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Date: Thu, 22 Jan 2026 12:30:35 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper Subject: Re: [PATCH v4 6/8] x86/HPET: simplify "expire" check a little in reprogram_hpet_evt_channel() Message-ID: References: <57f34114-54b7-483d-8ac0-e9fa49df959f@suse.com> <0bc920e2-2e32-4b3d-9ed0-a2c2b34e9591@suse.com> <73daede9-d7ac-44bf-a018-b76d39b3eeb4@suse.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <73daede9-d7ac-44bf-a018-b76d39b3eeb4@suse.com> X-ClientProxiedBy: PA7P264CA0528.FRAP264.PROD.OUTLOOK.COM (2603:10a6:102:3db::13) To CH7PR03MB7860.namprd03.prod.outlook.com (2603:10b6:610:24e::14) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH7PR03MB7860:EE_|DSWPR03MB989131:EE_ X-MS-Office365-Filtering-Correlation-Id: 873eb92b-073e-4965-fbe0-08de59a9ab7d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|376014|7053199007; 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> >> return -ETIME; > >> } > >> > >> if ( unlikely(expire == 0) ) > >> { > >> ASSERT_UNREACHABLE(); > >> return -ETIME; > >> } > >> > >> which I fear I don't like (for going too far). Even > >> > >> if ( unlikely(expire <= 0) ) > >> { > >> printk(KERN_DEBUG "reprogram: expire <= 0\n"); > >> ASSERT(expire); > >> return -ETIME; > >> } > >> > >> I'd be uncertain about, as that needlessly gives 0 a meaning that isn't > >> required anymore in this function. > > > > Hm, OK, I was under the impression that both < 0 and 0 should never be > > passed by the callers. If expire == 0 is a possible input then I > > don't think the ASSERT() is that helpful. > > Oh, so you were after > > if ( unlikely(expire <= 0) ) > { > printk(KERN_DEBUG "reprogram: expire <= 0\n"); > ASSERT_UNREACHABLE(); > return -ETIME; > } > > (perhaps even with the printk() dropped)? That I could buy off on, as NOW() > is expected to only ever return valid (positive) s_time_t values. Yes, that's what I was thinking off, but your previous reply made me think there are possible cases where expire < 0 gets passed to the function? If that's not the case, adding the ASSERT_UNREACHABLE() would be my preference. Thanks, Roger.