From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=pass header.oldest-pass=0 smtp.remote-ip=40.107.208.58 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1793088109; b=iF1n2FRLavl4W676Bpwy3kKvUpY9anTOV982jiRTG6ttkPl+ItsME/SsQSTWyI0PE4ki p4j56tyJ9kF/vJ8ukDnAowPQIy+EZhFBJ8i5b0kLZj9MNqJgFklxYv/asRsIRWQp7tjJ3 55rvB3bLyP2LXk0IsagKiu/JotHVRNvrm6cBIj1g7sYQS/6lHwjzX6+HuoHmYdxB8d0Fw sYb32B8mF07D/0LpTevu90YJ3ROyCgve49k9pY4KV9ymMZrcMqrl3/XeHpiuqIY7r6gMf caL8sryoKwSEeb+4XUKKPRPUs4JhPK1kKykq3A/2bszbPxPrb6FwUC0G+27LJZ+I/yQ== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793088109; h=DMARC-Filter:DKIM-Signature:Received:Received: Content-Transfer-Encoding:Content-Type:Date:Message-Id:Cc:Subject: From:To:X-Mailer:References:In-Reply-To:X-ClientProxiedBy: MIME-Version:X-MS-PublicTrafficType:X-MS-TrafficTypeDiagnostic: X-MS-Office365-Filtering-Correlation-Id:X-MS-Exchange-SenderADCheck: X-MS-Exchange-AntiSpam-Relay:X-Microsoft-Antispam: X-Microsoft-Antispam-Message-Info:X-Forefront-Antispam-Report: X-MS-Exchange-AntiSpam-MessageData-ChunkCount: X-MS-Exchange-AntiSpam-MessageData-0: X-MS-Exchange-AntiSpam-MessageData-1:X-OriginatorOrg: X-MS-Exchange-CrossTenant-Network-Message-Id: X-MS-Exchange-CrossTenant-AuthSource:X-MS-Exchange-CrossTenant-AuthAs: X-MS-Exchange-CrossTenant-OriginalArrivalTime: X-MS-Exchange-CrossTenant-FromEntityHeader: X-MS-Exchange-CrossTenant-Id:X-MS-Exchange-CrossTenant-MailboxType: X-MS-Exchange-CrossTenant-UserPrincipalName: X-MS-Exchange-Transport-CrossTenantHeadersStamped; bh=y61Sbqy0fqJ7uPcPqzjvwLUWsxXIkkNfEEbjMBRS80s=; b=q/OedJBWwsvr7O8s5HwsohmBPLW1XHk5UgjwUfJVJuo+pKZZ+4Iw8ucJHrS/6Qizuf6W lhGgB6vAdHGaa3zUwFobItchZV8sCl6ccD6yI2og1wJCbWNGP3l3Llzpbf3NyeDfmS3Uw EKHSX6KmAfeP9b/HPFVIrPUFfPenzg3tqQrzbVEpT23BzinOhpMmuow+yWXZ/pgkFKEnZ Npt4uBtJ+FsIj+ui8wH+6SwjF6Kyhhj1ByKPKfnCFUL4Suy3WG7tykUPwic2gxM6vQbbP u/p3XbP5isbnk3DxzwJtkXbibQovrhl85uOZRPpgG/26C8NbEdKTfZgiOY+E07jJHYQ== ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=MYbvhtfl; arc=pass header.oldest-pass=0 smtp.remote-ip=40.107.208.58 Received: from PH0PR06CU001.outbound.protection.outlook.com (mail-westus3azon11011058.outbound.protection.outlook.com [40.107.208.58]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (secp384r1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A3EB6606A320; Tue, 27 Oct 2026 08:01:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A3EB6606A320 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=MYbvhtfl ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=iEfMxrUuAx5Coz1Gdhp3k1tICL4W8nLfZzM/LcAGw1ZomeVnr3GfjmVVWtVmH4W1NaQD0DjMuf63Ou5HpqYiqhKfwkIZkga0mArq5Wb27YATiQZTCTYtSmZLjQUC8+aWjqW8bRMBVEPetjVURzOjqMHhDjBrG+tbf4nQ+BB3xMY8kXHqIPbeSRasgZiwJ3GX1bK/335A7C5YLq0chfgaA+ZqdnQD3mqs5mm3K050NKTuvZcCKpZHautipJAn5uvTimtl/ly7d4tqYxgi1alECyHlL50j8D3XrUZOD3TMp/XfgRRR2Ckjs1M/gNIv4rDVVEaPXjgggizmcXNRxaf64g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=y61Sbqy0fqJ7uPcPqzjvwLUWsxXIkkNfEEbjMBRS80s=; b=qyhTtD5Tzo8O1RHpPzBA5Cowp+GsIyuDmuSepWDfOGS4PZ6JD7FhpCuzNPyXEkXHXcZKoZJo6EFbqJp/oZtjZLN/oaV+gtj5NQ5hUJCzbXPOxKRvK1YqB46GA6jPBuIcaaUbZZinLy6wqnaiY/jX9V9viIB+qbSSHBPMbLdgvo0p9wUvSLTGhVagc6FeuOVtmy+KWY5eNlbznYJvo+4vPKjq9WhDEqfx9DtgM7cVFMnXXw3NLujT0W3IfAw4YEUFCuRv1v8DogdJGoII4BD72cGvbwrDddMyEYLw+dNl4OYQV3CAgbPQrH/HU+shLGq36NBivXmVcOO/rVm2dgYlUw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=y61Sbqy0fqJ7uPcPqzjvwLUWsxXIkkNfEEbjMBRS80s=; b=MYbvhtflKWtZ9eOq+karAeshCb4h23IQ/7y5TlKw11PCG13OC9U2iFjYUxoShJh2egLjmxTGOpwlyJyr0J06ra+OXOL3V6uCRKvqX7Q+r1uP8VpMb6/qhWRYFMHXBNujJhnay8wHcR9MKt5czwT7F7VbhoAVRkdWkBA0pGMeM9PqW8RzPeRy9pQMTzPGxoYSxqwesXtvg1BuSDR0ccaGhxjUtqRc6e20Y0LlGDXE1M4EuRDmU1ra1oj6uc/VcTZhtpP0ImsfZrA9AYZdozCR2mPE68vtUFL3fcw5piZADrMdKpAsB1JyrH3QykqiC/8F3WIZMMNASgCvfN8UKKGKhQ== Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from DS0PR12MB6413.namprd12.prod.outlook.com (2603:10b6:8:ce::10) by PH7PR12MB6659.namprd12.prod.outlook.com (2603:10b6:510:210::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.546.22; Tue, 27 Oct 2026 08:01:44 +0000 Received: from DS0PR12MB6413.namprd12.prod.outlook.com ([fe80::e82a:6673:4142:37fa]) by DS0PR12MB6413.namprd12.prod.outlook.com ([fe80::e82a:6673:4142:37fa%5]) with mapi id 15.21.0546.016; Tue, 27 Oct 2026 08:01:43 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 27 Oct 2026 17:01:40 +0900 Message-Id: Cc: "Alistair Popple" , "Timur Tabi" , "Eliot Courtney" , "Zhi Wang" , , , , , "dri-devel" Subject: Re: [PATCH v6 11/15] gpu: nova-core: gsp: cmdq: do not sleep when waiting for a message with timeout 0 From: "Eliot Courtney" To: "Alexandre Courbot" , "John Hubbard" , "Danilo Krummrich" , "Alice Ryhl" , "David Airlie" , "Simona Vetter" , "Benno Lossin" , "Gary Guo" X-Mailer: aerc 0.22.0-0-gc2f86b7abde3 References: <20261027-cmdq-rpc-v6-0-bed9669724ba@nvidia.com> <20261027-cmdq-rpc-v6-11-bed9669724ba@nvidia.com> In-Reply-To: <20261027-cmdq-rpc-v6-11-bed9669724ba@nvidia.com> X-ClientProxiedBy: TY4P286CA0065.JPNP286.PROD.OUTLOOK.COM (2603:1096:405:371::7) To DS0PR12MB6413.namprd12.prod.outlook.com (2603:10b6:8:ce::10) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB6413:EE_|PH7PR12MB6659:EE_ X-MS-Office365-Filtering-Correlation-Id: 6a9eeeea-03a1-49a7-b742-08df34008a56 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|10070799003|1800799024|23010399003|366016|22082099003|18002099003|261026121527099003|56012099006|11063799006|4143699003|10067099003|261021123027099003|261022105027099003|261026140227099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS0PR12MB6413.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(7416014)(10070799003)(1800799024)(23010399003)(366016)(22082099003)(18002099003)(261026121527099003)(56012099006)(11063799006)(4143699003)(10067099003)(261021123027099003)(261022105027099003)(261026140227099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 2 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?aUdsQzlkU2wwTUhrYUdraDFIMFFJZkV2YjN4SUN5RDJZQStpeEloYmp3T3FS?= =?utf-8?B?NzR2Szg0N3pvdjJaSzY0WEdKc1Mwb0RLZ2ZJa2pIcUdla1lGS1NQemhPU3BX?= =?utf-8?B?eG1QYThGZFAvUlpVNGpHcVdqQXlVYlFjUzJXSkdSUWFGVzlSYjFjdmdjNXBQ?= =?utf-8?B?L0VucFpjQjRiRU8ybXd4ZDBKa3Q3OW1SalZOWnpmbHBOakNlY1EwOERFdkJL?= =?utf-8?B?VHNyaWljU3cybTRZMFFCemdFd0dicGxaQVYzQ2lWdXZsK3dPanJzVDUzVUVa?= =?utf-8?B?T0UxOWJoYWR6NHd6aFljMmZPT09jRGhQNTlvRVNmQ2l5K0NyWDNhZlNyRHZ1?= =?utf-8?B?MFlZdXVFczkwYXE2UTRmNHdBNkZMRVAxQ3pwVzlMU0xwVUlrVXpFRkQwa3pT?= =?utf-8?B?dWpMN0oxa1BxbHF0V1lrOTB2Rmo1dm1wU2FBamk5cGdvTCszNTFUUWt6elVC?= =?utf-8?B?NDUvRHZzY280czZvS2tTejRkTytOZFRUU2NPYmovWTJxM01Rdy84SFQ4ZGlw?= =?utf-8?B?cEdFN040RHoxaUZnRmlEbDd4dTcxaW1XeWpNWG5vVk1hKy9JSGoyZE9BcWUv?= =?utf-8?B?dFhkcStTbkJTNmhJdWFZNjBGOWhFVjhTRFlKWG4wY25LbUx1THJCeGx3VlY4?= =?utf-8?B?WHZKdml3QUVmdDVTTHI1bHl1S1M2R2N6MFR1TzYrWlkwQ3lTYUZQcDNNZzN5?= =?utf-8?B?MkhsQThUcWNXK3hkeGpqaWRQQmM1cUxYZkRNSG9HOThuOVBkN1pxZjNGeWRO?= =?utf-8?B?KysxTkM1VkVvY3pMdjQ2UFRzak42QVpXK3VUZlVJK0NINFoyU3dQRDUzakxF?= =?utf-8?B?QlNmUFhrWmpGcml0OFlzM2hTUmJzMjdEM25ZUkF2Y1B1QUo0ZXBxMTRLRjkz?= =?utf-8?B?M3ZKaFVGMTZST2FOcFJZc09qODMyeDJCZU9jMEkwOC8wMkF2MTExZXJ3d0pO?= =?utf-8?B?TzZ2alU2dmhZcmxQUE55cmhZQzROSjVyQ0RmU3M0cGIwaXovdXZYWGZFUGwy?= =?utf-8?B?UFNzUHE5d0FVVkEwYWQ1dUNoeGg0SkZ4QWs0UXRBaURnWmdFNmpscGpEL1ZG?= =?utf-8?B?RFBWekh6YW4xWGVaRkxST0IraWI3NStLTGpQUGxwR09kTkEvM1dsay95K1lp?= =?utf-8?B?ZW9aNlFjZWEzZ3gySFhLbXMycGljY2xCa0RXL0tIcnltaDNIYnZXMkRDSkVm?= =?utf-8?B?SEZvN2hmNncwMjJJb3pFTU5vSVV4SWRJcEFDeWRIZERhakJ4TlZzYmJhdkFN?