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However, struct rq's rd field was missing the __rcu compiler annotation, and several lockless readers across the scheduler subsystem accessed rq->rd directly without using RCU dereference primitives. Add the __rcu annotation to struct rq's rd field. For code clarity, introduce the rcu_dereference_root_domain() helper macro to validate access under sched_domains_mutex or active RCU-sched read-side critical sections. While mechanically identical to rcu_dereference_sched_domain(), defining rcu_dereference_root_domain() preserves the natural symmetry of rq->rd and rq->sd in struct rq, while keeping grep-ability straightforward. Update readers and accessors across kernel/sched/ to use rcu_dereference_root_domain(). This ensures proper memory ordering, enables Sparse static analysis validation, and avoids false Lockdep warnings under CONFIG_PROVE_RCU. Signed-off-by: Aaron Tomlin --- kernel/sched/core.c | 24 ++++++++----- kernel/sched/deadline.c | 77 ++++++++++++++++++++++------------------- kernel/sched/fair.c | 27 +++++++++------ kernel/sched/rt.c | 64 +++++++++++++++++++--------------- kernel/sched/sched.h | 7 ++-- kernel/sched/syscalls.c | 8 ++--- kernel/sched/topology.c | 13 +++---- 7 files changed, 127 insertions(+), 93 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d7c3b43158de..4ead07fd0f6d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8542,8 +8542,10 @@ void set_rq_online(struct rq *rq) { if (!rq->online) { const struct sched_class *class; + struct root_domain *rd; - cpumask_set_cpu(rq->cpu, rq->rd->online); + rd = rcu_dereference_root_domain(rq->rd); + cpumask_set_cpu(rq->cpu, rd->online); rq->online = 1; for_each_class(class) { @@ -8557,6 +8559,7 @@ void set_rq_offline(struct rq *rq) { if (rq->online) { const struct sched_class *class; + struct root_domain *rd; update_rq_clock(rq); for_each_class(class) { @@ -8564,7 +8567,8 @@ void set_rq_offline(struct rq *rq) class->rq_offline(rq); } - cpumask_clear_cpu(rq->cpu, rq->rd->online); + rd = rcu_dereference_root_domain(rq->rd); + cpumask_clear_cpu(rq->cpu, rd->online); rq->online = 0; } } @@ -8572,10 +8576,12 @@ void set_rq_offline(struct rq *rq) static inline void sched_set_rq_online(struct rq *rq, int cpu) { struct rq_flags rf; + struct root_domain *rd; rq_lock_irqsave(rq, &rf); - if (rq->rd) { - BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); + rd = rcu_dereference_root_domain(rq->rd); + if (rd) { + BUG_ON(!cpumask_test_cpu(cpu, rd->span)); set_rq_online(rq); } rq_unlock_irqrestore(rq, &rf); @@ -8584,10 +8590,12 @@ static inline void sched_set_rq_online(struct rq *rq, int cpu) static inline void sched_set_rq_offline(struct rq *rq, int cpu) { struct rq_flags rf; + struct root_domain *rd; rq_lock_irqsave(rq, &rf); - if (rq->rd) { - BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); + rd = rcu_dereference_root_domain(rq->rd); + if (rd) { + BUG_ON(!cpumask_test_cpu(cpu, rd->span)); set_rq_offline(rq); } rq_unlock_irqrestore(rq, &rf); @@ -9009,8 +9017,8 @@ void __init sched_init(void) #endif rq->next_class = &idle_sched_class; - rq->sd = NULL; - rq->rd = NULL; + RCU_INIT_POINTER(rq->sd, NULL); + RCU_INIT_POINTER(rq->rd, NULL); rq->cpu_capacity = SCHED_CAPACITY_SCALE; rq->balance_callback = &balance_push_callback; rq->active_balance = 0; diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index c0ebdcde5fe5..2dcb3722c317 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -122,12 +122,12 @@ static inline struct dl_bw *dl_bw_of(int i) { RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), "sched RCU must be held"); - return &cpu_rq(i)->rd->dl_bw; + return &rcu_dereference_root_domain(cpu_rq(i)->rd)->dl_bw; } static inline int dl_bw_cpus(int i) { - struct root_domain *rd = cpu_rq(i)->rd; + struct root_domain *rd = rcu_dereference_root_domain(cpu_rq(i)->rd); RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), "sched