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McKenney" , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak References: <20260803124900.3328789-1-christian.gellermann@codasip.com> <20260803124900.3328789-3-christian.gellermann@codasip.com> <20260803133704.8802e73e1a212364e64f67ee@linux-foundation.org> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: <20260803133704.8802e73e1a212364e64f67ee@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: YQZPR01CA0136.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:87::7) To YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: YT2PR01MB9175:EE_|YT1PR01MB9497:EE_ X-MS-Office365-Filtering-Correlation-Id: 3b839be3-879f-4849-f8fd-08df02e002f8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|366016|1800799024|23010399003|6133799003|10067099003|4143699003|56012099006|18002099003|22082099003; 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Thus, invoking the barrier command will no >> longer be rejected by the kernel with EPERM. The test checking this will >> fail. Check if the memory barrier command has been registered and skip >> the test in this case. >> > > Who the heck maintains sched/membarrier? > > Short answer: everybody I've ever met. All are cheerfully cc'ed. > > Perhaps finer-tuned answer: Peter. Adding Michael in CC so he can have a look as well. Thanks, Mathieu > >> --- a/tools/testing/selftests/membarrier/membarrier_test_impl.h >> +++ b/tools/testing/selftests/membarrier/membarrier_test_impl.h >> @@ -113,6 +113,16 @@ static int test_membarrier_private_expedited_fail(void) >> int cmd = MEMBARRIER_CMD_PRIVATE_EXPEDITED, flags = 0; >> const char *test_name = "sys membarrier MEMBARRIER_CMD_PRIVATE_EXPEDITED not registered failure"; >> >> + /* >> + * Some C libraries, like Musl, register the private expedited barrier >> + * command when creating a thread. Expecting an EPERM on an unregistered >> + * command will therefore no longer work. Skip the test in this case. >> + */ >> + if (MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED & membarrier_get_registrations()) { >> + ksft_test_result_skip("%s test: Command already registered\n", test_name); >> + return 0; >> + } > > AI review > (https://sashiko.dev/#/patchset/20260803124900.3328789-1-christian.gellermann@codasip.com) > thinks that membarrier_get_registrations() can return -1 on old > kernels, so we should check for that before testing for > MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED. > > Seems nonsensical to me - membarrier_get_registrations() doesn't do that. > > And policy (my policy, at least) is that selftests test the kernel > they're shipped with and anyone who tries to run them against any older > or newer kernel is all out of luck. > > > That being said, and stepping back a bit, is this test testing > something which we would test? If pass/fail depends upon deepest > details of the chosen libc flavour then perhaps the whole test was > ill-conceived. wdyt? > > -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com