= =?utf-8?B?MDh0Q29VUnhvejkzVG96NmR4OFA5NDRtYzAvMllLeEx0ZFhwV2dxdStnWjNQ?= =?utf-8?B?cXpTSTBuRG45NzJ3Y2ozWFRuL2l3Z1NrRnRNQkd2MU1za0czc2lDMlVhMWdZ?= =?utf-8?B?RVZUYUgwY2h3ZGp4bUhKaGhaT1Nvcmg5VWs1RlFJS3Q5MFJwU3A4dHlubTRE?= =?utf-8?B?VW13Z2xlbnNDYVMxOEt6aDlXTVByb3BNOTl3UXJuVW5vTlRTNDlWeFhURHd5?= =?utf-8?B?OXlTUUZwMW5WdzZ6Ym5JTE0zSjIxbW4ralh5SUV6dW1oQTZXZFdleFRFYksr?= =?utf-8?B?N0NoQytlUXpVQ3hiZ00vc0lIUHVjU0U5Q1hKQXJPUXFENG5hNHhtM3FXMS9H?= =?utf-8?B?Slo5T2ViOW1GeUt4aHNpSkJLY3BMaDZIaElTa2pBaXlGclBXNjFIdGdVck81?= =?utf-8?B?YVU4cW5pRGEyOUtwQ0Y3VUVwaVJ1M2twSnRzRTRlWlByaFJoSlBON2MrT0R4?= =?utf-8?B?N0FHYUtjdWdZcTR1dnUzR2pJV3prbS9hc0huZXpkK0psTW5TRXNHUWR1TGdv?= =?utf-8?B?bzIraHl0bDFlNzZGa3B0NDUxeFh3Tkk4dk9JSHB0NkdlODNZQ2hUNmFrS1hD?= =?utf-8?B?MmFrL2UrazV5cXV4QnVPY0xKU3h5d0l0WGJiODRMaHo3Ynl5djNJd2dIcTZD?= =?utf-8?B?SlNDSTZ1a3dqSDJyNnovdUwwbzdhM01ndXJ4Qm9ZWEdzTk9nZzJ6dFhCeUQ3?= =?utf-8?B?OEtobVZ6eCs3L01qZEk0MjBLQkZrVlNEdDVaTlVEWEVhU1VxU21RUDUwY3RU?= =?utf-8?B?N3FLK3hKOWg0azVWVytQemczcEM0bHpVc2wxSHkvNytORUVvZWNXbHovTGZt?= =?utf-8?B?OXlOQ2RzckdoZS9oa0I0QTQwaGFEcWk0TzFFWm5PWUpwRVJMQVljaTJDRDFT?= =?utf-8?B?RHdibnd0WXpGK0hlTnI0UmlKdW9zYkdZWjFHZFM2YVhDejAyZ0FEVnZGWnVr?= =?utf-8?B?eHNaOVhlTWs2OXBMaGdqTXFjY1p1NGlXY3RvaXVQQXR4SnlnTnl1eUd0VjRY?= =?utf-8?B?am0rUVZQOFZXc2c2Z281ZDgwVWNBNFVWaUFXa2JJMHRqamVuNkZzMnFva05o?= =?utf-8?Q?uVs+9P9Cnd6hEIrzS/F9TIloJR7PkesoOoMax1o18jF7N?= X-MS-Exchange-AntiSpam-MessageData-1: OVL5KP58HRi1Nw== X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6a9eeeea-03a1-49a7-b742-08df34008a56 X-MS-Exchange-CrossTenant-AuthSource: DS0PR12MB6413.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Oct 2026 08:01:43.6759 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 4DOPUk7wb0LKM8ArI+2Vf2PDqmpEPehXlJ9ZdG/r/uHf2ej7ygco+0Wh470XJr/WqXMV6bEwvKqkRRcIcyIKpg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB6659 On Tue Oct 27, 2026 at 4:35 PM JST, Alexandre Courbot wrote: > `read_poll_timeout` can potentially sleep for the specified > `sleep_delta` if `timeout_delta` is `Delta::ZERO` and the system clock > is coarse enough to not register a tick between the time the function > has been called and the time the loop test is done. `wait_for_msg` has a > short test condition and is particularly vulnerable to this condition. > > Add a dedicated branch when `timeout` is `Delta::ZERO` to perform the > test without calling `read_poll_timeout` and avoid potentially sleeping > for 1ms. > > Signed-off-by: Alexandre Courbot > --- Reviewed-by: Eliot Courtney