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Date: Mon, 22 Aug 2022 10:15:15 +0800 From: Pingfan Liu <kernelfans@...il.com> To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Cc: Pingfan Liu <kernelfans@...il.com>, Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com> Subject: [RFC 05/10] perf/arm-dsu: Make dsu_pmu_cpu_teardown() parallel In the case of kexec quick reboot, dsu_pmu_cpu_teardown() confronts parallel and lock are needed to protect the contest on a dsu_pmu. Signed-off-by: Pingfan Liu <kernelfans@...il.com> Cc: Will Deacon <will@...nel.org> Cc: Mark Rutland <mark.rutland@....com> To: linux-arm-kernel@...ts.infradead.org To: linux-kernel@...r.kernel.org --- drivers/perf/arm_dsu_pmu.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c index a36698a90d2f..aa9f4393ff0c 100644 --- a/drivers/perf/arm_dsu_pmu.c +++ b/drivers/perf/arm_dsu_pmu.c @@ -833,16 +833,23 @@ static int dsu_pmu_cpu_teardown(unsigned int cpu, struct hlist_node *node) struct dsu_pmu *dsu_pmu = hlist_entry_safe(node, struct dsu_pmu, cpuhp_node); - if (!cpumask_test_and_clear_cpu(cpu, &dsu_pmu->active_cpu)) + raw_spin_lock(&dsu_pmu->pmu_lock); + if (!cpumask_test_and_clear_cpu(cpu, &dsu_pmu->active_cpu)) { + raw_spin_unlock(&dsu_pmu->pmu_lock); return 0; + } dst = dsu_pmu_get_online_cpu_any_but(dsu_pmu, cpu); /* If there are no active CPUs in the DSU, leave IRQ disabled */ - if (dst >= nr_cpu_ids) + if (dst >= nr_cpu_ids) { + raw_spin_unlock(&dsu_pmu->pmu_lock); return 0; + } - perf_pmu_migrate_context(&dsu_pmu->pmu, cpu, dst); + /* dst should not be in dying mask. So after setting, blocking parallel */ dsu_pmu_set_active_cpu(dst, dsu_pmu); + raw_spin_unlock(&dsu_pmu->pmu_lock); + perf_pmu_migrate_context(&dsu_pmu->pmu, cpu, dst); return 0; } @@ -858,6 +865,7 @@ static int __init dsu_pmu_init(void) if (ret < 0) return ret; dsu_pmu_cpuhp_state = ret; + cpuhp_set_step_parallel(ret); return platform_driver_register(&dsu_pmu_driver); } -- 2.31.1
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