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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: UMnSdlffD7npf1vBRhzb9MbjWLTVzIW9bDuQ8/D3ecIFBdXkXBJX6NXGDMoxcSKRbAgHMXq8Ho4YyODRooeJqhBBUDEKP3QY4+pftPnBfSMqvAyf0wkL3g+cJ90MPwKuhwdstzVurzzoF2wj9rhtCpendXBLu0ano9WMt4vegKVyKxK8B+KDBDoucBvrIc6+QvJ1rxM2OqSzyXWHF59qs+uvRe5yH1JFnMrPY4eJm7OTNniTUamH6vBoraeUOCOXK6ZIjcoEluC/xdBt/DM2NIvJVbJMbg0cHMD+gmsLZOZ5KcsLceuBnyRw6M+YfrnBboEjIEszP+X6PIUd1sKAGONHRLmAsiDYyx+uWnnJd6nXkZUw3KrVXy6e46teq8d3WltYhFUAtx7CsFwUfMKnwa6KfsYcqWFyBluRSm9YQttSvhlBNhKunMaJQpIcaya1 X-OriginatorOrg: xsightlabs.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Apr 2026 14:28:28.8394 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 2039b827-d05d-4467-0757-08dea469403a X-MS-Exchange-CrossTenant-Id: 646a3e34-83ea-4273-9177-ab01923abaa9 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=646a3e34-83ea-4273-9177-ab01923abaa9;Ip=[52.17.62.50];Helo=[eu-dlp.cloud-sec-av.com] X-MS-Exchange-CrossTenant-AuthSource: AM3PEPF00009BA1.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM0P193MB3171 On 4/21/2026 6:05 AM, Sudeep Holla wrote: > On Fri, Apr 17, 2026 at 11:14:29AM +0800, Huisong Li wrote: >> In some scenarios, PCC command may experience probabilistic timeout. >> This is primarily caused by the chan_in_use flag being updated after >> ringing the doorbell, coupled with a lack of proper memory barriers >> across CPU cores. >> >> On fast platforms, a race condition occurs: the platform processing >> completes and triggers an interrupt before the local CPU sets >> chan_in_use to true. When the interrupt handler pcc_mbox_irq() runs, >> it reads chan_in_use as false and incorrectly ignores the interrupt. >> >> This patch fixes the race by: >> 1. Moving the chan_in_use update before ringing the doorbell. >> 2. Using smp_store_release() to ensure the flag update is visible >> to other cores before subsequent hardware or software actions >> are triggered. >> 3. Using smp_load_acquire() in the interrupt handler to ensure the >> latest flag value is read before deciding to skip the interrupt. >> > > Are you seeing the issue on real platforms or you are just reviewing the > code. I would like to test it on the platform I use but I don't have it > handy, so may take some time. > > I have added Robbie King who also has helped in testing this PCC driver > in the past. > I was unable to apply the patch to our current kernel version. We are in the process of updating our kernel modules to support 7.0, once that effort is finished I can run a few of our current regressions against the patch.