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Rao" To: CC: , , , , , , , "Nikhil P. Rao" Subject: [PATCH net] pds_core: order completion reads after the ownership check Date: Tue, 14 Jul 2026 20:41:45 +0000 Message-ID: <20260714204145.1782390-1-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: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF0000009C:EE_|MW4PR12MB6828:EE_ X-MS-Office365-Filtering-Correlation-Id: 0d357e3c-6240-4f3f-bb06-08dee1e85ad1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700016|376014|82310400026|23010399003|18002099003|56012099006|11063799006|13003099007; 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)(1800799024)(36860700016)(376014)(82310400026)(23010399003)(18002099003)(56012099006)(11063799006)(13003099007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: /Ztg9m45fLUt57xVi0aPRWqN8QR4Y7D16TwvKA1SYEVwfsHgWUT6a/3Jz/sgDpLiL58ClJ0oKfvvQhKYm5gLOL2AhUV7dXRrHGhVunQJxfD7TSBuyLUJU7cNDPqEMgi2BrENz/dZSMewQsz6QaBqUFRKYnteM9PVFyWxT8qZybDaqHjgZMFtcT3tY3NpD84yRaWwxuFLEpxLCrPFmAH60anWtO69YQYwRMXyc9LEkBPVADUDGTs5TFuV3mgXgfheg4ckPLFHgxCaRW+di52PUyF23kCBqYWD65jnGhlUJlZURJ069FWyilGA+qgCSZf23WZVAYOO/wCOHFJjwNmBx5gPrZtlc4febH31ABNlIXxPa577Xf/bgd+nYE/WBVF0W35b32VtFFMKuvTTZWG87RFOIHnUkPPm3VIVu7SOteU//qbLtYEhSsxYcKhqZINA X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Jul 2026 20:42:00.4990 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0d357e3c-6240-4f3f-bb06-08dee1e85ad1 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: CH2PEPF0000009C.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB6828 pdsc_process_adminq() and pdsc_process_notifyq() decide a completion is valid from its ownership field - the color bit for the adminq, the event id for the notifyq - then read the rest of the descriptor, with no barrier in between. On a weakly ordered architecture the CPU may read the payload first. Add dma_rmb() between the ownership read and the payload reads. 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/adminq.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/amd/pds_core/adminq.c b/drivers/net/ethernet/amd/pds_core/adminq.c index 097bb092bdb8..eadb4b604fbe 100644 --- a/drivers/net/ethernet/amd/pds_core/adminq.c +++ b/drivers/net/ethernet/amd/pds_core/adminq.c @@ -18,7 +18,13 @@ static int pdsc_process_notifyq(struct pdsc_qcq *qcq) comp = cq_info->comp; eid = le64_to_cpu(comp->event.eid); while (eid > pdsc->last_eid) { - u16 ecode = le16_to_cpu(comp->event.ecode); + u16 ecode; + + /* Order the payload read after the event id, the field the + * driver uses to detect a new completion. + */ + dma_rmb(); + ecode = le16_to_cpu(comp->event.ecode); switch (ecode) { case PDS_EVENT_LINK_CHANGE: @@ -101,6 +107,10 @@ void pdsc_process_adminq(struct pdsc_qcq *qcq) spin_lock_irqsave(&pdsc->adminq_lock, irqflags); comp = cq->info[cq->tail_idx].comp; while (pdsc_color_match(comp->color, cq->done_color)) { + /* Order the payload reads after the color bit, the field the + * driver uses to detect a new completion. + */ + dma_rmb(); q_info = &q->info[q->tail_idx]; q->tail_idx = (q->tail_idx + 1) & (q->num_descs - 1); -- 2.43.0