#include "../locking/rtmutex_common.h"
-#ifdef CONFIG_RCU_NOCB_CPU
-static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
-static bool __read_mostly rcu_nocb_poll; /* Offload kthread are to poll. */
-static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)
-{
- return lockdep_is_held(&rdp->nocb_lock);
-}
-
-static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)
-{
- /* Race on early boot between thread creation and assignment */
- if (!rdp->nocb_cb_kthread || !rdp->nocb_gp_kthread)
- return true;
-
- if (current == rdp->nocb_cb_kthread || current == rdp->nocb_gp_kthread)
- if (in_task())
- return true;
- return false;
-}
-
-#else
-static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)
-{
- return 0;
-}
-
-static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)
-{
- return false;
-}
-
-#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
-
static bool rcu_rdp_is_offloaded(struct rcu_data *rdp)
{
/*
trace_rcu_utilization(TPS("Start context switch"));
lockdep_assert_irqs_disabled();
- WARN_ON_ONCE(!preempt && rcu_preempt_depth() > 0);
+ WARN_ONCE(!preempt && rcu_preempt_depth() > 0, "Voluntary context switch within RCU read-side critical section!");
if (rcu_preempt_depth() > 0 &&
!t->rcu_read_unlock_special.b.blocked) {
static void rcu_preempt_read_enter(void)
{
- current->rcu_read_lock_nesting++;
+ WRITE_ONCE(current->rcu_read_lock_nesting, READ_ONCE(current->rcu_read_lock_nesting) + 1);
}
static int rcu_preempt_read_exit(void)
{
- return --current->rcu_read_lock_nesting;
+ int ret = READ_ONCE(current->rcu_read_lock_nesting) - 1;
+
+ WRITE_ONCE(current->rcu_read_lock_nesting, ret);
+ return ret;
}
static void rcu_preempt_depth_set(int val)
{
- current->rcu_read_lock_nesting = val;
+ WRITE_ONCE(current->rcu_read_lock_nesting, val);
}
/*
WRITE_ONCE(rnp->exp_tasks, np);
if (IS_ENABLED(CONFIG_RCU_BOOST)) {
/* Snapshot ->boost_mtx ownership w/rnp->lock held. */
- drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx) == t;
+ drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx.rtmutex) == t;
if (&t->rcu_node_entry == rnp->boost_tasks)
WRITE_ONCE(rnp->boost_tasks, np);
}
/* Unboost if we were boosted. */
if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
- rt_mutex_futex_unlock(&rnp->boost_mtx);
+ rt_mutex_futex_unlock(&rnp->boost_mtx.rtmutex);
/*
* If this was the last task on the expedited lists,
* section.
*/
t = container_of(tb, struct task_struct, rcu_node_entry);
- rt_mutex_init_proxy_locked(&rnp->boost_mtx, t);
+ rt_mutex_init_proxy_locked(&rnp->boost_mtx.rtmutex, t);
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/* Lock only for side effect: boosts task t's priority. */
rt_mutex_lock(&rnp->boost_mtx);
#endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */
-#ifdef CONFIG_RCU_NOCB_CPU
-
-/*
- * Offload callback processing from the boot-time-specified set of CPUs
- * specified by rcu_nocb_mask. For the CPUs in the set, there are kthreads
- * created that pull the callbacks from the corresponding CPU, wait for
- * a grace period to elapse, and invoke the callbacks. These kthreads
- * are organized into GP kthreads, which manage incoming callbacks, wait for
- * grace periods, and awaken CB kthreads, and the CB kthreads, which only
- * invoke callbacks. Each GP kthread invokes its own CBs. The no-CBs CPUs
- * do a wake_up() on their GP kthread when they insert a callback into any
- * empty list, unless the rcu_nocb_poll boot parameter has been specified,
- * in which case each kthread actively polls its CPU. (Which isn't so great
- * for energy efficiency, but which does reduce RCU's overhead on that CPU.)
- *
- * This is intended to be used in conjunction with Frederic Weisbecker's
- * adaptive-idle work, which would seriously reduce OS jitter on CPUs
- * running CPU-bound user-mode computations.
- *
- * Offloading of callbacks can also be used as an energy-efficiency
- * measure because CPUs with no RCU callbacks queued are more aggressive
- * about entering dyntick-idle mode.
- */
-
-
-/*
- * Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters.
- * If the list is invalid, a warning is emitted and all CPUs are offloaded.
- */
-static int __init rcu_nocb_setup(char *str)
-{
- alloc_bootmem_cpumask_var(&rcu_nocb_mask);
- if (cpulist_parse(str, rcu_nocb_mask)) {
- pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n");
- cpumask_setall(rcu_nocb_mask);
- }
- return 1;
-}
-__setup("rcu_nocbs=", rcu_nocb_setup);
-
-static int __init parse_rcu_nocb_poll(char *arg)
-{
- rcu_nocb_poll = true;
- return 0;
-}
-early_param("rcu_nocb_poll", parse_rcu_nocb_poll);
-
-/*
- * Don't bother bypassing ->cblist if the call_rcu() rate is low.
- * After all, the main point of bypassing is to avoid lock contention
- * on ->nocb_lock, which only can happen at high call_rcu() rates.
- */
-static int nocb_nobypass_lim_per_jiffy = 16 * 1000 / HZ;
-module_param(nocb_nobypass_lim_per_jiffy, int, 0);
-
-/*
- * Acquire the specified rcu_data structure's ->nocb_bypass_lock. If the
- * lock isn't immediately available, increment ->nocb_lock_contended to
- * flag the contention.
- */
-static void rcu_nocb_bypass_lock(struct rcu_data *rdp)
- __acquires(&rdp->nocb_bypass_lock)
-{
- lockdep_assert_irqs_disabled();
- if (raw_spin_trylock(&rdp->nocb_bypass_lock))
- return;
- atomic_inc(&rdp->nocb_lock_contended);
- WARN_ON_ONCE(smp_processor_id() != rdp->cpu);
- smp_mb__after_atomic(); /* atomic_inc() before lock. */
- raw_spin_lock(&rdp->nocb_bypass_lock);
- smp_mb__before_atomic(); /* atomic_dec() after lock. */
- atomic_dec(&rdp->nocb_lock_contended);
-}
-
-/*
- * Spinwait until the specified rcu_data structure's ->nocb_lock is
- * not contended. Please note that this is extremely special-purpose,
- * relying on the fact that at most two kthreads and one CPU contend for
- * this lock, and also that the two kthreads are guaranteed to have frequent
- * grace-period-duration time intervals between successive acquisitions
- * of the lock. This allows us to use an extremely simple throttling
- * mechanism, and further to apply it only to the CPU doing floods of
- * call_rcu() invocations. Don't try this at home!
- */
-static void rcu_nocb_wait_contended(struct rcu_data *rdp)
-{
- WARN_ON_ONCE(smp_processor_id() != rdp->cpu);
- while (WARN_ON_ONCE(atomic_read(&rdp->nocb_lock_contended)))
- cpu_relax();
-}
-
-/*
- * Conditionally acquire the specified rcu_data structure's
- * ->nocb_bypass_lock.
- */
-static bool rcu_nocb_bypass_trylock(struct rcu_data *rdp)
-{
- lockdep_assert_irqs_disabled();
- return raw_spin_trylock(&rdp->nocb_bypass_lock);
-}
-
-/*
- * Release the specified rcu_data structure's ->nocb_bypass_lock.
- */
-static void rcu_nocb_bypass_unlock(struct rcu_data *rdp)
- __releases(&rdp->nocb_bypass_lock)
-{
- lockdep_assert_irqs_disabled();
- raw_spin_unlock(&rdp->nocb_bypass_lock);
-}
-
-/*
- * Acquire the specified rcu_data structure's ->nocb_lock, but only
- * if it corresponds to a no-CBs CPU.
- */
-static void rcu_nocb_lock(struct rcu_data *rdp)
-{
- lockdep_assert_irqs_disabled();
- if (!rcu_rdp_is_offloaded(rdp))
- return;
- raw_spin_lock(&rdp->nocb_lock);
-}
-
-/*
- * Release the specified rcu_data structure's ->nocb_lock, but only
- * if it corresponds to a no-CBs CPU.
- */
-static void rcu_nocb_unlock(struct rcu_data *rdp)
-{
- if (rcu_rdp_is_offloaded(rdp)) {
- lockdep_assert_irqs_disabled();
- raw_spin_unlock(&rdp->nocb_lock);
- }
-}
-
-/*
- * Release the specified rcu_data structure's ->nocb_lock and restore
- * interrupts, but only if it corresponds to a no-CBs CPU.
- */
-static void rcu_nocb_unlock_irqrestore(struct rcu_data *rdp,
- unsigned long flags)
-{
- if (rcu_rdp_is_offloaded(rdp)) {
- lockdep_assert_irqs_disabled();
- raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
- } else {
- local_irq_restore(flags);
- }
-}
-
-/* Lockdep check that ->cblist may be safely accessed. */
-static void rcu_lockdep_assert_cblist_protected(struct rcu_data *rdp)
-{
- lockdep_assert_irqs_disabled();
- if (rcu_rdp_is_offloaded(rdp))
- lockdep_assert_held(&rdp->nocb_lock);
-}
-
-/*
- * Wake up any no-CBs CPUs' kthreads that were waiting on the just-ended
- * grace period.
