768b3355@suse.com> --wWa1WkU4HwNLL3kYQ6SaCgMectahfLiGa Content-Type: multipart/mixed; boundary="------------E8F0A1D174FD905D8CBDB0A1" Content-Language: en-US This is a multi-part message in MIME format. --------------E8F0A1D174FD905D8CBDB0A1 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 03.12.20 10:12, Jan Beulich wrote: > On 03.12.2020 09:47, J=C3=BCrgen Gro=C3=9F wrote: >> On 02.12.20 16:36, Jan Beulich wrote: >>> On 01.12.2020 09:21, Juergen Gross wrote: >>>> static int hypfs_write(struct hypfs_entry *entry, >>>> XEN_GUEST_HANDLE_PARAM(void) uaddr, unsign= ed long ulen) >>> >>> As a tangent, is there a reason these write functions don't take >>> handles of "const void"? (I realize this likely is nothing that >>> wants addressing right here.) >> >> Uh, this is harder than I thought. >> >> guest_handle_cast() doesn't handle const guest handle types currently:= >> >> hypfs.c:447:58: error: unknown type name =E2=80=98const_void=E2=80=99;= did you mean =E2=80=98const=E2=80=99? >> ret =3D hypfs_write(entry, guest_handle_cast(arg3, const_vo= id), >> arg4); >> ^ >> /home/gross/xen/unstable/xen/include/xen/guest_access.h:26:5: note: in= >> definition of macro =E2=80=98guest_handle_cast=E2=80=99 >> type *_x =3D (hnd).p; \ >> ^~~~ >> >> Currently my ideas would be to either: >> >> - add a new macro for constifying a guest handle (type -> const_type) >> - add a new macro for casting a guest handle to a const_type >> - add typedefs for the const_* types (typedef const x const_x) >> - open code the cast >> >> Or am I missing an existing variant? >=20 > I don't think you are. Both of your first two suggestions look good > to me - ultimately we may want to have both anyway, eventually. For > its (presumed) type safety I may have a slight preference for > option 1, albeit afaics guest_handle_cast() doesn't allow > conversion between arbitrary types either (only to/from void). >=20 > It's quite unfortunate that this requires an explicit cast in the > first place, but what do you do. Right. I'm going with variant 2, as variant 1 is not really easy to achieve without specifying the basic type as a macro parameter - which will basically be variant 2. Juergen --------------E8F0A1D174FD905D8CBDB0A1 Content-Type: application/pgp-keys; name="OpenPGP_0xB0DE9DD628BF132F.asc" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="OpenPGP_0xB0DE9DD628BF132F.asc" -----BEGIN PGP PUBLIC KEY BLOCK----- xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOBy= cWx w3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJvedYm8O= f8Z d621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJNwQpd369y= 9bf IhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvxXP3FAp2pkW0xq= G7/ 377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEBAAHNHEp1ZXJnZW4gR= 3Jv c3MgPGpnQHBmdXBmLm5ldD7CwHkEEwECACMFAlOMcBYCGwMHCwkIBwMCAQYVCAIJCgsEFgIDA= QIe AQIXgAAKCRCw3p3WKL8TL0KdB/93FcIZ3GCNwFU0u3EjNbNjmXBKDY4FUGNQH2lvWAUy+dnyT= hpw dtF/jQ6j9RwE8VP0+NXcYpGJDWlNb9/JmYqLiX2Q3TyevpB0CA3dbBQp0OW0fgCetToGIQrg0= MbD 1C/sEOv8Mr4NAfbauXjZlvTj30H2jO0u+6WGM6nHwbh2l5O8ZiHkH32iaSTfN7Eu5RnNVUJbv= oPH