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Rao" To: CC: , , , , , , , "Nikhil P. Rao" Subject: [PATCH net] pds_core: yield the CPU while waiting for the adminq to drain Date: Tue, 14 Jul 2026 20:14:56 +0000 Message-ID: <20260714201456.1776153-1-nikhil.rao@amd.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN1PEPF0000F0E1:EE_|DS5PPF4ACC15C0E:EE_ X-MS-Office365-Filtering-Correlation-Id: 5123be54-2f63-4011-4dd4-08dee1e4af47 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|36860700016|23010399003|82310400026|11063799006|6133799003|56012099006|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(1800799024)(36860700016)(23010399003)(82310400026)(11063799006)(6133799003)(56012099006)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: fXVCZ2sybM6ifcI91rnaITdDdR2mUOdwDv50XRVSoUIrZfLmNGspKNILQDhIKGOd0iJXISefBw26BMAwxeT40ioYkbbaHuH7ojKmZG7PcfxTUpIuiF89jrUkCgrbsBrYz/fenZEuixEA/ZtTaoxqPtLsAJn/+g2p/dbSe/7yIlfpi23rJhnGhC2ntbrj0tHSxKiOAAZZfYwodvtSNhDIMV2ORCnNCax7Y8RpsZAI/XMj/A20aPu+papwm6KS2nNMAJITJ+QZPizFD54ZGaMt/k3nICLn3punLwXoEAr/QaNJZe6jbVsexf0H4zs/AWg+R0tNaDnhK4jKsS5o0Tz0mrSy0J0S0tAV6sgsVmQuyEgS+1oNTcdUaKzmAZ6MkPOgbKlYNwN3ndm0r9FXbhBtmuWzSZJzQdLqAO7qYR4Wvq1YTpsGn7M6EkrRy1Mu6D0K X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Jul 2026 20:15:44.2245 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5123be54-2f63-4011-4dd4-08dee1e4af47 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MN1PEPF0000F0E1.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS5PPF4ACC15C0E pdsc_adminq_wait_and_dec_once_unused() busy-waits for adminq_refcnt to drop to one: while (!refcount_dec_if_one(&pdsc->adminq_refcnt)) cpu_relax(); The refcount is held by pdsc_adminq_post() for the duration of an in-flight command, which can wait up to devcmd_timeout seconds (PDS_CORE_DEVCMD_TIMEOUT is 5) for the hardware to complete. cpu_relax() is not a reschedule point, so on a non-preemptible kernel this loop can spin on the CPU for several seconds, starving other tasks on that core. Add cond_resched() to the loop so the waiter yields to other runnable tasks while it polls, keeping cpu_relax() as the busy-wait hint between checks. Fixes: 7e82a8745b95 ("pds_core: Prevent race issues involving the adminq") Reported-by: sashiko-bot Closes: https://sashiko.dev/#/patchset/20260629200358.2626129-1-nikhil.rao%40amd.com?part=2 Signed-off-by: Nikhil P. Rao Reviewed-by: Eric Joyner --- drivers/net/ethernet/amd/pds_core/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/ethernet/amd/pds_core/core.c b/drivers/net/ethernet/amd/pds_core/core.c index 38a2446571af..19eeb5b06f4d 100644 --- a/drivers/net/ethernet/amd/pds_core/core.c +++ b/drivers/net/ethernet/amd/pds_core/core.c @@ -533,6 +533,7 @@ static void pdsc_adminq_wait_and_dec_once_unused(struct pdsc *pdsc) dev_dbg_ratelimited(pdsc->dev, "%s: adminq in use\n", __func__); cpu_relax(); + cond_resched(); } } -- 2.43.0