- */
-static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq)
-{
- swake_up_all(sq);
-}
-
-static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp)
-{
- return &rnp->nocb_gp_wq[rcu_seq_ctr(rnp->gp_seq) & 0x1];
-}
-
-static void rcu_init_one_nocb(struct rcu_node *rnp)
-{
- init_swait_queue_head(&rnp->nocb_gp_wq[0]);
- init_swait_queue_head(&rnp->nocb_gp_wq[1]);
-}
-
-/* Is the specified CPU a no-CBs CPU? */
-bool rcu_is_nocb_cpu(int cpu)
-{
- if (cpumask_available(rcu_nocb_mask))
- return cpumask_test_cpu(cpu, rcu_nocb_mask);
- return false;
-}
-
-static bool __wake_nocb_gp(struct rcu_data *rdp_gp,
- struct rcu_data *rdp,
- bool force, unsigned long flags)
- __releases(rdp_gp->nocb_gp_lock)
-{
- bool needwake = false;
-
- if (!READ_ONCE(rdp_gp->nocb_gp_kthread)) {
- raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("AlreadyAwake"));
- return false;
- }
-
- if (rdp_gp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {
- WRITE_ONCE(rdp_gp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
- del_timer(&rdp_gp->nocb_timer);
- }
-
- if (force || READ_ONCE(rdp_gp->nocb_gp_sleep)) {
- WRITE_ONCE(rdp_gp->nocb_gp_sleep, false);
- needwake = true;
- }
- raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
- if (needwake) {
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DoWake"));
- wake_up_process(rdp_gp->nocb_gp_kthread);
- }
-
- return needwake;
-}
-
-/*
- * Kick the GP kthread for this NOCB group.
- */
-static bool wake_nocb_gp(struct rcu_data *rdp, bool force)
-{
- unsigned long flags;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
-
- raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
- return __wake_nocb_gp(rdp_gp, rdp, force, flags);
-}
-
-/*
- * Arrange to wake the GP kthread for this NOCB group at some future
- * time when it is safe to do so.
- */
-static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype,
- const char *reason)
-{
- unsigned long flags;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
-
- raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
-
- /*
- * Bypass wakeup overrides previous deferments. In case
- * of callback storm, no need to wake up too early.
- */
- if (waketype == RCU_NOCB_WAKE_BYPASS) {
- mod_timer(&rdp_gp->nocb_timer, jiffies + 2);
- WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
- } else {
- if (rdp_gp->nocb_defer_wakeup < RCU_NOCB_WAKE)
- mod_timer(&rdp_gp->nocb_timer, jiffies + 1);
- if (rdp_gp->nocb_defer_wakeup < waketype)
- WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
- }
-
- raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
-
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, reason);
-}
-
-/*
- * Flush the ->nocb_bypass queue into ->cblist, enqueuing rhp if non-NULL.
- * However, if there is a callback to be enqueued and if ->nocb_bypass
- * proves to be initially empty, just return false because the no-CB GP
- * kthread may need to be awakened in this case.
- *
- * Note that this function always returns true if rhp is NULL.
- */
-static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
- unsigned long j)
-{
- struct rcu_cblist rcl;
-
- WARN_ON_ONCE(!rcu_rdp_is_offloaded(rdp));
- rcu_lockdep_assert_cblist_protected(rdp);
- lockdep_assert_held(&rdp->nocb_bypass_lock);
- if (rhp && !rcu_cblist_n_cbs(&rdp->nocb_bypass)) {
- raw_spin_unlock(&rdp->nocb_bypass_lock);
- return false;
- }
- /* Note: ->cblist.len already accounts for ->nocb_bypass contents. */
- if (rhp)
- rcu_segcblist_inc_len(&rdp->cblist); /* Must precede enqueue. */
- rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp);
- rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rcl);
- WRITE_ONCE(rdp->nocb_bypass_first, j);
- rcu_nocb_bypass_unlock(rdp);
- return true;
-}
-
-/*
- * Flush the ->nocb_bypass queue into ->cblist, enqueuing rhp if non-NULL.
- * However, if there is a callback to be enqueued and if ->nocb_bypass
- * proves to be initially empty, just return false because the no-CB GP
- * kthread may need to be awakened in this case.
- *
- * Note that this function always returns true if rhp is NULL.
- */
-static bool rcu_nocb_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
- unsigned long j)
-{
- if (!rcu_rdp_is_offloaded(rdp))
- return true;
- rcu_lockdep_assert_cblist_protected(rdp);
- rcu_nocb_bypass_lock(rdp);
- return rcu_nocb_do_flush_bypass(rdp, rhp, j);
-}
-
-/*
- * If the ->nocb_bypass_lock is immediately available, flush the
- * ->nocb_bypass queue into ->cblist.
- */
-static void rcu_nocb_try_flush_bypass(struct rcu_data *rdp, unsigned long j)
-{
- rcu_lockdep_assert_cblist_protected(rdp);
- if (!rcu_rdp_is_offloaded(rdp) ||
- !rcu_nocb_bypass_trylock(rdp))
- return;
- WARN_ON_ONCE(!rcu_nocb_do_flush_bypass(rdp, NULL, j));
-}
-
-/*
- * See whether it is appropriate to use the ->nocb_bypass list in order
- * to control contention on ->nocb_lock. A limited number of direct
- * enqueues are permitted into ->cblist per jiffy. If ->nocb_bypass
- * is non-empty, further callbacks must be placed into ->nocb_bypass,
- * otherwise rcu_barrier() breaks. Use rcu_nocb_flush_bypass() to switch
- * back to direct use of ->cblist. However, ->nocb_bypass should not be
- * used if ->cblist is empty, because otherwise callbacks can be stranded
- * on ->nocb_bypass because we cannot count on the current CPU ever again
- * invoking call_rcu(). The general rule is that if ->nocb_bypass is
- * non-empty, the corresponding no-CBs grace-period kthread must not be
- * in an indefinite sleep state.
- *
- * Finally, it is not permitted to use the bypass during early boot,
- * as doing so would confuse the auto-initialization code. Besides
- * which, there is no point in worrying about lock contention while
- * there is only one CPU in operation.
- */
-static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
- bool *was_alldone, unsigned long flags)
-{
- unsigned long c;
- unsigned long cur_gp_seq;
- unsigned long j = jiffies;
- long ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
-
- lockdep_assert_irqs_disabled();
-
- // Pure softirq/rcuc based processing: no bypassing, no
- // locking.
- if (!rcu_rdp_is_offloaded(rdp)) {
- *was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
- return false;
- }
-
- // In the process of (de-)offloading: no bypassing, but
- // locking.
- if (!rcu_segcblist_completely_offloaded(&rdp->cblist)) {
- rcu_nocb_lock(rdp);
- *was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
- return false; /* Not offloaded, no bypassing. */
- }
-
- // Don't use ->nocb_bypass during early boot.
- if (rcu_scheduler_active != RCU_SCHEDULER_RUNNING) {
- rcu_nocb_lock(rdp);
- WARN_ON_ONCE(rcu_cblist_n_cbs(&rdp->nocb_bypass));
- *was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
- return false;
- }
-
- // If we have advanced to a new jiffy, reset counts to allow
- // moving back from ->nocb_bypass to ->cblist.
- if (j == rdp->nocb_nobypass_last) {
- c = rdp->nocb_nobypass_count + 1;
- } else {
- WRITE_ONCE(rdp->nocb_nobypass_last, j);
- c = rdp->nocb_nobypass_count - nocb_nobypass_lim_per_jiffy;
- if (ULONG_CMP_LT(rdp->nocb_nobypass_count,
- nocb_nobypass_lim_per_jiffy))
- c = 0;
- else if (c > nocb_nobypass_lim_per_jiffy)
- c = nocb_nobypass_lim_per_jiffy;
- }
- WRITE_ONCE(rdp->nocb_nobypass_count, c);
-
- // If there hasn't yet been all that many ->cblist enqueues
- // this jiffy, tell the caller to enqueue onto ->cblist. But flush
- // ->nocb_bypass first.
- if (rdp->nocb_nobypass_count < nocb_nobypass_lim_per_jiffy) {
- rcu_nocb_lock(rdp);
- *was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
- if (*was_alldone)
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("FirstQ"));
- WARN_ON_ONCE(!rcu_nocb_flush_bypass(rdp, NULL, j));
- WARN_ON_ONCE(rcu_cblist_n_cbs(&rdp->nocb_bypass));
- return false; // Caller must enqueue the callback.
- }
-
- // If ->nocb_bypass has been used too long or is too full,
- // flush ->nocb_bypass to ->cblist.
- if ((ncbs && j != READ_ONCE(rdp->nocb_bypass_first)) ||
- ncbs >= qhimark) {
- rcu_nocb_lock(rdp);
- if (!rcu_nocb_flush_bypass(rdp, rhp, j)) {
- *was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
- if (*was_alldone)
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("FirstQ"));
- WARN_ON_ONCE(rcu_cblist_n_cbs(&rdp->nocb_bypass));
- return false; // Caller must enqueue the callback.
- }
- if (j != rdp->nocb_gp_adv_time &&
- rcu_segcblist_nextgp(&rdp->cblist, &cur_gp_seq) &&
- rcu_seq_done(&rdp->mynode->gp_seq, cur_gp_seq)) {
- rcu_advance_cbs_nowake(rdp->mynode, rdp);
- rdp->nocb_gp_adv_time = j;
- }
- rcu_nocb_unlock_irqrestore(rdp, flags);
- return true; // Callback already enqueued.
- }
-
- // We need to use the bypass.
- rcu_nocb_wait_contended(rdp);
- rcu_nocb_bypass_lock(rdp);
- ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
- rcu_segcblist_inc_len(&rdp->cblist); /* Must precede enqueue. */
- rcu_cblist_enqueue(&rdp->nocb_bypass, rhp);
- if (!ncbs) {
- WRITE_ONCE(rdp->nocb_bypass_first, j);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("FirstBQ"));
- }
- rcu_nocb_bypass_unlock(rdp);
- smp_mb(); /* Order enqueue before wake. */
- if (ncbs) {
- local_irq_restore(flags);
- } else {
- // No-CBs GP kthread might be indefinitely asleep, if so, wake.
- rcu_nocb_lock(rdp); // Rare during call_rcu() flood.
- if (!rcu_segcblist_pend_cbs(&rdp->cblist)) {
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("FirstBQwake"));
- __call_rcu_nocb_wake(rdp, true, flags);
- } else {
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("FirstBQnoWake"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
- }
- }
- return true; // Callback already enqueued.
-}
-
-/*
- * Awaken the no-CBs grace-period kthread if needed, either due to it
- * legitimately being asleep or due to overload conditions.
- *
- * If warranted, also wake up the kthread servicing this CPUs queues.
