From a048ca5f00ebd5a44f8551d546a3cd81fed7a204 Mon Sep 17 00:00:00 2001 From: Gabriele Monaco Date: Thu, 20 Nov 2025 15:56:48 +0100 Subject: [PATCH] timers/migration: Add mask for CPUs available in the hierarchy Keep track of the CPUs available for timer migration in a cpumask. This prepares the ground to generalise the concept of unavailable CPUs. Signed-off-by: Gabriele Monaco Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Reviewed-by: Thomas Gleixner Link: https://patch.msgid.link/20251120145653.296659-3-gmonaco@redhat.com --- kernel/time/timer_migration.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c index 2cfebed35e225..3325ca7989b3c 100644 --- a/kernel/time/timer_migration.c +++ b/kernel/time/timer_migration.c @@ -424,6 +424,12 @@ static struct tmigr_group *tmigr_root; static DEFINE_PER_CPU(struct tmigr_cpu, tmigr_cpu); +/* + * CPUs available for timer migration. + * Protected by cpuset_mutex (with cpus_read_lock held) or cpus_write_lock. + */ +static cpumask_var_t tmigr_available_cpumask; + #define TMIGR_NONE 0xFF #define BIT_CNT 8 @@ -1433,6 +1439,7 @@ static int tmigr_clear_cpu_available(unsigned int cpu) int migrator; u64 firstexp; + cpumask_clear_cpu(cpu, tmigr_available_cpumask); raw_spin_lock_irq(&tmc->lock); tmc->available = false; WRITE_ONCE(tmc->wakeup, KTIME_MAX); @@ -1446,7 +1453,7 @@ static int tmigr_clear_cpu_available(unsigned int cpu) raw_spin_unlock_irq(&tmc->lock); if (firstexp != KTIME_MAX) { - migrator = cpumask_any_but(cpu_online_mask, cpu); + migrator = cpumask_any(tmigr_available_cpumask); work_on_cpu(migrator, tmigr_trigger_active, NULL); } @@ -1461,6 +1468,7 @@ static int tmigr_set_cpu_available(unsigned int cpu) if (WARN_ON_ONCE(!tmc->tmgroup)) return -EINVAL; + cpumask_set_cpu(cpu, tmigr_available_cpumask); raw_spin_lock_irq(&tmc->lock); trace_tmigr_cpu_available(tmc); tmc->idle = timer_base_is_idle(); @@ -1805,6 +1813,11 @@ static int __init tmigr_init(void) if (ncpus == 1) return 0; + if (!zalloc_cpumask_var(&tmigr_available_cpumask, GFP_KERNEL)) { + ret = -ENOMEM; + goto err; + } + /* * Calculate the required hierarchy levels. Unfortunately there is no * reliable information available, unless all possible CPUs have been -- 2.47.3