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Fri, 11 Jul 2025 15:04:37 -0700 Date: Fri, 11 Jul 2025 15:04:36 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: Xu Yilun , , , , , , , , , , , , Subject: Re: [PATCH v4 2/7] iommufd: Add iommufd_object_tombstone_user() helper Message-ID: References: <20250709040234.1773573-1-yilun.xu@linux.intel.com> <20250709040234.1773573-3-yilun.xu@linux.intel.com> <20250711213323.GH1951027@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250711213323.GH1951027@nvidia.com> X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PEPF000023D9:EE_|SN7PR12MB7979:EE_ X-MS-Office365-Filtering-Correlation-Id: b251c8c8-c309-4165-056e-08ddc0c6f2f0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|36860700013|1800799024|376014|7416014; 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jul 2025 22:04:46.7907 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b251c8c8-c309-4165-056e-08ddc0c6f2f0 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF000023D9.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7979 On Fri, Jul 11, 2025 at 06:33:23PM -0300, Jason Gunthorpe wrote: > On Fri, Jul 11, 2025 at 11:02:53PM +0800, Xu Yilun wrote: > > > let's write something like this (correcting typos too): > > > > > > /* > > > * We can't use xa_empty(), as a tombstone (NULLed entry) would > > ^ > > > * prevent it returning true, unlike xa_for_each() ignoring the > > > * NULLed entries. So use an empty flag instead of xa_empty() to > > ^ > > s/NULLed/zeroed, are they? > > Maybe: > > We can't use xa_empty() to end the loop as the tombstones are stored > as XA_ZERO_ENTRY in the xarray. However xa_for_each() automatically > converts them to NULL and skips them causing xa_empty() to be kept > false. Thus once xa_for_each() finds no further !NULL entries the > loop is done. > > ? +1