- */
-static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
- unsigned long flags)
- __releases(rdp->nocb_lock)
-{
- unsigned long cur_gp_seq;
- unsigned long j;
- long len;
- struct task_struct *t;
-
- // If we are being polled or there is no kthread, just leave.
- t = READ_ONCE(rdp->nocb_gp_kthread);
- if (rcu_nocb_poll || !t) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("WakeNotPoll"));
- return;
- }
- // Need to actually to a wakeup.
- len = rcu_segcblist_n_cbs(&rdp->cblist);
- if (was_alldone) {
- rdp->qlen_last_fqs_check = len;
- if (!irqs_disabled_flags(flags)) {
- /* ... if queue was empty ... */
- rcu_nocb_unlock_irqrestore(rdp, flags);
- wake_nocb_gp(rdp, false);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("WakeEmpty"));
- } else {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE,
- TPS("WakeEmptyIsDeferred"));
- }
- } else if (len > rdp->qlen_last_fqs_check + qhimark) {
- /* ... or if many callbacks queued. */
- rdp->qlen_last_fqs_check = len;
- j = jiffies;
- if (j != rdp->nocb_gp_adv_time &&
- rcu_segcblist_nextgp(&rdp->cblist, &cur_gp_seq) &&
- rcu_seq_done(&rdp->mynode->gp_seq, cur_gp_seq)) {
- rcu_advance_cbs_nowake(rdp->mynode, rdp);
- rdp->nocb_gp_adv_time = j;
- }
- smp_mb(); /* Enqueue before timer_pending(). */
- if ((rdp->nocb_cb_sleep ||
- !rcu_segcblist_ready_cbs(&rdp->cblist)) &&
- !timer_pending(&rdp->nocb_timer)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE_FORCE,
- TPS("WakeOvfIsDeferred"));
- } else {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
- }
- } else {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
- }
- return;
-}
-
-/*
- * Check if we ignore this rdp.
- *
- * We check that without holding the nocb lock but
- * we make sure not to miss a freshly offloaded rdp
- * with the current ordering:
- *
- * rdp_offload_toggle() nocb_gp_enabled_cb()
- * ------------------------- ----------------------------
- * WRITE flags LOCK nocb_gp_lock
- * LOCK nocb_gp_lock READ/WRITE nocb_gp_sleep
- * READ/WRITE nocb_gp_sleep UNLOCK nocb_gp_lock
- * UNLOCK nocb_gp_lock READ flags
- */
-static inline bool nocb_gp_enabled_cb(struct rcu_data *rdp)
-{
- u8 flags = SEGCBLIST_OFFLOADED | SEGCBLIST_KTHREAD_GP;
-
- return rcu_segcblist_test_flags(&rdp->cblist, flags);
-}
-
-static inline bool nocb_gp_update_state_deoffloading(struct rcu_data *rdp,
- bool *needwake_state)
-{
- struct rcu_segcblist *cblist = &rdp->cblist;
-
- if (rcu_segcblist_test_flags(cblist, SEGCBLIST_OFFLOADED)) {
- if (!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP)) {
- rcu_segcblist_set_flags(cblist, SEGCBLIST_KTHREAD_GP);
- if (rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB))
- *needwake_state = true;
- }
- return false;
- }
-
- /*
- * De-offloading. Clear our flag and notify the de-offload worker.
- * We will ignore this rdp until it ever gets re-offloaded.
- */
- WARN_ON_ONCE(!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP));
- rcu_segcblist_clear_flags(cblist, SEGCBLIST_KTHREAD_GP);
- if (!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB))
- *needwake_state = true;
- return true;
-}
-
-
-/*
- * No-CBs GP kthreads come here to wait for additional callbacks to show up
- * or for grace periods to end.
- */
-static void nocb_gp_wait(struct rcu_data *my_rdp)
-{
- bool bypass = false;
- long bypass_ncbs;
- int __maybe_unused cpu = my_rdp->cpu;
- unsigned long cur_gp_seq;
- unsigned long flags;
- bool gotcbs = false;
- unsigned long j = jiffies;
- bool needwait_gp = false; // This prevents actual uninitialized use.
- bool needwake;
- bool needwake_gp;
- struct rcu_data *rdp;
- struct rcu_node *rnp;
- unsigned long wait_gp_seq = 0; // Suppress "use uninitialized" warning.
- bool wasempty = false;
-
- /*
- * Each pass through the following loop checks for CBs and for the
- * nearest grace period (if any) to wait for next. The CB kthreads
- * and the global grace-period kthread are awakened if needed.
- */
- WARN_ON_ONCE(my_rdp->nocb_gp_rdp != my_rdp);
- for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) {
- bool needwake_state = false;
-
- if (!nocb_gp_enabled_cb(rdp))
- continue;
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
- rcu_nocb_lock_irqsave(rdp, flags);
- if (nocb_gp_update_state_deoffloading(rdp, &needwake_state)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- if (needwake_state)
- swake_up_one(&rdp->nocb_state_wq);
- continue;
- }
- bypass_ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
- if (bypass_ncbs &&
- (time_after(j, READ_ONCE(rdp->nocb_bypass_first) + 1) ||
- bypass_ncbs > 2 * qhimark)) {
- // Bypass full or old, so flush it.
- (void)rcu_nocb_try_flush_bypass(rdp, j);
- bypass_ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
- } else if (!bypass_ncbs && rcu_segcblist_empty(&rdp->cblist)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
- if (needwake_state)
- swake_up_one(&rdp->nocb_state_wq);
- continue; /* No callbacks here, try next. */
- }
- if (bypass_ncbs) {
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("Bypass"));
- bypass = true;
- }
- rnp = rdp->mynode;
-
- // Advance callbacks if helpful and low contention.
- needwake_gp = false;
- if (!rcu_segcblist_restempty(&rdp->cblist,
- RCU_NEXT_READY_TAIL) ||
- (rcu_segcblist_nextgp(&rdp->cblist, &cur_gp_seq) &&
- rcu_seq_done(&rnp->gp_seq, cur_gp_seq))) {
- raw_spin_lock_rcu_node(rnp); /* irqs disabled. */
- needwake_gp = rcu_advance_cbs(rnp, rdp);
- wasempty = rcu_segcblist_restempty(&rdp->cblist,
- RCU_NEXT_READY_TAIL);
- raw_spin_unlock_rcu_node(rnp); /* irqs disabled. */
- }
- // Need to wait on some grace period?
- WARN_ON_ONCE(wasempty &&
- !rcu_segcblist_restempty(&rdp->cblist,
- RCU_NEXT_READY_TAIL));
- if (rcu_segcblist_nextgp(&rdp->cblist, &cur_gp_seq)) {
- if (!needwait_gp ||
- ULONG_CMP_LT(cur_gp_seq, wait_gp_seq))
- wait_gp_seq = cur_gp_seq;
- needwait_gp = true;
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
- TPS("NeedWaitGP"));
- }
- if (rcu_segcblist_ready_cbs(&rdp->cblist)) {
- needwake = rdp->nocb_cb_sleep;
- WRITE_ONCE(rdp->nocb_cb_sleep, false);
- smp_mb(); /* CB invocation -after- GP end. */
- } else {
- needwake = false;
- }
- rcu_nocb_unlock_irqrestore(rdp, flags);
- if (needwake) {
- swake_up_one(&rdp->nocb_cb_wq);
- gotcbs = true;
- }
- if (needwake_gp)
- rcu_gp_kthread_wake();
- if (needwake_state)
- swake_up_one(&rdp->nocb_state_wq);
- }
-
- my_rdp->nocb_gp_bypass = bypass;
- my_rdp->nocb_gp_gp = needwait_gp;
- my_rdp->nocb_gp_seq = needwait_gp ? wait_gp_seq : 0;
-
- if (bypass && !rcu_nocb_poll) {
- // At least one child with non-empty ->nocb_bypass, so set
- // timer in order to avoid stranding its callbacks.
- wake_nocb_gp_defer(my_rdp, RCU_NOCB_WAKE_BYPASS,
- TPS("WakeBypassIsDeferred"));
- }
- if (rcu_nocb_poll) {
- /* Polling, so trace if first poll in the series. */
- if (gotcbs)
- trace_rcu_nocb_wake(rcu_state.name, cpu, TPS("Poll"));
- schedule_timeout_idle(1);
- } else if (!needwait_gp) {
- /* Wait for callbacks to appear. */
- trace_rcu_nocb_wake(rcu_state.name, cpu, TPS("Sleep"));
- swait_event_interruptible_exclusive(my_rdp->nocb_gp_wq,
- !READ_ONCE(my_rdp->nocb_gp_sleep));
- trace_rcu_nocb_wake(rcu_state.name, cpu, TPS("EndSleep"));
- } else {
- rnp = my_rdp->mynode;
- trace_rcu_this_gp(rnp, my_rdp, wait_gp_seq, TPS("StartWait"));
- swait_event_interruptible_exclusive(
- rnp->nocb_gp_wq[rcu_seq_ctr(wait_gp_seq) & 0x1],
- rcu_seq_done(&rnp->gp_seq, wait_gp_seq) ||
- !READ_ONCE(my_rdp->nocb_gp_sleep));
- trace_rcu_this_gp(rnp, my_rdp, wait_gp_seq, TPS("EndWait"));
- }
- if (!rcu_nocb_poll) {
- raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
- if (my_rdp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {
- WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
- del_timer(&my_rdp->nocb_timer);
- }
- WRITE_ONCE(my_rdp->nocb_gp_sleep, true);
- raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
- }
- my_rdp->nocb_gp_seq = -1;
- WARN_ON(signal_pending(current));
-}
-
-/*
- * No-CBs grace-period-wait kthread. There is one of these per group
- * of CPUs, but only once at least one CPU in that group has come online
- * at least once since boot. This kthread checks for newly posted
- * callbacks from any of the CPUs it is responsible for, waits for a
- * grace period, then awakens all of the rcu_nocb_cb_kthread() instances
- * that then have callback-invocation work to do.
