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spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none From: Dario Faggioli To: Jan Beulich CC: "julien@xen.org" , "wl@xen.org" , "iwj@xenproject.org" , "sstabellini@kernel.org" , "mengxu@cis.upenn.edu" , "xen-devel@lists.xenproject.org" , "andrew.cooper3@citrix.com" , "George.Dunlap@eu.citrix.com" Subject: Re: [PATCH v2 01/12] xen/trace: Don't over-read trace objects Thread-Topic: [PATCH v2 01/12] xen/trace: Don't over-read trace objects Thread-Index: AQHXrkSLbMGUvlBXkkK2FQ1vuFXyFauzSsKAgARBtICABLtYgA== Date: Thu, 30 Sep 2021 08:07:12 +0000 Message-ID: References: <20210920172529.24932-1-andrew.cooper3@citrix.com> <20210920172529.24932-2-andrew.cooper3@citrix.com> <8e3f7318-2fb4-0011-f582-268816ebb59c@suse.com> In-Reply-To: <8e3f7318-2fb4-0011-f582-268816ebb59c@suse.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: yes X-MS-TNEF-Correlator: user-agent: Evolution 3.42.0 (by Flathub.org) authentication-results: suse.com; 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micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-xGn5+hbfUoMJp9efajUb" MIME-Version: 1.0 X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: AM0PR04MB5826.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 87d9c2b1-4fcb-4723-d80a-08d983e94f09 X-MS-Exchange-CrossTenant-originalarrivaltime: 30 Sep 2021 08:07:12.5500 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: T9jii470oxAjM/ybhHjJi672gXTAjladPFOAV7r4Xs7M1cUDFsxQEJKxpC80IYm1YfmkQVLleKCAUdvEQyfgPg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM4PR0401MB2307 --=-xGn5+hbfUoMJp9efajUb Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2021-09-27 at 09:51 +0200, Jan Beulich wrote: > On 24.09.2021 16:51, Dario Faggioli wrote: > > On Mon, 2021-09-20 at 18:25 +0100, Andrew Cooper wrote: > >=20 > > > There is one buggy race record, TRC_RTDS_BUDGET_BURN.=C2=A0 As it mus= t > > > remain > > > __packed (as cur_budget is misaligned), change bool has_extratime > > > to > > > uint32_t > > > to compensate. > > >=20 > > Mmm... maybe my understanding of data alignment inside structs is a > > bit > > lacking, but what the actual issue here, and what would we need to > > do > > to fix it (where, by fix, I mean us being able to get rid of the > > `__packed`)? > >=20 > > If rearranging fields is not enough, we can think about making > > priority_level and has_extratime smaller, or even combining them in > > just one field and decode the information in xentrace. >=20 > I guess Andrew has tried to avoid re-arranging field order so that > the consumer side doesn't need to also change. >=20 Right, but is it really worth it, in this case? Aren't we (very very likely) in control, by having them here in the tree, of all the consumers? And is is this a stable ABI? Also, both xentrace_format and xenalyze are being modified in this series anyway... Maybe there's still something I'm missing, but if we've getting rid of those ugly bitfields and __packed attributes, it seems to me that doing it completely --i.e., including in this case-- is worth the small change in the tools. Regards --=20 Dario Faggioli, Ph.D http://about.me/dario.faggioli Virtualization Software Engineer SUSE Labs, SUSE https://www.suse.com/ ------------------------------------------------------------------- <> (Raistlin Majere) --=-xGn5+hbfUoMJp9efajUb Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEES5ssOj3Vhr0WPnOLFkJ4iaW4c+4FAmFVcC8ACgkQFkJ4iaW4 c+76cA/+JRV2UjRtn7u7diOwwzTvGcK2MueTlmEJ5eRUme77UK+fUORK8W70UGEf T1Nbb6/7Hvsb5SyzFjptqplwLIKw1feu09tGOwEWT8uObZKALXy/LjH2PWdVYmlN gmEOuX2snBohCEZpdzlUrEzsZ61I+hXgEyCD+dQjLUEe3rGdDjS3Bt54ZURWzoxA 4QQ2VDoZ219h7tP1ReIRnTMpTQ8qX+nY3vsTGWR/4jomrN2cAHPv+Geua3oXSmq3 W1QN6OgBbRXlLnKLbf0ElRegnUsWwfC3/xSP/B9dQOh5HtMK/qTw9DQJiPjy7Cxb TVroR5abq451hRAaOIgj1iUeO1VW1FPyDlTqSeLZ7GcBUnM2B/M0i+FTDEnmPx1M MjFmfkWajEonnGCWhy9YZ4DC/p+Rw/5Gmn61dZ78iL05Rlb7tbg4ZGlVXEXjVhGt KfbAM9P8Ms+MVKqqtT8LH9K1XZSLkJqv+InhHpeb8Xcj68K0A5bml2CpFEytZpzy buEbXNcRXrALJPJ1rtP45loMQKpv8O4avhsAiFbUW3uc7I+oWGIDBhTZ/1+cHyxV ToI83k5eoWye3TuWz2lgR4QhZ8cCFYpsRScUtvnJsD41Y4f8+CT8Kr5KRtVf4IBU ZN+hQfbCxm8dMfrFwq49qA/db86gj78pX27VRTTu/TKEa+bTZ0M= =8dMA -----END PGP SIGNATURE----- --=-xGn5+hbfUoMJp9efajUb--