Z8SlM4KWm8rG+lIkGurqqu5gu8q8ZMKdsdGC4bBxdQKDKHEFExLJK/nRPFmAuGlId1E3fe10v= 5QL +qHI3EIPtyfE7i9Hz6rVwi7lWKgh7pe0ZvatAudZ+JNIlBKptb64FaiIOAWDCx1SzR9KdWVyZ= 2Vu IEdyb3NzIDxqZ3Jvc3NAc3VzZS5jb20+wsB5BBMBAgAjBQJTjHCvAhsDBwsJCAcDAgEGFQgCC= QoL BBYCAwECHgECF4AACgkQsN6d1ii/Ey/HmQf/RtI7kv5A2PS4RF7HoZhPVPogNVbC4YA6lW7Dr= Wf0 teC0RR3MzXfy6pJ+7KLgkqMlrAbN/8Dvjoz78X+5vhH/rDLa9BuZQlhFmvcGtCF8eR0T1v0nC= /nu AFVGy+67q2DH8As3KPu0344TBDpAvr2uYM4tSqxK4DURx5INz4ZZ0WNFHcqsfvlGJALDeE0Lh= ITT d9jLzdDad1pQSToCnLl6SBJZjDOX9QQcyUigZFtCXFst4dlsvddrxyqT1f17+2cFSdu7+ynLm= XBK 7abQ3rwJY8SbRO2iRulogc5vr/RLMMlscDAiDkaFQWLoqHHOdfO9rURssHNN8WkMnQfvUewRz= 80h SnVlcmdlbiBHcm9zcyA8amdyb3NzQG5vdmVsbC5jb20+wsB5BBMBAgAjBQJTjHDXAhsDBwsJC= AcD AgEGFQgCCQoLBBYCAwECHgECF4AACgkQsN6d1ii/Ey8PUQf/ehmgCI9jB9hlgexLvgOtf7PJn= FOX gMLdBQgBlVPO3/D9R8LtF9DBAFPNhlrsfIG/SqICoRCqUcJ96Pn3P7UUinFG/I0ECGF4EvTE1= jnD kfJZr6jrbjgyoZHiw/4BNwSTL9rWASyLgqlA8u1mf+c2yUwcGhgkRAd1gOwungxcwzwqgljf0= N51 N5JfVRHRtyfwq/ge+YEkDGcTU6Y0sPOuj4Dyfm8fJzdfHNQsWq3PnczLVELStJNdapwPOoE+l= otu fe3AM2vAEYJ9rTz3Cki4JFUsgLkHFqGZarrPGi1eyQcXeluldO3m91NK/1xMI3/+8jbO0tsn1= tqS EUGIJi7ox80eSnVlcmdlbiBHcm9zcyA8amdyb3NzQHN1c2UuZGU+wsB5BBMBAgAjBQJTjHDrA= hsD BwsJCAcDAgEGFQgCCQoLBBYCAwECHgECF4AACgkQsN6d1ii/Ey+LhQf9GL45eU5vOowA2u5N3= g3O ZUEBmDHVVbqMtzwlmNC4k9Kx39r5s2vcFl4tXqW7g9/ViXYuiDXb0RfUpZiIUW89siKrkzmQ5= dM7 wRqzgJpJwK8Bn2MIxAKArekWpiCKvBOB/Cc+3EXE78XdlxLyOi/NrmSGRIov0karw2RzMNOu5= D+j LRZQd1Sv27AR+IP3I8U4aqnhLpwhK7MEy9oCILlgZ1QZe49kpcumcZKORmzBTNh30FVKK1Evm= V2x AKDoaEOgQB4iFQLhJCdP1I5aSgM5IVFdn7v5YgEYuJYx37IoN1EblHI//x/e2AaIHpzK5h88N= Eaw QsaNRpNSrcfbFmAg987ATQRTjHAWAQgAyzH6AOODMBjgfWE9VeCgsrwH3exNAU32gLq2xvjpW= nHI s98ndPUDpnoxWQugJ6MpMncr0xSwFmHEgnSEjK/PAjppgmyc57BwKII3sV4on+gDVFJR6Y8ZR= wgn BC5mVM6JjQ5xDk8WRXljExRfUX9pNhdE5eBOZJrDRoLUmmjDtKzWaDhIg/+1Hzz93X4fCQkNV= bVF LELU9bMaLPBG/x5q4iYZ2k2ex6d47YE1ZFdMm6YBYMOljGkZKwYde5ldM9mo45mmwe0icXKLk= pEd IXKTZeKDO+Hdv1aqFuAcccTg9RXDQjmwhC3yEmrmcfl0+rPghO0Iv3OOImwTEe4co3c1mwARA= QAB wsBfBBgBAgAJBQJTjHAWAhsMAAoJELDendYovxMvQ/gH/1ha96vm4P/L+bQpJwrZ/dneZcmEw= Tbe 8YFsw2V/Buv6Z4Mysln3nQK5ZadD534CF7TDVft7fC4tU4PONxF5D+/tvgkPfDAfF77zy2AH1= vJz Q1fOU8lYFpZXTXIHb+559UqvIB8AdgR3SAJGHHt4RKA0F7f5ipYBBrC6cyXJyyoprT10EMvU8= VGi wXvTyJz3fjoYsdFzpWPlJEBRMedCot60g5dmbdrZ5DWClAr0yau47zpWj3enf1tLWaqcsuylW= svi uGjKGw7KHQd3bxALOknAp4dN3QwBYCKuZ7AddY9yjynVaD5X7nF9nO5BjR/i1DG86lem3iBDX= zXs ZDn8R38=3D =3D2wuH -----END PGP PUBLIC KEY BLOCK----- --------------E8F0A1D174FD905D8CBDB0A1-- --wWa1WkU4HwNLL3kYQ6SaCgMectahfLiGa-- --iUmYVvk9AcNu7UpvuoAWd0MLEaieoAgsE Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- wsB5BAABCAAjFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAl/ItQYFAwAAAAAACgkQsN6d1ii/Ey9t Rwf6A9tzXdXiLLON5l2hr3kE9X4E0RDfbk0NKxQX+ejvDYS65qCz+lmW5yZZXv3iF0uK/OsrPFJk debW3HhdK8ungmbfqMkOA/fRs3b/R+JSF1i6ctDlPOUUS8ReqckY7dcR2+HtVLGcA2UJPhNFN8vY K0Rigyw0tQf812MdX9zCTHIiN3mI0uNTjeJpdhu+lqLlYY5OC3WvrbL4lLH9DYsXkNkxz5izjHKI C04nlqAcpa/vILBKqSpgGduQ42uNNEwffefH4cVjWYqTJNzNw2hizkGkCYOEhQ8Ijxqzcvfju96A nGrWfFbL1d9ircGrTQzbkgnwh5ME2xxS6mQWcbwmXg== =MuND -----END PGP SIGNATURE----- --iUmYVvk9AcNu7UpvuoAWd0MLEaieoAgsE--