- */
-static int rcu_nocb_gp_kthread(void *arg)
-{
- struct rcu_data *rdp = arg;
-
- for (;;) {
- WRITE_ONCE(rdp->nocb_gp_loops, rdp->nocb_gp_loops + 1);
- nocb_gp_wait(rdp);
- cond_resched_tasks_rcu_qs();
- }
- return 0;
-}
-
-static inline bool nocb_cb_can_run(struct rcu_data *rdp)
-{
- u8 flags = SEGCBLIST_OFFLOADED | SEGCBLIST_KTHREAD_CB;
- return rcu_segcblist_test_flags(&rdp->cblist, flags);
-}
-
-static inline bool nocb_cb_wait_cond(struct rcu_data *rdp)
-{
- return nocb_cb_can_run(rdp) && !READ_ONCE(rdp->nocb_cb_sleep);
-}
-
-/*
- * Invoke any ready callbacks from the corresponding no-CBs CPU,
- * then, if there are no more, wait for more to appear.
- */
-static void nocb_cb_wait(struct rcu_data *rdp)
-{
- struct rcu_segcblist *cblist = &rdp->cblist;
- unsigned long cur_gp_seq;
- unsigned long flags;
- bool needwake_state = false;
- bool needwake_gp = false;
- bool can_sleep = true;
- struct rcu_node *rnp = rdp->mynode;
-
- local_irq_save(flags);
- rcu_momentary_dyntick_idle();
- local_irq_restore(flags);
- /*
- * Disable BH to provide the expected environment. Also, when
- * transitioning to/from NOCB mode, a self-requeuing callback might
- * be invoked from softirq. A short grace period could cause both
- * instances of this callback would execute concurrently.
- */
- local_bh_disable();
- rcu_do_batch(rdp);
- local_bh_enable();
- lockdep_assert_irqs_enabled();
- rcu_nocb_lock_irqsave(rdp, flags);
- if (rcu_segcblist_nextgp(cblist, &cur_gp_seq) &&
- rcu_seq_done(&rnp->gp_seq, cur_gp_seq) &&
- raw_spin_trylock_rcu_node(rnp)) { /* irqs already disabled. */
- needwake_gp = rcu_advance_cbs(rdp->mynode, rdp);
- raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
- }
-
- if (rcu_segcblist_test_flags(cblist, SEGCBLIST_OFFLOADED)) {
- if (!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB)) {
- rcu_segcblist_set_flags(cblist, SEGCBLIST_KTHREAD_CB);
- if (rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP))
- needwake_state = true;
- }
- if (rcu_segcblist_ready_cbs(cblist))
- can_sleep = false;
- } else {
- /*
- * De-offloading. Clear our flag and notify the de-offload worker.
- * We won't touch the callbacks and keep sleeping until we ever
- * get re-offloaded.
- */
- WARN_ON_ONCE(!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB));
- rcu_segcblist_clear_flags(cblist, SEGCBLIST_KTHREAD_CB);
- if (!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP))
- needwake_state = true;
- }
-
- WRITE_ONCE(rdp->nocb_cb_sleep, can_sleep);
-
- if (rdp->nocb_cb_sleep)
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("CBSleep"));
-
- rcu_nocb_unlock_irqrestore(rdp, flags);
- if (needwake_gp)
- rcu_gp_kthread_wake();
-
- if (needwake_state)
- swake_up_one(&rdp->nocb_state_wq);
-
- do {
- swait_event_interruptible_exclusive(rdp->nocb_cb_wq,
- nocb_cb_wait_cond(rdp));
-
- // VVV Ensure CB invocation follows _sleep test.
- if (smp_load_acquire(&rdp->nocb_cb_sleep)) { // ^^^
- WARN_ON(signal_pending(current));
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WokeEmpty"));
- }
- } while (!nocb_cb_can_run(rdp));
-}
-
-/*
- * Per-rcu_data kthread, but only for no-CBs CPUs. Repeatedly invoke
- * nocb_cb_wait() to do the dirty work.
- */
-static int rcu_nocb_cb_kthread(void *arg)
-{
- struct rcu_data *rdp = arg;
-
- // Each pass through this loop does one callback batch, and,
- // if there are no more ready callbacks, waits for them.
- for (;;) {
- nocb_cb_wait(rdp);
- cond_resched_tasks_rcu_qs();
- }
- return 0;
-}
-
-/* Is a deferred wakeup of rcu_nocb_kthread() required? */
-static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level)
-{
- return READ_ONCE(rdp->nocb_defer_wakeup) >= level;
-}
-
-/* Do a deferred wakeup of rcu_nocb_kthread(). */
-static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp_gp,
- struct rcu_data *rdp, int level,
- unsigned long flags)
- __releases(rdp_gp->nocb_gp_lock)
-{
- int ndw;
- int ret;
-
- if (!rcu_nocb_need_deferred_wakeup(rdp_gp, level)) {
- raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
- return false;
- }
-
- ndw = rdp_gp->nocb_defer_wakeup;
- ret = __wake_nocb_gp(rdp_gp, rdp, ndw == RCU_NOCB_WAKE_FORCE, flags);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DeferredWake"));
-
- return ret;
-}
-
-/* Do a deferred wakeup of rcu_nocb_kthread() from a timer handler. */
-static void do_nocb_deferred_wakeup_timer(struct timer_list *t)
-{
- unsigned long flags;
- struct rcu_data *rdp = from_timer(rdp, t, nocb_timer);
-
- WARN_ON_ONCE(rdp->nocb_gp_rdp != rdp);
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Timer"));
-
- raw_spin_lock_irqsave(&rdp->nocb_gp_lock, flags);
- smp_mb__after_spinlock(); /* Timer expire before wakeup. */
- do_nocb_deferred_wakeup_common(rdp, rdp, RCU_NOCB_WAKE_BYPASS, flags);
-}
-
-/*
- * Do a deferred wakeup of rcu_nocb_kthread() from fastpath.
- * This means we do an inexact common-case check. Note that if
- * we miss, ->nocb_timer will eventually clean things up.
- */
-static bool do_nocb_deferred_wakeup(struct rcu_data *rdp)
-{
- unsigned long flags;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
-
- if (!rdp_gp || !rcu_nocb_need_deferred_wakeup(rdp_gp, RCU_NOCB_WAKE))
- return false;
-
- raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
- return do_nocb_deferred_wakeup_common(rdp_gp, rdp, RCU_NOCB_WAKE, flags);
-}
-
-void rcu_nocb_flush_deferred_wakeup(void)
-{
- do_nocb_deferred_wakeup(this_cpu_ptr(&rcu_data));
-}
-EXPORT_SYMBOL_GPL(rcu_nocb_flush_deferred_wakeup);
-
-static int rdp_offload_toggle(struct rcu_data *rdp,
- bool offload, unsigned long flags)
- __releases(rdp->nocb_lock)
-{
- struct rcu_segcblist *cblist = &rdp->cblist;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
- bool wake_gp = false;
-
- rcu_segcblist_offload(cblist, offload);
-
- if (rdp->nocb_cb_sleep)
- rdp->nocb_cb_sleep = false;
- rcu_nocb_unlock_irqrestore(rdp, flags);
-
- /*
- * Ignore former value of nocb_cb_sleep and force wake up as it could
- * have been spuriously set to false already.
- */
- swake_up_one(&rdp->nocb_cb_wq);
-
- raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
- if (rdp_gp->nocb_gp_sleep) {
- rdp_gp->nocb_gp_sleep = false;
- wake_gp = true;
- }
- raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
-
- if (wake_gp)
- wake_up_process(rdp_gp->nocb_gp_kthread);
-
- return 0;
-}
-
-static long rcu_nocb_rdp_deoffload(void *arg)
-{
- struct rcu_data *rdp = arg;
- struct rcu_segcblist *cblist = &rdp->cblist;
- unsigned long flags;
- int ret;
-
- WARN_ON_ONCE(rdp->cpu != raw_smp_processor_id());
-
- pr_info("De-offloading %d\n", rdp->cpu);
-
- rcu_nocb_lock_irqsave(rdp, flags);
- /*
- * Flush once and for all now. This suffices because we are
- * running on the target CPU holding ->nocb_lock (thus having
- * interrupts disabled), and because rdp_offload_toggle()
- * invokes rcu_segcblist_offload(), which clears SEGCBLIST_OFFLOADED.
- * Thus future calls to rcu_segcblist_completely_offloaded() will
- * return false, which means that future calls to rcu_nocb_try_bypass()
- * will refuse to put anything into the bypass.
- */
- WARN_ON_ONCE(!rcu_nocb_flush_bypass(rdp, NULL, jiffies));
- ret = rdp_offload_toggle(rdp, false, flags);
- swait_event_exclusive(rdp->nocb_state_wq,
- !rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB |
- SEGCBLIST_KTHREAD_GP));
- /*
- * Lock one last time to acquire latest callback updates from kthreads
- * so we can later handle callbacks locally without locking.
- */
- rcu_nocb_lock_irqsave(rdp, flags);
- /*
- * Theoretically we could set SEGCBLIST_SOFTIRQ_ONLY after the nocb
- * lock is released but how about being paranoid for once?
- */
- rcu_segcblist_set_flags(cblist, SEGCBLIST_SOFTIRQ_ONLY);
- /*
- * With SEGCBLIST_SOFTIRQ_ONLY, we can't use
- * rcu_nocb_unlock_irqrestore() anymore.
- */
- raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
-
- /* Sanity check */
- WARN_ON_ONCE(rcu_cblist_n_cbs(&rdp->nocb_bypass));
-
-
- return ret;
-}
-
-int rcu_nocb_cpu_deoffload(int cpu)
-{
- struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
- int ret = 0;
-
- mutex_lock(&rcu_state.barrier_mutex);
- cpus_read_lock();
- if (rcu_rdp_is_offloaded(rdp)) {
- if (cpu_online(cpu)) {
- ret = work_on_cpu(cpu, rcu_nocb_rdp_deoffload, rdp);
- if (!ret)
- cpumask_clear_cpu(cpu, rcu_nocb_mask);
- } else {
- pr_info("NOCB: Can't CB-deoffload an offline CPU\n");
- ret = -EINVAL;
- }
- }
- cpus_read_unlock();
- mutex_unlock(&rcu_state.barrier_mutex);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(rcu_nocb_cpu_deoffload);
-
-static long rcu_nocb_rdp_offload(void *arg)
-{
- struct rcu_data *rdp = arg;
- struct rcu_segcblist *cblist = &rdp->cblist;
- unsigned long flags;
- int ret;
-
- WARN_ON_ONCE(rdp->cpu != raw_smp_processor_id());
- /*
- * For now we only support re-offload, ie: the rdp must have been
- * offloaded on boot first.
