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=?utf-8?B?YzE2ajZHYk8zQTE5VllLcGIzcHZqcDAwTjVsNUZFUU9yZ25TVE5sOEFlNUUv?= =?utf-8?B?QWo4Y0xLdy9WVTdkNkJIM1dkRVlxNGo2Sm9ZK0hrUWVONEcza1I0Z2xnRmVU?= =?utf-8?B?ZWNBV2syNHpKQll3OHVXSEZqKzJCZUdSQ1lWeUVKcEVXYjllelRZWUZQZHA1?= =?utf-8?B?QlZpZ0dNMHdLUFZuUnlxWUQ0NkRLSjNZaUswZHpTaFplQmRnWVMxakplbWhL?= =?utf-8?B?SGNNWEM4SmpXUkVxY1BUZDBpak5JZkxRdDgzTHRXWU9pQy9BUy9yTGZhWk5v?= =?utf-8?Q?gBl3eoDMpXrZtniQ=3D?= X-OriginatorOrg: efficios.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5b66b566-ba05-452a-ce3d-08df27d32108 X-MS-Exchange-CrossTenant-AuthSource: YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Oct 2026 20:06:25.6418 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4f278736-4ab6-415c-957e-1f55336bd31e X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 3w1UvAKyuuTKvJarG/0Ehq9pJEyPPGt94e5C11zH+8O/ZpDRrmG8c1FsFTKsh8sVBjp5inZghQC3Xj71/qg+mcEexwuptmzMAGglnYNujwo= X-MS-Exchange-Transport-CrossTenantHeadersStamped: YT8PR01MB612386 On 2026-10-11 15:59, Bradley Morgan wrote: > On 11 October 2026 20:48:50 BST, Mathieu Desnoyers > wrote: >> Introduce a "try acquire" hazard pointer fast path, which performs an >> early load of the address to store it into the hazard pointer slot, and >> then re-loads that address after a barrier to check whether it has >> changed meanwhile. >> >> On comparison failure, rather than re-try, guarantee forward progress by >> falling back to the __hazptr_acquire slow path on failure. >> >> The acquire slow path attempts a try-acquire for any available per-CPU >> slot. If that fails, it chains the backup slot into the overflow list, >> therefore guaranteeing forward progress for both hazard pointer >> read-side and synchronize: >> >> - Readers set the wildcard, and then proceed to set the more >> specific address to replace the wildcard. >> >> - One synchronize alternates between two overflow list periods, >> scanning each one while readers are added to the other period, >> thus preventing a steady flow of readers from preventing >> synchronize forward progress. >> >> With this change, the scan on per-CPU slots don't need to expect a >> wildcard anymore, because none can be produced by readers. Wildcards are >> only expected within overflow lists. >> >> Signed-off-by: Mathieu Desnoyers >> Suggested-by: Gary Guo >> Link: https://lore.kernel.org/lkmm/DLK9MW1N86KD.2GRWUAD2NX4FU@garyguo.net/ >> Reviewed-by: Gary Guo > > Hi, my R-B still stands from > > https://lore.kernel.org/all/C53DEBF5-555F-44A8-A11C-A15C83AAD341@mainlining.org/ > > Reviewed-by: Bradley Morgan Sorry, I forgot to add it to my commit message. I'll add it to the next round (if there is one), else hopefully Paul can add the R-B tag if he picks up this series. Thanks! Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com