diff options
Diffstat (limited to 'kernel/sched/ext_idle.c')
| -rw-r--r-- | kernel/sched/ext_idle.c | 52 |
1 files changed, 44 insertions, 8 deletions
diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index 001fb88a8481..edd6cdd9aadc 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -75,7 +75,7 @@ static int scx_cpu_node_if_enabled(int cpu) return cpu_to_node(cpu); } -bool scx_idle_test_and_clear_cpu(int cpu) +static bool scx_idle_test_and_clear_cpu(int cpu) { int node = scx_cpu_node_if_enabled(cpu); struct cpumask *idle_cpus = idle_cpumask(node)->cpu; @@ -198,7 +198,7 @@ pick_idle_cpu_from_online_nodes(const struct cpumask *cpus_allowed, int node, u6 /* * Find an idle CPU in the system, starting from @node. */ -s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, int node, u64 flags) +static s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, int node, u64 flags) { s32 cpu; @@ -794,6 +794,16 @@ static void reset_idle_masks(struct sched_ext_ops *ops) cpumask_and(idle_cpumask(node)->smt, cpu_online_mask, node_mask); } } +#else /* !CONFIG_SMP */ +static bool scx_idle_test_and_clear_cpu(int cpu) +{ + return -EBUSY; +} + +static s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, int node, u64 flags) +{ + return -EBUSY; +} #endif /* CONFIG_SMP */ void scx_idle_enable(struct sched_ext_ops *ops) @@ -860,8 +870,34 @@ static bool check_builtin_idle_enabled(void) return false; } -s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags, - const struct cpumask *allowed, u64 flags) +/* + * Determine whether @p is a migration-disabled task in the context of BPF + * code. + * + * We can't simply check whether @p->migration_disabled is set in a + * sched_ext callback, because migration is always disabled for the current + * task while running BPF code. + * + * The prolog (__bpf_prog_enter) and epilog (__bpf_prog_exit) respectively + * disable and re-enable migration. For this reason, the current task + * inside a sched_ext callback is always a migration-disabled task. + * + * Therefore, when @p->migration_disabled == 1, check whether @p is the + * current task or not: if it is, then migration was not disabled before + * entering the callback, otherwise migration was disabled. + * + * Returns true if @p is migration-disabled, false otherwise. + */ +static bool is_bpf_migration_disabled(const struct task_struct *p) +{ + if (p->migration_disabled == 1) + return p != current; + else + return p->migration_disabled; +} + +static s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags, + const struct cpumask *allowed, u64 flags) { struct rq *rq; struct rq_flags rf; @@ -903,7 +939,7 @@ s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags, * selection optimizations and simply check whether the previously * used CPU is idle and within the allowed cpumask. */ - if (p->nr_cpus_allowed == 1 || is_migration_disabled(p)) { + if (p->nr_cpus_allowed == 1 || is_bpf_migration_disabled(p)) { if (cpumask_test_cpu(prev_cpu, allowed ?: p->cpus_ptr) && scx_idle_test_and_clear_cpu(prev_cpu)) cpu = prev_cpu; @@ -1125,10 +1161,10 @@ __bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu) if (!check_builtin_idle_enabled()) return false; - if (kf_cpu_valid(cpu, NULL)) - return scx_idle_test_and_clear_cpu(cpu); - else + if (!kf_cpu_valid(cpu, NULL)) return false; + + return scx_idle_test_and_clear_cpu(cpu); } /** |