- */
- if (!rdp->nocb_gp_rdp)
- return -EINVAL;
-
- pr_info("Offloading %d\n", rdp->cpu);
- /*
- * Can't use rcu_nocb_lock_irqsave() while we are in
- * SEGCBLIST_SOFTIRQ_ONLY mode.
- */
- raw_spin_lock_irqsave(&rdp->nocb_lock, flags);
-
- /*
- * We didn't take the nocb lock while working on the
- * rdp->cblist in SEGCBLIST_SOFTIRQ_ONLY mode.
- * Every modifications that have been done previously on
- * rdp->cblist must be visible remotely by the nocb kthreads
- * upon wake up after reading the cblist flags.
- *
- * The layout against nocb_lock enforces that ordering:
- *
- * __rcu_nocb_rdp_offload() nocb_cb_wait()/nocb_gp_wait()
- * ------------------------- ----------------------------
- * WRITE callbacks rcu_nocb_lock()
- * rcu_nocb_lock() READ flags
- * WRITE flags READ callbacks
- * rcu_nocb_unlock() rcu_nocb_unlock()
- */
- ret = rdp_offload_toggle(rdp, true, flags);
- swait_event_exclusive(rdp->nocb_state_wq,
- rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB) &&
- rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP));
-
- return ret;
-}
-
-int rcu_nocb_cpu_offload(int cpu)
-{
- struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
- int ret = 0;
-
- mutex_lock(&rcu_state.barrier_mutex);
- cpus_read_lock();
- if (!rcu_rdp_is_offloaded(rdp)) {
- if (cpu_online(cpu)) {
- ret = work_on_cpu(cpu, rcu_nocb_rdp_offload, rdp);
- if (!ret)
- cpumask_set_cpu(cpu, rcu_nocb_mask);
- } else {
- pr_info("NOCB: Can't CB-offload an offline CPU\n");
- ret = -EINVAL;
- }
- }
- cpus_read_unlock();
- mutex_unlock(&rcu_state.barrier_mutex);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(rcu_nocb_cpu_offload);
-
-void __init rcu_init_nohz(void)
-{
- int cpu;
- bool need_rcu_nocb_mask = false;
- struct rcu_data *rdp;
-
-#if defined(CONFIG_NO_HZ_FULL)
- if (tick_nohz_full_running && cpumask_weight(tick_nohz_full_mask))
- need_rcu_nocb_mask = true;
-#endif /* #if defined(CONFIG_NO_HZ_FULL) */
-
- if (!cpumask_available(rcu_nocb_mask) && need_rcu_nocb_mask) {
- if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
- pr_info("rcu_nocb_mask allocation failed, callback offloading disabled.\n");
- return;
- }
- }
- if (!cpumask_available(rcu_nocb_mask))
- return;
-
-#if defined(CONFIG_NO_HZ_FULL)
- if (tick_nohz_full_running)
- cpumask_or(rcu_nocb_mask, rcu_nocb_mask, tick_nohz_full_mask);
-#endif /* #if defined(CONFIG_NO_HZ_FULL) */
-
- if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
- pr_info("\tNote: kernel parameter 'rcu_nocbs=', 'nohz_full', or 'isolcpus=' contains nonexistent CPUs.\n");
- cpumask_and(rcu_nocb_mask, cpu_possible_mask,
- rcu_nocb_mask);
- }
- if (cpumask_empty(rcu_nocb_mask))
- pr_info("\tOffload RCU callbacks from CPUs: (none).\n");
- else
- pr_info("\tOffload RCU callbacks from CPUs: %*pbl.\n",
- cpumask_pr_args(rcu_nocb_mask));
- if (rcu_nocb_poll)
- pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
-
- for_each_cpu(cpu, rcu_nocb_mask) {
- rdp = per_cpu_ptr(&rcu_data, cpu);
- if (rcu_segcblist_empty(&rdp->cblist))
- rcu_segcblist_init(&rdp->cblist);
- rcu_segcblist_offload(&rdp->cblist, true);
- rcu_segcblist_set_flags(&rdp->cblist, SEGCBLIST_KTHREAD_CB);
- rcu_segcblist_set_flags(&rdp->cblist, SEGCBLIST_KTHREAD_GP);
- }
- rcu_organize_nocb_kthreads();
-}
-
-/* Initialize per-rcu_data variables for no-CBs CPUs. */
-static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
-{
- init_swait_queue_head(&rdp->nocb_cb_wq);
- init_swait_queue_head(&rdp->nocb_gp_wq);
- init_swait_queue_head(&rdp->nocb_state_wq);
- raw_spin_lock_init(&rdp->nocb_lock);
- raw_spin_lock_init(&rdp->nocb_bypass_lock);
- raw_spin_lock_init(&rdp->nocb_gp_lock);
- timer_setup(&rdp->nocb_timer, do_nocb_deferred_wakeup_timer, 0);
- rcu_cblist_init(&rdp->nocb_bypass);
-}
-
-/*
- * If the specified CPU is a no-CBs CPU that does not already have its
- * rcuo CB kthread, spawn it. Additionally, if the rcuo GP kthread
- * for this CPU's group has not yet been created, spawn it as well.
- */
-static void rcu_spawn_one_nocb_kthread(int cpu)
-{
- struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
- struct rcu_data *rdp_gp;
- struct task_struct *t;
-
- /*
- * If this isn't a no-CBs CPU or if it already has an rcuo kthread,
- * then nothing to do.
- */
- if (!rcu_is_nocb_cpu(cpu) || rdp->nocb_cb_kthread)
- return;
-
- /* If we didn't spawn the GP kthread first, reorganize! */
- rdp_gp = rdp->nocb_gp_rdp;
- if (!rdp_gp->nocb_gp_kthread) {
- t = kthread_run(rcu_nocb_gp_kthread, rdp_gp,
- "rcuog/%d", rdp_gp->cpu);
- if (WARN_ONCE(IS_ERR(t), "%s: Could not start rcuo GP kthread, OOM is now expected behavior\n", __func__))
- return;
- WRITE_ONCE(rdp_gp->nocb_gp_kthread, t);
- }
-
- /* Spawn the kthread for this CPU. */
- t = kthread_run(rcu_nocb_cb_kthread, rdp,
- "rcuo%c/%d", rcu_state.abbr, cpu);
- if (WARN_ONCE(IS_ERR(t), "%s: Could not start rcuo CB kthread, OOM is now expected behavior\n", __func__))
- return;
- WRITE_ONCE(rdp->nocb_cb_kthread, t);
- WRITE_ONCE(rdp->nocb_gp_kthread, rdp_gp->nocb_gp_kthread);
-}
-
-/*
- * If the specified CPU is a no-CBs CPU that does not already have its
- * rcuo kthread, spawn it.
- */
-static void rcu_spawn_cpu_nocb_kthread(int cpu)
-{
- if (rcu_scheduler_fully_active)
- rcu_spawn_one_nocb_kthread(cpu);
-}
-
-/*
- * Once the scheduler is running, spawn rcuo kthreads for all online
- * no-CBs CPUs. This assumes that the early_initcall()s happen before
- * non-boot CPUs come online -- if this changes, we will need to add
- * some mutual exclusion.
- */
-static void __init rcu_spawn_nocb_kthreads(void)
-{
- int cpu;
-
- for_each_online_cpu(cpu)
- rcu_spawn_cpu_nocb_kthread(cpu);
-}
-
-/* How many CB CPU IDs per GP kthread? Default of -1 for sqrt(nr_cpu_ids). */
-static int rcu_nocb_gp_stride = -1;
-module_param(rcu_nocb_gp_stride, int, 0444);
-
-/*
- * Initialize GP-CB relationships for all no-CBs CPU.
- */
-static void __init rcu_organize_nocb_kthreads(void)
-{
- int cpu;
- bool firsttime = true;
- bool gotnocbs = false;
- bool gotnocbscbs = true;
- int ls = rcu_nocb_gp_stride;
- int nl = 0; /* Next GP kthread. */
- struct rcu_data *rdp;
- struct rcu_data *rdp_gp = NULL; /* Suppress misguided gcc warn. */
- struct rcu_data *rdp_prev = NULL;
-
- if (!cpumask_available(rcu_nocb_mask))
- return;
- if (ls == -1) {
- ls = nr_cpu_ids / int_sqrt(nr_cpu_ids);
- rcu_nocb_gp_stride = ls;
- }
-
- /*
- * Each pass through this loop sets up one rcu_data structure.
- * Should the corresponding CPU come online in the future, then
- * we will spawn the needed set of rcu_nocb_kthread() kthreads.
- */
- for_each_cpu(cpu, rcu_nocb_mask) {
- rdp = per_cpu_ptr(&rcu_data, cpu);
- if (rdp->cpu >= nl) {
- /* New GP kthread, set up for CBs & next GP. */
- gotnocbs = true;
- nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls;
- rdp->nocb_gp_rdp = rdp;
- rdp_gp = rdp;
- if (dump_tree) {
- if (!firsttime)
- pr_cont("%s\n", gotnocbscbs
- ? "" : " (self only)");
- gotnocbscbs = false;
- firsttime = false;
- pr_alert("%s: No-CB GP kthread CPU %d:",
- __func__, cpu);
- }
- } else {
- /* Another CB kthread, link to previous GP kthread. */
- gotnocbscbs = true;
- rdp->nocb_gp_rdp = rdp_gp;
- rdp_prev->nocb_next_cb_rdp = rdp;
- if (dump_tree)
- pr_cont(" %d", cpu);
- }
- rdp_prev = rdp;
- }
- if (gotnocbs && dump_tree)
- pr_cont("%s\n", gotnocbscbs ? "" : " (self only)");
-}
-
-/*
- * Bind the current task to the offloaded CPUs. If there are no offloaded
- * CPUs, leave the task unbound. Splat if the bind attempt fails.