RCU must be held"); @@ -156,16 +156,13 @@ static inline unsigned long dl_bw_capacity(int i) arch_scale_cpu_capacity(i) == SCHED_CAPACITY_SCALE) { return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT; } else { - RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), - "sched RCU must be held"); - - return __dl_bw_capacity(cpu_rq(i)->rd->span); + return __dl_bw_capacity(rcu_dereference_root_domain(cpu_rq(i)->rd)->span); } } bool dl_bw_visited(int cpu, u64 cookie) { - struct root_domain *rd = cpu_rq(cpu)->rd; + struct root_domain *rd = rcu_dereference_root_domain(cpu_rq(cpu)->rd); if (rd->visit_cookie == cookie) return true; @@ -533,15 +530,18 @@ void init_dl_rq(struct dl_rq *dl_rq) static inline int dl_overloaded(struct rq *rq) { - return atomic_read(&rq->rd->dlo_count); + return atomic_read(&rcu_dereference_root_domain(rq->rd)->dlo_count); } static inline void dl_set_overload(struct rq *rq) { + struct root_domain *rd; + if (!rq->online) return; - cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask); + rd = rcu_dereference_root_domain(rq->rd); + cpumask_set_cpu(rq->cpu, rd->dlo_mask); /* * Must be visible before the overload count is * set (as in sched_rt.c). @@ -549,16 +549,19 @@ static inline void dl_set_overload(struct rq *rq) * Matched by the barrier in pull_dl_task(). */ smp_wmb(); - atomic_inc(&rq->rd->dlo_count); + atomic_inc(&rd->dlo_count); } static inline void dl_clear_overload(struct rq *rq) { + struct root_domain *rd; + if (!rq->online) return; - atomic_dec(&rq->rd->dlo_count); - cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask); + rd = rcu_dereference_root_domain(rq->rd); + atomic_dec(&rd->dlo_count); + cpumask_clear_cpu(rq->cpu, rd->dlo_mask); } #define __node_2_pdl(node) \ @@ -699,14 +702,15 @@ static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p * since p is still hanging out in the old (now moved to default) root * domain. */ - dl_b = &rq->rd->dl_bw; + dl_b = &rcu_dereference_root_domain(rq->rd)->dl_bw; raw_spin_lock(&dl_b->lock); - __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span)); + __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rcu_dereference_root_domain(rq->rd)->span)); raw_spin_unlock(&dl_b->lock); - dl_b = &later_rq->rd->dl_bw; + dl_b = &rcu_dereference_root_domain(later_rq->rd)->dl_bw; raw_spin_lock(&dl_b->lock); - __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(later_rq->rd->span)); + __dl_add(dl_b, p->dl.dl_bw, + cpumask_weight(rcu_dereference_root_domain(later_rq->rd)->span)); raw_spin_unlock(&dl_b->lock); set_task_cpu(p, later_rq->cpu); @@ -2222,9 +2226,10 @@ static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) if (dl_rq->earliest_dl.curr == 0 || dl_time_before(deadline, dl_rq->earliest_dl.curr)) { if (dl_rq->earliest_dl.curr == 0) - cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER); + cpupri_set(&rcu_dereference_root_domain(rq->rd)->cpupri, rq->cpu, + CPUPRI_HIGHER); dl_rq->earliest_dl.curr = deadline; - cpudl_set(&rq->rd->cpudl, rq->cpu, deadline); + cpudl_set(&rcu_dereference_root_domain(rq->rd)->cpudl, rq->cpu, deadline); } } @@ -2239,14 +2244,15 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) if (!dl_rq->dl_nr_running) { dl_rq->earliest_dl.curr = 0; dl_rq->earliest_dl.next = 0; - cpudl_clear(&rq->rd->cpudl, rq->cpu, rq->online); - cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr); + cpudl_clear(&rcu_dereference_root_domain(rq->rd)->cpudl, rq->cpu, rq->online); + cpupri_set(&rcu_dereference_root_domain(rq->rd)->cpupri, rq->cpu, + rq->rt.highest_prio.curr); } else { struct rb_node *leftmost = rb_first_cached(&dl_rq->root); struct sched_dl_entity *entry = __node_2_dle(leftmost); dl_rq->earliest_dl.curr = entry->deadline; - cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline); + cpudl_set(&rcu_dereference_root_domain(rq->rd)->cpudl, rq->cpu, entry->deadline); } } @@ -2686,12 +2692,14 @@ static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) { + struct root_domain *rd = rcu_dereference_root_domain(rq->rd); + /* * Current can't be migrated, useless to reschedule, * let's hope p can move out. */ if (rq->curr->nr_cpus_allowed == 1 || - !cpudl_find(&rq->rd->cpudl, rq->donor, NULL)) + !cpudl_find(&rd->cpudl, rq->donor, NULL)) return; /* @@ -2699,7 +2707,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) * see if it is pushed or pulled somewhere else. */ if (p->nr_cpus_allowed != 1 && - cpudl_find(&rq->rd->cpudl, p, NULL)) + cpudl_find(&rd->cpudl, p, NULL)) return; resched_curr(rq); @@ -2951,7 +2959,7 @@ static int find_later_rq(struct task_struct *task) * We have to consider system topology and task affinity * first, then we can look for a suitable CPU. */ - if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask)) + if (!cpudl_find(&rcu_dereference_root_domain(task_rq(task)->rd)->cpudl, task, later_mask)) return -1; /* @@ -3235,7 +3243,7 @@ static void pull_dl_task(struct rq *this_rq) */ smp_rmb(); - for_each_cpu(cpu, this_rq->rd->dlo_mask) { + for_each_cpu(cpu, rcu_dereference_root_domain(this_rq->rd)->dlo_mask) { if (this_cpu == cpu) continue; @@ -3358,10 +3366,8 @@ static void set_cpus_allowed_dl(struct task_struct *p, bool dl_task_needs_bw_move(struct task_struct *p, const struct cpumask *new_mask) { - if (!dl_task(p)) - return false; - - return !cpumask_intersects(task_rq(p)->rd->span, new_mask); + guard(rcu)(); + return !cpumask_intersects(rcu_dereference_root_domain(task_rq(p)->rd)->span, new_mask); } /* Assumes rq->lock is held */ @@ -3371,9 +3377,10 @@ static void rq_online_dl(struct rq *rq) dl_set_overload(rq); if (rq->dl.dl_nr_running > 0) - cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr); + cpudl_set(&rcu_dereference_root_domain(rq->rd)->cpudl, rq->cpu, + rq->dl.earliest_dl.curr); else - cpudl_clear(&rq->rd->cpudl, rq->cpu, true); + cpudl_clear(&rcu_dereference_root_domain(rq->rd)->cpudl, rq->cpu, true); } /* Assumes rq->lock is held */ @@ -3382,7 +3389,7 @@ static void rq_offline_dl(struct rq *rq) if (rq->dl.overloaded) dl_clear_overload(rq); - cpudl_clear(&rq->rd->cpudl, rq->cpu, false); + cpudl_clear(&rcu_dereference_root_domain(rq->rd)->cpudl, rq->cpu, false); } void __init init_sched_dl_class(void) @@ -3443,10 +3450,10 @@ void dl_add_task_root_domain(struct task_struct *p) cpu = cpumask_first_and(cpu_active_mask, msk); BUG_ON(cpu >= nr_cpu_ids); rq = cpu_rq(cpu); - dl_b = &rq->rd->dl_bw; + dl_b = &rcu_dereference_root_domain(rq->rd)->dl_bw; raw_spin_lock(&dl_b->lock); - __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span)); + __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rcu_dereference_root_domain(rq->rd)->span)); raw_spin_unlock(&dl_b->lock); raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); } @@ -3507,7 +3514,7 @@ void dl_clear_root_domain(struct root_domain *rd) void dl_clear_root_domain_cpu(int cpu) { - dl_clear_root_domain(cpu_rq(cpu)->rd); + dl_clear_root_domain(rcu_dereference_root_domain(cpu_rq(cpu)->rd)); } static void switched_from_dl(struct rq *rq, struct task_struct *p) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0feec172fd37..201864ef8c61 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8043,13 +8043,14 @@ static inline void set_rd_overutilized(struct root_domain *rd, bool flag) static inline void check_update_overutilized_status(struct rq *rq) { + struct root_domain *rd = rcu_dereference_root_domain(rq->rd); + /* * overutilized field is used for load balancing decisions only * if energy aware scheduler is being used */ - - if (!is_rd_overutilized(rq->rd) && cpu_overutilized(rq->cpu)) - set_rd_overutilized(rq->rd, 1); + if (rd && !is_rd_overutilized(rd) && cpu_overutilized(rq->cpu)) + set_rd_overutilized(rd, 1); } /* Runqueue only has SCHED_IDLE tasks enqueued */ @@ -9721,7 +9722,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX; unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0; unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024; - struct root_domain *rd = this_rq()->rd; + struct root_domain *rd = rcu_dereference_root_domain(this_rq()->rd); int cpu, best_energy_cpu, target = -1; int prev_fits = -1, best_fits = -1; unsigned long best_actual_cap = 0; @@ -9925,7 +9926,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags) cpumask_test_cpu(cpu, p->cpus_ptr)) return cpu; - if (!is_rd_overutilized(this_rq()->rd)) { + if (!is_rd_overutilized(rcu_dereference_root_domain(this_rq()->rd))) { new_cpu = find_energy_efficient_cpu(p, prev_cpu); if (new_cpu >= 0) return new_cpu; @@ -12974,13 +12975,15 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd env->fbq_type = fbq_classify_group(&sds->busiest_stat); if (!env->sd->parent) { + struct root_domain *rd = rcu_dereference_root_domain(env->dst_rq->rd); + /* update overload indicator if we are at root domain */ - set_rd_overloaded(env->dst_rq->rd, sg_overloaded); + set_rd_overloaded(rd, sg_overloaded); /* Update over-utilization (tipping point, U >= 0) indicator */ - set_rd_overutilized(env->dst_rq->rd, sg_overutilized); + set_rd_overutilized(rd, sg_overutilized); } else if (sg_overutilized) { - set_rd_overutilized(env->dst_rq->rd, sg_overutilized); + set_rd_overutilized(rcu_dereference_root_domain(env->dst_rq->rd), sg_overutilized); } update_idle_cpu_scan(env, sum_util); @@ -13226,8 +13229,10 @@ static struct sched_group *sched_balance_find_src_group(struct lb_env *env) if (busiest->group_type == group_misfit_task) goto force_balance; - if (!is_rd_overutilized(env->dst_rq->rd) && - rcu_dereference_all(env->dst_rq->rd->pd)) + struct root_domain *rd = rcu_dereference_root_domain(env->dst_rq->rd); + + if (rd && !is_rd_overutilized(rd) && + rcu_dereference_all(rd->pd)) goto out_balanced; /* ASYM feature bypasses nice load balance check */ @@ -14879,7 +14884,7 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) if (!sd) goto out; - if (!get_rd_overloaded(this_rq->rd) || + if (!get_rd_overloaded(rcu_dereference_root_domain(this_rq->rd)) || this_rq->avg_idle < sd->max_newidle_lb_cost) { update_next_balance(sd, &next_balance); diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 1535046a23ff..7ee86b65bf05 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -338,15 +338,18 @@ static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev) static inline int rt_overloaded(struct rq *rq) { - return atomic_read(&rq->rd->rto_count); + return atomic_read(&rcu_dereference_root_domain(rq->rd)->rto_count); } static inline void rt_set_overload(struct rq *rq) { + struct root_domain *rd; + if (!rq->online) return; - cpumask_set_cpu(rq->cpu, rq->rd->rto_mask); + rd = rcu_dereference_root_domain(rq->rd); + cpumask_set_cpu(rq->cpu, rd->rto_mask); /* * Make sure the mask is visible before we set * the overload count. That is checked to determine @@ -357,17 +360,20 @@ static inline void rt_set_overload(struct rq *rq) * Matched by the barrier in pull_rt_task(). */ smp_wmb(); - atomic_inc(&rq->rd->rto_count); + atomic_inc(&rd->rto_count); } static inline void rt_clear_overload(struct rq *rq) { + struct root_domain *rd; + if (!rq->online) return; + rd = rcu_dereference_root_domain(rq->rd); /* the order here really doesn't matter */ - atomic_dec(&rq->rd->rto_count); - cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask); + atomic_dec(&rd->rto_count); + cpumask_clear_cpu(rq->cpu, rd->rto_mask); } static inline int has_pushable_tasks(struct rq *rq) @@ -580,7 +586,7 @@ static int rt_se_boosted(struct sched_rt_entity *rt_se) static inline const struct cpumask *sched_rt_period_mask(void) { - return this_rq()->rd->span; + return rcu_dereference_root_domain(this_rq()->rd)->span; } static inline @@ -608,7 +614,7 @@ bool sched_rt_bandwidth_account(struct rt_rq *rt_rq) static void do_balance_runtime(struct rt_rq *rt_rq) { struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); - struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd; + struct root_domain *rd = rcu_dereference_root_domain(rq_of_rt_rq(rt_rq)->rd); int i, weight; u64 rt_period; @@ -659,7 +665,7 @@ static void do_balance_runtime(struct rt_rq *rt_rq) */ static void __disable_runtime(struct rq *rq) { - struct root_domain *rd = rq->rd; + struct root_domain *rd = rcu_dereference_root_domain(rq->rd); rt_rq_iter_t iter; struct rt_rq *rt_rq; @@ -1058,7 +1064,7 @@ inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) return; if (rq->online && prio < prev_prio) - cpupri_set(&rq->rd->cpupri, rq->cpu, prio); + cpupri_set(&rcu_dereference_root_domain(rq->rd)->cpupri, rq->cpu, prio); } static void @@ -1073,7 +1079,8 @@ dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) return; if (rq->online && rt_rq->highest_prio.curr != prev_prio) - cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr); + cpupri_set(&rcu_dereference_root_domain(rq->rd)->cpupri, rq->cpu, + rt_rq->highest_prio.curr); } static void @@ -1575,8 +1582,10 @@ select_task_rq_rt(struct task_struct *p, int cpu, int flags) static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) { + struct root_domain *rd = rcu_dereference_root_domain(rq->rd); + if (rq->curr->nr_cpus_allowed == 1 || - !cpupri_find(&rq->rd->cpupri, rq->donor, NULL)) + !cpupri_find(&rd->cpupri, rq->donor, NULL)) return; /* @@ -1584,7 +1593,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) * see if it is pushed or pulled somewhere else. */ if (p->nr_cpus_allowed != 1 && - cpupri_find(&rq->rd->cpupri, p, NULL)) + cpupri_find(&rd->cpupri, p, NULL)) return; /* @@ -1796,12 +1805,12 @@ static int find_lowest_rq(struct task_struct *task) */ if (sched_asym_cpucap_active()) { - ret = cpupri_find_fitness(&task_rq(task)->rd->cpupri, + ret = cpupri_find_fitness(&rcu_dereference_root_domain(task_rq(task)->rd)->cpupri, task, lowest_mask, rt_task_fits_capacity); } else { - ret = cpupri_find(&task_rq(task)->rd->cpupri, + ret = cpupri_find(&rcu_dereference_root_domain(task_rq(task)->rd)->cpupri, task, lowest_mask); } @@ -2192,16 +2201,17 @@ static inline void rto_start_unlock(atomic_t *v) static void tell_cpu_to_push(struct rq *rq) { + struct root_domain *rd = rcu_dereference_root_domain(rq->rd); int cpu = -1; /* Keep the loop going if the IPI is currently active */ - atomic_inc(&rq->rd->rto_loop_next); + atomic_inc(&rd->rto_loop_next); /* Only one CPU can initiate a loop at a time */ - if (!rto_start_trylock(&rq->rd->rto_loop_start)) + if (!rto_start_trylock(&rd->rto_loop_start)) return; - raw_spin_lock(&rq->rd->rto_lock); + raw_spin_lock(&rd->rto_lock); /* * The rto_cpu is updated under the lock, if it has a valid CPU @@ -2209,17 +2219,17 @@ static void tell_cpu_to_push(struct rq *rq) * update to loop_next, and nothing needs to be done here. * Otherwise it is finishing up and an IPI needs to be sent. */ - if (rq->rd->rto_cpu < 0) - cpu = rto_next_cpu(rq->rd); + if (rd->rto_cpu < 0) + cpu = rto_next_cpu(rd); - raw_spin_unlock(&rq->rd->rto_lock); + raw_spin_unlock(&rd->rto_lock); - rto_start_unlock(&rq->rd->rto_loop_start); + rto_start_unlock(&rd->rto_loop_start); if (cpu >= 0) { /* Make sure the rd does not get freed while pushing */ - sched_get_rd(rq->rd); - irq_work_queue_on(&rq->rd->rto_push_work, cpu); + sched_get_rd(rd); + irq_work_queue_on(&rd->rto_push_work, cpu); } } @@ -2280,7 +2290,7 @@ static void pull_rt_task(struct rq *this_rq) /* If we are the only overloaded CPU do nothing */ if (rt_overload_count == 1 && - cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask)) + cpumask_test_cpu(this_rq->cpu, rcu_dereference_root_domain(this_rq->rd)->rto_mask)) return; #ifdef HAVE_RT_PUSH_IPI @@ -2290,7 +2300,7 @@ static void pull_rt_task(struct rq *this_rq) } #endif - for_each_cpu(cpu, this_rq->rd->rto_mask) { + for_each_cpu(cpu, rcu_dereference_root_domain(this_rq->rd)->rto_mask) { if (this_cpu == cpu) continue; @@ -2395,7 +2405,7 @@ static void rq_online_rt(struct rq *rq) __enable_runtime(rq); - cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr); + cpupri_set(&rcu_dereference_root_domain(rq->rd)->cpupri, rq->cpu, rq->rt.highest_prio.curr); } /* Assumes rq->lock is held */ @@ -2406,7 +2416,7 @@ static void rq_offline_rt(struct rq *rq) __disable_runtime(rq); - cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID); + cpupri_set(&rcu_dereference_root_domain(rq->rd)->cpupri, rq->cpu, CPUPRI_INVALID); } /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 7d2ec527b8a2..6607963efa30 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1277,7 +1277,7 @@ struct rq { int membarrier_state; #endif - struct root_domain *rd; + struct root_domain __rcu *rd; struct sched_domain __rcu *sd; struct balance_callback *balance_callback; @@ -2167,6 +2167,9 @@ queue_balance_callback(struct rq *rq, rq->balance_callback = head; } +#define rcu_dereference_root_domain(p) \ + rcu_dereference_all_check((p), lockdep_is_held(&sched_domains_mutex)) + #define rcu_dereference_sched_domain(p) \ rcu_dereference_all_check((p), lockdep_is_held(&sched_domains_mutex)) @@ -3083,7 +3086,7 @@ static inline void add_nr_running(struct rq *rq, unsigned count) } if (prev_nr < 2 && rq->nr_running >= 2) - set_rd_overloaded(rq->rd, 1); + set_rd_overloaded(rcu_dereference_root_domain(rq->rd), 1); sched_update_tick_dependency(rq); } diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c index b215b0ead9a6..89a2465727fd 100644 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -621,15 +621,15 @@ int __sched_setscheduler(struct task_struct *p, #endif /* CONFIG_RT_GROUP_SCHED */ if (dl_bandwidth_enabled() && dl_policy(policy) && !(attr->sched_flags & SCHED_FLAG_SUGOV)) { - cpumask_t *span = rq->rd->span; + struct root_domain *rd = rcu_dereference_root_domain(rq->rd); /* * Don't allow tasks with an affinity mask smaller than * the entire root_domain to become SCHED_DEADLINE. We * will also fail if there's no bandwidth available. */ - if (!cpumask_subset(span, p->cpus_ptr) || - rq->rd->dl_bw.bw == 0) { + if (!cpumask_subset(rd->span, p->cpus_ptr) || + rd->dl_bw.bw == 0) { retval = -EPERM; goto unlock; } @@ -1127,7 +1127,7 @@ int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask) * root_domain. */ guard(rcu)(); - if (!cpumask_subset(task_rq(p)->rd->span, mask)) + if (!cpumask_subset(rcu_dereference_root_domain(task_rq(p)->rd)->span, mask)) return -EBUSY; return 0; diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 919d0fb00bd9..2db05acf12aa 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -427,7 +427,7 @@ static bool build_perf_domains(const struct cpumask *cpu_map) int i; struct perf_domain *pd = NULL, *tmp; int cpu = cpumask_first(cpu_map); - struct root_domain *rd = cpu_rq(cpu)->rd; + struct root_domain *rd = rcu_dereference_root_domain(cpu_rq(cpu)->rd); if (!sysctl_sched_energy_aware) goto free; @@ -492,9 +492,8 @@ void rq_attach_root(struct rq *rq, struct root_domain *rd) rq_lock_irqsave(rq, &rf); - if (rq->rd) { - old_rd = rq->rd; - + old_rd = rcu_dereference_root_domain(rq->rd); + if (old_rd) { if (cpumask_test_cpu(rq->cpu, old_rd->online)) set_rq_offline(rq); @@ -510,7 +509,7 @@ void rq_attach_root(struct rq *rq, struct root_domain *rd) } atomic_inc(&rd->refcount); - rq->rd = rd; + rcu_assign_pointer(rq->rd, rd); cpumask_set_cpu(rq->cpu, rd->span); if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) @@ -3483,8 +3482,10 @@ static void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new /* Build perf domains: */ for (i = 0; i < ndoms_new; i++) { for (j = 0; j < n && !sched_energy_update; j++) { + int cpu = cpumask_first(doms_cur[j]); + if (cpumask_equal(doms_new[i], doms_cur[j]) && - cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) { + rcu_dereference_root_domain(cpu_rq(cpu)->rd)->pd) { has_eas = true; goto match3; } -- 2.55.0