- */
-void rcu_bind_current_to_nocb(void)
-{
- if (cpumask_available(rcu_nocb_mask) && cpumask_weight(rcu_nocb_mask))
- WARN_ON(sched_setaffinity(current->pid, rcu_nocb_mask));
-}
-EXPORT_SYMBOL_GPL(rcu_bind_current_to_nocb);
-
-// The ->on_cpu field is available only in CONFIG_SMP=y, so...
-#ifdef CONFIG_SMP
-static char *show_rcu_should_be_on_cpu(struct task_struct *tsp)
-{
- return tsp && task_is_running(tsp) && !tsp->on_cpu ? "!" : "";
-}
-#else // #ifdef CONFIG_SMP
-static char *show_rcu_should_be_on_cpu(struct task_struct *tsp)
-{
- return "";
-}
-#endif // #else #ifdef CONFIG_SMP
-
-/*
- * Dump out nocb grace-period kthread state for the specified rcu_data
- * structure.
- */
-static void show_rcu_nocb_gp_state(struct rcu_data *rdp)
-{
- struct rcu_node *rnp = rdp->mynode;
-
- pr_info("nocb GP %d %c%c%c%c%c %c[%c%c] %c%c:%ld rnp %d:%d %lu %c CPU %d%s\n",
- rdp->cpu,
- "kK"[!!rdp->nocb_gp_kthread],
- "lL"[raw_spin_is_locked(&rdp->nocb_gp_lock)],
- "dD"[!!rdp->nocb_defer_wakeup],
- "tT"[timer_pending(&rdp->nocb_timer)],
- "sS"[!!rdp->nocb_gp_sleep],
- ".W"[swait_active(&rdp->nocb_gp_wq)],
- ".W"[swait_active(&rnp->nocb_gp_wq[0])],
- ".W"[swait_active(&rnp->nocb_gp_wq[1])],
- ".B"[!!rdp->nocb_gp_bypass],
- ".G"[!!rdp->nocb_gp_gp],
- (long)rdp->nocb_gp_seq,
- rnp->grplo, rnp->grphi, READ_ONCE(rdp->nocb_gp_loops),
- rdp->nocb_gp_kthread ? task_state_to_char(rdp->nocb_gp_kthread) : '.',
- rdp->nocb_cb_kthread ? (int)task_cpu(rdp->nocb_gp_kthread) : -1,
- show_rcu_should_be_on_cpu(rdp->nocb_cb_kthread));
-}
-
-/* Dump out nocb kthread state for the specified rcu_data structure. */
-static void show_rcu_nocb_state(struct rcu_data *rdp)
-{
- char bufw[20];
- char bufr[20];
- struct rcu_segcblist *rsclp = &rdp->cblist;
- bool waslocked;
- bool wassleep;
-
- if (rdp->nocb_gp_rdp == rdp)
- show_rcu_nocb_gp_state(rdp);
-
- sprintf(bufw, "%ld", rsclp->gp_seq[RCU_WAIT_TAIL]);
- sprintf(bufr, "%ld", rsclp->gp_seq[RCU_NEXT_READY_TAIL]);
- pr_info(" CB %d^%d->%d %c%c%c%c%c%c F%ld L%ld C%d %c%c%s%c%s%c%c q%ld %c CPU %d%s\n",
- rdp->cpu, rdp->nocb_gp_rdp->cpu,
- rdp->nocb_next_cb_rdp ? rdp->nocb_next_cb_rdp->cpu : -1,
- "kK"[!!rdp->nocb_cb_kthread],
- "bB"[raw_spin_is_locked(&rdp->nocb_bypass_lock)],
- "cC"[!!atomic_read(&rdp->nocb_lock_contended)],
- "lL"[raw_spin_is_locked(&rdp->nocb_lock)],
- "sS"[!!rdp->nocb_cb_sleep],
- ".W"[swait_active(&rdp->nocb_cb_wq)],
- jiffies - rdp->nocb_bypass_first,
- jiffies - rdp->nocb_nobypass_last,
- rdp->nocb_nobypass_count,
- ".D"[rcu_segcblist_ready_cbs(rsclp)],
- ".W"[!rcu_segcblist_segempty(rsclp, RCU_WAIT_TAIL)],
- rcu_segcblist_segempty(rsclp, RCU_WAIT_TAIL) ? "" : bufw,
- ".R"[!rcu_segcblist_segempty(rsclp, RCU_NEXT_READY_TAIL)],
- rcu_segcblist_segempty(rsclp, RCU_NEXT_READY_TAIL) ? "" : bufr,
- ".N"[!rcu_segcblist_segempty(rsclp, RCU_NEXT_TAIL)],
- ".B"[!!rcu_cblist_n_cbs(&rdp->nocb_bypass)],
- rcu_segcblist_n_cbs(&rdp->cblist),
- rdp->nocb_cb_kthread ? task_state_to_char(rdp->nocb_cb_kthread) : '.',
- rdp->nocb_cb_kthread ? (int)task_cpu(rdp->nocb_gp_kthread) : -1,
- show_rcu_should_be_on_cpu(rdp->nocb_cb_kthread));
-
- /* It is OK for GP kthreads to have GP state. */
- if (rdp->nocb_gp_rdp == rdp)
- return;
-
- waslocked = raw_spin_is_locked(&rdp->nocb_gp_lock);
- wassleep = swait_active(&rdp->nocb_gp_wq);
- if (!rdp->nocb_gp_sleep && !waslocked && !wassleep)
- return; /* Nothing untoward. */
-
- pr_info(" nocb GP activity on CB-only CPU!!! %c%c%c %c\n",
- "lL"[waslocked],
- "dD"[!!rdp->nocb_defer_wakeup],
- "sS"[!!rdp->nocb_gp_sleep],
- ".W"[wassleep]);
-}
-
-#else /* #ifdef CONFIG_RCU_NOCB_CPU */
-
-/* No ->nocb_lock to acquire. */
-static void rcu_nocb_lock(struct rcu_data *rdp)
-{
-}
-
-/* No ->nocb_lock to release. */
-static void rcu_nocb_unlock(struct rcu_data *rdp)
-{
-}
-
-/* No ->nocb_lock to release. */
-static void rcu_nocb_unlock_irqrestore(struct rcu_data *rdp,
- unsigned long flags)
-{
- local_irq_restore(flags);
-}
-
-/* Lockdep check that ->cblist may be safely accessed. */
-static void rcu_lockdep_assert_cblist_protected(struct rcu_data *rdp)
-{
- lockdep_assert_irqs_disabled();
-}
-
-static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq)
-{
-}
-
-static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp)
-{
- return NULL;
-}
-
-static void rcu_init_one_nocb(struct rcu_node *rnp)
-{
-}
-
-static bool rcu_nocb_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
- unsigned long j)
-{
- return true;
-}
-
-static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
- bool *was_alldone, unsigned long flags)
-{
- return false;
-}
-
-static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_empty,
- unsigned long flags)
-{
- WARN_ON_ONCE(1); /* Should be dead code! */
-}
-
-static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
-{
-}
-
-static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level)
-{
- return false;
-}
-
-static bool do_nocb_deferred_wakeup(struct rcu_data *rdp)
-{
- return false;
-}
-
-static void rcu_spawn_cpu_nocb_kthread(int cpu)
-{
-}
-
-static void __init rcu_spawn_nocb_kthreads(void)
-{
-}
-
-static void show_rcu_nocb_state(struct rcu_data *rdp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
-
/*
* Is this CPU a NO_HZ_FULL CPU that should ignore RCU so that the
* grace-period kthread will do force_quiescent_state() processing?
/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */
static void rcu_dynticks_task_trace_enter(void)
{
-#ifdef CONFIG_TASKS_RCU_TRACE
+#ifdef CONFIG_TASKS_TRACE_RCU
if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
current->trc_reader_special.b.need_mb = true;
-#endif /* #ifdef CONFIG_TASKS_RCU_TRACE */
+#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
}
/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */
static void rcu_dynticks_task_trace_exit(void)
{
-#ifdef CONFIG_TASKS_RCU_TRACE
+#ifdef CONFIG_TASKS_TRACE_RCU
if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
current->trc_reader_special.b.need_mb = false;
-#endif /* #ifdef CONFIG_TASKS_RCU_TRACE */
+#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
}
static atomic_t sched_core_count;
static struct cpumask sched_core_mask;
+static void sched_core_lock(int cpu, unsigned long *flags)
+{
+ const struct cpumask *smt_mask = cpu_smt_mask(cpu);
+ int t, i = 0;
+
+ local_irq_save(*flags);
+ for_each_cpu(t, smt_mask)
+ raw_spin_lock_nested(&cpu_rq(t)->__lock, i++);
+}
+
+static void sched_core_unlock(int cpu, unsigned long *flags)
+{
+ const struct cpumask *smt_mask = cpu_smt_mask(cpu);
+ int t;
+
+ for_each_cpu(t, smt_mask)
+ raw_spin_unlock(&cpu_rq(t)->__lock);
+ local_irq_restore(*flags);
+}
+
static void __sched_core_flip(bool enabled)
{
- int cpu, t, i;
+ unsigned long flags;
+ int cpu, t;
cpus_read_lock();
for_each_cpu(cpu, &sched_core_mask) {
const struct cpumask *smt_mask = cpu_smt_mask(cpu);
- i = 0;
- local_irq_disable();
- for_each_cpu(t, smt_mask) {
- /* supports up to SMT8 */
- raw_spin_lock_nested(&cpu_rq(t)->__lock, i++);
- }
+ sched_core_lock(cpu, &flags);
for_each_cpu(t, smt_mask)
cpu_rq(t)->core_enabled = enabled;
- for_each_cpu(t, smt_mask)
- raw_spin_unlock(&cpu_rq(t)->__lock);
- local_irq_enable();
+ sched_core_unlock(cpu, &flags);
cpumask_andnot(&sched_core_mask, &sched_core_mask, smt_mask);
}
{
int i, cpu = smp_processor_id(), default_cpu = -1;
struct sched_domain *sd;
+ const struct cpumask *hk_mask;
if (housekeeping_cpu(cpu, HK_FLAG_TIMER)) {
if (!idle_cpu(cpu))
default_cpu = cpu;
}
+ hk_mask = housekeeping_cpumask(HK_FLAG_TIMER);
+
rcu_read_lock();
for_each_domain(cpu, sd) {
- for_each_cpu_and(i, sched_domain_span(sd),
- housekeeping_cpumask(HK_FLAG_TIMER)) {
+ for_each_cpu_and(i, sched_domain_span(sd), hk_mask) {
if (cpu == i)
continue;
uclamp_rq_dec_id(rq, p, clamp_id);
}
+static inline void uclamp_rq_reinc_id(struct rq *rq, struct task_struct *p,
+ enum uclamp_id clamp_id)
+{
+ if (!p->uclamp[clamp_id].active)
+ return;
+
+ uclamp_rq_dec_id(rq, p, clamp_id);
+ uclamp_rq_inc_id(rq, p, clamp_id);
+
+ /*
+ * Make sure to clear the idle flag if we've transiently reached 0
+ * active tasks on rq.
+ */
+ if (clamp_id == UCLAMP_MAX && (rq->uclamp_flags & UCLAMP_FLAG_IDLE))
+ rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
+}
+
static inline void
uclamp_update_active(struct task_struct *p)
{
* affecting a valid clamp bucket, the next time it's enqueued,
* it will already see the updated clamp bucket value.
*/
- for_each_clamp_id(clamp_id) {
- if (p->uclamp[clamp_id].active) {
- uclamp_rq_dec_id(rq, p, clamp_id);
- uclamp_rq_inc_id(rq, p, clamp_id);
- }
- }
+ for_each_clamp_id(clamp_id)
+ uclamp_rq_reinc_id(rq, p, clamp_id);
task_rq_unlock(rq, p, &rf);
}
/* Non kernel threads are not allowed during either online or offline. */
if (!(p->flags & PF_KTHREAD))
- return cpu_active(cpu);
+ return cpu_active(cpu) && task_cpu_possible(cpu, p);
/* KTHREAD_IS_PER_CPU is always allowed. */
if (kthread_is_per_cpu(p))
__do_set_cpus_allowed(p, new_mask, 0);
}
+int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src,
+ int node)
+{
+ if (!src->user_cpus_ptr)
+ return 0;
+
+ dst->user_cpus_ptr = kmalloc_node(cpumask_size(), GFP_KERNEL, node);
+ if (!dst->user_cpus_ptr)
+ return -ENOMEM;
+
+ cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr);
+ return 0;
+}
+
+static inline struct cpumask *clear_user_cpus_ptr(struct task_struct *p)
+{
+ struct cpumask *user_mask = NULL;
+
+ swap(p->user_cpus_ptr, user_mask);
+
+ return user_mask;
+}
+
+void release_user_cpus_ptr(struct task_struct *p)
+{
+ kfree(clear_user_cpus_ptr(p));
+}
+
/*
* This function is wildly self concurrent; here be dragons.
*
}
/*
- * Change a given task's CPU affinity. Migrate the thread to a
- * proper CPU and schedule it away if the CPU it's executing on
- * is removed from the allowed bitmask.
- *
- * NOTE: the caller must have a valid reference to the task, the
- * task must not exit() & deallocate itself prematurely. The
- * call is not atomic; no spinlocks may be held.
+ * Called with both p->pi_lock and rq->lock held; drops both before returning.
*/
-static int __set_cpus_allowed_ptr(struct task_struct *p,
- const struct cpumask *new_mask,
- u32 flags)
+static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
+ const struct cpumask *new_mask,
+ u32 flags,
+ struct rq *rq,
+ struct rq_flags *rf)
+ __releases(rq->lock)
+ __releases(p->pi_lock)
{
+ const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p);
const struct cpumask *cpu_valid_mask = cpu_active_mask;
+ bool kthread = p->flags & PF_KTHREAD;
+ struct cpumask *user_mask = NULL;
unsigned int dest_cpu;
- struct rq_flags rf;
- struct rq *rq;
int ret = 0;
- rq = task_rq_lock(p, &rf);
update_rq_clock(rq);
- if (p->flags & PF_KTHREAD || is_migration_disabled(p)) {
+ if (kthread || is_migration_disabled(p)) {
/*
* Kernel threads are allowed on online && !active CPUs,
* however, during cpu-hot-unplug, even these might get pushed
cpu_valid_mask = cpu_online_mask;
}
+ if (!kthread && !cpumask_subset(new_mask, cpu_allowed_mask)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
/*
* Must re-check here, to close a race against __kthread_bind(),
* sched_setaffinity() is not guaranteed to observe the flag.
__do_set_cpus_allowed(p, new_mask, flags);
- return affine_move_task(rq, p, &rf, dest_cpu, flags);
+ if (flags & SCA_USER)
+ user_mask = clear_user_cpus_ptr(p);
+
+ ret = affine_move_task(rq, p, rf, dest_cpu, flags);
+
+ kfree(user_mask);
+
+ return ret;
out:
- task_rq_unlock(rq, p, &rf);
+ task_rq_unlock(rq, p, rf);
return ret;
}
+/*
+ * Change a given task's CPU affinity. Migrate the thread to a
+ * proper CPU and schedule it away if the CPU it's executing on
+ * is removed from the allowed bitmask.
+ *
+ * NOTE: the caller must have a valid reference to the task, the
+ * task must not exit() & deallocate itself prematurely. The
+ * call is not atomic; no spinlocks may be held.
+ */
+static int __set_cpus_allowed_ptr(struct task_struct *p,
+ const struct cpumask *new_mask, u32 flags)
+{
+ struct rq_flags rf;
+ struct rq *rq;
+
+ rq = task_rq_lock(p, &rf);
+ return __set_cpus_allowed_ptr_locked(p, new_mask, flags, rq, &rf);
+}
+
int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
{
return __set_cpus_allowed_ptr(p, new_mask, 0);
}
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
+/*
+ * Change a given task's CPU affinity to the intersection of its current
+ * affinity mask and @subset_mask, writing the resulting mask to @new_mask
+ * and pointing @p->user_cpus_ptr to a copy of the old mask.
+ * If the resulting mask is empty, leave the affinity unchanged and return
+ * -EINVAL.
+ */
+static int restrict_cpus_allowed_ptr(struct task_struct *p,
+ struct cpumask *new_mask,
+ const struct cpumask *subset_mask)
+{
+ struct cpumask *user_mask = NULL;
+ struct rq_flags rf;
+ struct rq *rq;
+ int err;
+
+ if (!p->user_cpus_ptr) {
+ user_mask = kmalloc(cpumask_size(), GFP_KERNEL);
+ if (!user_mask)
+ return -ENOMEM;
+ }
+
+ rq = task_rq_lock(p, &rf);
+
+ /*
+ * Forcefully restricting the affinity of a deadline task is
+ * likely to cause problems, so fail and noisily override the
+ * mask entirely.
+ */
+ if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
+ err = -EPERM;
+ goto err_unlock;
+ }
+
+ if (!cpumask_and(new_mask, &p->cpus_mask, subset_mask)) {
+ err = -EINVAL;
+ goto err_unlock;
+ }
+
+ /*
+ * We're about to butcher the task affinity, so keep track of what
+ * the user asked for in case we're able to restore it later on.
+ */
+ if (user_mask) {
+ cpumask_copy(user_mask, p->cpus_ptr);
+ p->user_cpus_ptr = user_mask;
+ }
+
+ return __set_cpus_allowed_ptr_locked(p, new_mask, 0, rq, &rf);
+
+err_unlock:
+ task_rq_unlock(rq, p, &rf);
+ kfree(user_mask);
+ return err;
+}
+
+/*
+ * Restrict the CPU affinity of task @p so that it is a subset of
+ * task_cpu_possible_mask() and point @p->user_cpu_ptr to a copy of the
+ * old affinity mask. If the resulting mask is empty, we warn and walk
+ * up the cpuset hierarchy until we find a suitable mask.
+ */
+void force_compatible_cpus_allowed_ptr(struct task_struct *p)
+{
+ cpumask_var_t new_mask;
+ const struct cpumask *override_mask = task_cpu_possible_mask(p);
+
+ alloc_cpumask_var(&new_mask, GFP_KERNEL);
+
+ /*
+ * __migrate_task() can fail silently in the face of concurrent
+ * offlining of the chosen destination CPU, so take the hotplug
+ * lock to ensure that the migration succeeds.
+ */
+ cpus_read_lock();
+ if (!cpumask_available(new_mask))
+ goto out_set_mask;
+
+ if (!restrict_cpus_allowed_ptr(p, new_mask, override_mask))
+ goto out_free_mask;
+
+ /*
+ * We failed to find a valid subset of the affinity mask for the
+ * task, so override it based on its cpuset hierarchy.
+ */
+ cpuset_cpus_allowed(p, new_mask);
+ override_mask = new_mask;
+
+out_set_mask:
+ if (printk_ratelimit()) {
+ printk_deferred("Overriding affinity for process %d (%s) to CPUs %*pbl\n",
+ task_pid_nr(p), p->comm,
+ cpumask_pr_args(override_mask));
+ }
+
+ WARN_ON(set_cpus_allowed_ptr(p, override_mask));
+out_free_mask:
+ cpus_read_unlock();
+ free_cpumask_var(new_mask);
+}
+
+static int
+__sched_setaffinity(struct task_struct *p, const struct cpumask *mask);
+
+/*
+ * Restore the affinity of a task @p which was previously restricted by a
+ * call to force_compatible_cpus_allowed_ptr(). This will clear (and free)
+ * @p->user_cpus_ptr.
+ *
+ * It is the caller's responsibility to serialise this with any calls to
+ * force_compatible_cpus_allowed_ptr(@p).
+ */
+void relax_compatible_cpus_allowed_ptr(struct task_struct *p)
+{
+ struct cpumask *user_mask = p->user_cpus_ptr;
+ unsigned long flags;
+
+ /*
+ * Try to restore the old affinity mask. If this fails, then
+ * we free the mask explicitly to avoid it being inherited across
+ * a subsequent fork().
+ */
+ if (!user_mask || !__sched_setaffinity(p, user_mask))
+ return;
+
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
+ user_mask = clear_user_cpus_ptr(p);
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+ kfree(user_mask);
+}
+
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
#ifdef CONFIG_SCHED_DEBUG
/* Look for allowed, online CPU in same node. */
for_each_cpu(dest_cpu, nodemask) {
- if (!cpu_active(dest_cpu))
- continue;
- if (cpumask_test_cpu(dest_cpu, p->cpus_ptr))
+ if (is_cpu_allowed(p, dest_cpu))
return dest_cpu;
}
}
/* No more Mr. Nice Guy. */
switch (state) {
case cpuset:
- if (IS_ENABLED(CONFIG_CPUSETS)) {
- cpuset_cpus_allowed_fallback(p);
+ if (cpuset_cpus_allowed_fallback(p)) {
state = possible;
break;
}
*
* More yuck to audit.
*/
- do_set_cpus_allowed(p, cpu_possible_mask);
+ do_set_cpus_allowed(p, task_cpu_possible_mask(p));
state = fail;
break;
-
case fail:
BUG();
break;
rq_unlock(rq, &rf);
}
+ /*
+ * Invoked from try_to_wake_up() to check whether the task can be woken up.
+ *
+ * The caller holds p::pi_lock if p != current or has preemption
+ * disabled when p == current.
+ *
+ * The rules of PREEMPT_RT saved_state:
+ *
+ * The related locking code always holds p::pi_lock when updating
+ * p::saved_state, which means the code is fully serialized in both cases.
+ *
+ * The lock wait and lock wakeups happen via TASK_RTLOCK_WAIT. No other
+ * bits set. This allows to distinguish all wakeup scenarios.
+ */
+ static __always_inline
+ bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success)
+ {
+ if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)) {
+ WARN_ON_ONCE((state & TASK_RTLOCK_WAIT) &&
+ state != TASK_RTLOCK_WAIT);
+ }
+
+ if (READ_ONCE(p->__state) & state) {
+ *success = 1;
+ return true;
+ }
+
+ #ifdef CONFIG_PREEMPT_RT
+ /*
+ * Saved state preserves the task state across blocking on
+ * an RT lock. If the state matches, set p::saved_state to
+ * TASK_RUNNING, but do not wake the task because it waits
+ * for a lock wakeup. Also indicate success because from
+ * the regular waker's point of view this has succeeded.
+ *
+ * After acquiring the lock the task will restore p::__state
+ * from p::saved_state which ensures that the regular
+ * wakeup is not lost. The restore will also set
+ * p::saved_state to TASK_RUNNING so any further tests will
+ * not result in false positives vs. @success
+ */
+ if (p->saved_state & state) {
+ p->saved_state = TASK_RUNNING;
+ *success = 1;
+ }
+ #endif
+ return false;
+ }
+
/*
* Notes on Program-Order guarantees on SMP systems.
*
* - we're serialized against set_special_state() by virtue of
* it disabling IRQs (this allows not taking ->pi_lock).
*/
- if (!(READ_ONCE(p->__state) & state))
+ if (!ttwu_state_match(p, state, &success))
goto out;
- success = 1;
trace_sched_waking(p);
WRITE_ONCE(p->__state, TASK_RUNNING);
trace_sched_wakeup(p);
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
smp_mb__after_spinlock();
- if (!(READ_ONCE(p->__state) & state))
+ if (!ttwu_state_match(p, state, &success))
goto unlock;
trace_sched_waking(p);
- /* We're going to change ->state: */
- success = 1;
-
/*
* Ensure we load p->on_rq _after_ p->state, otherwise it would
* be possible to, falsely, observe p->on_rq == 0 and get stuck
if (p->core_occupation > dst->idle->core_occupation)
goto next;
- p->on_rq = TASK_ON_RQ_MIGRATING;
deactivate_task(src, p, 0);
set_task_cpu(p, this);
activate_task(dst, p, 0);
- p->on_rq = TASK_ON_RQ_QUEUED;
resched_curr(dst);
queue_balance_callback(rq, &per_cpu(core_balance_head, rq->cpu), sched_core_balance);
}
-static inline void sched_core_cpu_starting(unsigned int cpu)
+static void sched_core_cpu_starting(unsigned int cpu)
{
const struct cpumask *smt_mask = cpu_smt_mask(cpu);
- struct rq *rq, *core_rq = NULL;
- int i;
+ struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
+ unsigned long flags;
+ int t;
+
+ sched_core_lock(cpu, &flags);
- core_rq = cpu_rq(cpu)->core;
+ WARN_ON_ONCE(rq->core != rq);
+
+ /* if we're the first, we'll be our own leader */
+ if (cpumask_weight(smt_mask) == 1)
+ goto unlock;
- if (!core_rq) {
- for_each_cpu(i, smt_mask) {
- rq = cpu_rq(i);
- if (rq->core && rq->core == rq)
- core_rq = rq;
+ /* find the leader */
+ for_each_cpu(t, smt_mask) {
+ if (t == cpu)
+ continue;
+ rq = cpu_rq(t);
+ if (rq->core == rq) {
+ core_rq = rq;
+ break;
}
+ }
- if (!core_rq)
- core_rq = cpu_rq(cpu);
+ if (WARN_ON_ONCE(!core_rq)) /* whoopsie */
+ goto unlock;
- for_each_cpu(i, smt_mask) {
- rq = cpu_rq(i);
+ /* install and validate core_rq */
+ for_each_cpu(t, smt_mask) {
+ rq = cpu_rq(t);
- WARN_ON_ONCE(rq->core && rq->core != core_rq);
+ if (t == cpu)
rq->core = core_rq;
- }
+
+ WARN_ON_ONCE(rq->core != core_rq);
}
+
+unlock:
+ sched_core_unlock(cpu, &flags);
}
+
+static void sched_core_cpu_deactivate(unsigned int cpu)
+{
+ const struct cpumask *smt_mask = cpu_smt_mask(cpu);
+ struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
+ unsigned long flags;
+ int t;
+
+ sched_core_lock(cpu, &flags);
+
+ /* if we're the last man standing, nothing to do */
+ if (cpumask_weight(smt_mask) == 1) {
+ WARN_ON_ONCE(rq->core != rq);
+ goto unlock;
+ }
+
+ /* if we're not the leader, nothing to do */
+ if (rq->core != rq)
+ goto unlock;
+
+ /* find a new leader */
+ for_each_cpu(t, smt_mask) {
+ if (t == cpu)
+ continue;
+ core_rq = cpu_rq(t);
+ break;
+ }
+
+ if (WARN_ON_ONCE(!core_rq)) /* impossible */
+ goto unlock;
+
+ /* copy the shared state to the new leader */
+ core_rq->core_task_seq = rq->core_task_seq;
+ core_rq->core_pick_seq = rq->core_pick_seq;
+ core_rq->core_cookie = rq->core_cookie;
+ core_rq->core_forceidle = rq->core_forceidle;
+ core_rq->core_forceidle_seq = rq->core_forceidle_seq;
+
+ /* install new leader */
+ for_each_cpu(t, smt_mask) {
+ rq = cpu_rq(t);
+ rq->core = core_rq;
+ }
+
+unlock:
+ sched_core_unlock(cpu, &flags);
+}
+
+static inline void sched_core_cpu_dying(unsigned int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+
+ if (rq->core != rq)
+ rq->core = rq;
+}
+
#else /* !CONFIG_SCHED_CORE */
static inline void sched_core_cpu_starting(unsigned int cpu) {}
+static inline void sched_core_cpu_deactivate(unsigned int cpu) {}
+static inline void sched_core_cpu_dying(unsigned int cpu) {}
static struct task_struct *
pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
#endif /* CONFIG_SCHED_CORE */
+ /*
+ * Constants for the sched_mode argument of __schedule().
+ *
+ * The mode argument allows RT enabled kernels to differentiate a
+ * preemption from blocking on an 'sleeping' spin/rwlock. Note that
+ * SM_MASK_PREEMPT for !RT has all bits set, which allows the compiler to
+ * optimize the AND operation out and just check for zero.
+ */
+ #define SM_NONE 0x0
+ #define SM_PREEMPT 0x1
+ #define SM_RTLOCK_WAIT 0x2
+
+ #ifndef CONFIG_PREEMPT_RT
+ # define SM_MASK_PREEMPT (~0U)
+ #else
+ # define SM_MASK_PREEMPT SM_PREEMPT
+ #endif
+
/*
* __schedule() is the main scheduler function.
*
*
* WARNING: must be called with preemption disabled!
*/
- static void __sched notrace __schedule(bool preempt)
+ static void __sched notrace __schedule(unsigned int sched_mode)
{
struct task_struct *prev, *next;
unsigned long *switch_count;
rq = cpu_rq(cpu);
prev = rq->curr;
- schedule_debug(prev, preempt);
+ schedule_debug(prev, !!sched_mode);
if (sched_feat(HRTICK) || sched_feat(HRTICK_DL))
hrtick_clear(rq);
local_irq_disable();
- rcu_note_context_switch(preempt);
+ rcu_note_context_switch(!!sched_mode);
/*
* Make sure that signal_pending_state()->signal_pending() below
* - ptrace_{,un}freeze_traced() can change ->state underneath us.
*/
prev_state = READ_ONCE(prev->__state);
- if (!preempt && prev_state) {
+ if (!(sched_mode & SM_MASK_PREEMPT) && prev_state) {
if (signal_pending_state(prev_state, prev)) {
WRITE_ONCE(prev->__state, TASK_RUNNING);
} else {
migrate_disable_switch(rq, prev);
psi_sched_switch(prev, next, !task_on_rq_queued(prev));
- trace_sched_switch(preempt, prev, next);
+ trace_sched_switch(sched_mode & SM_MASK_PREEMPT, prev, next);
/* Also unlocks the rq: */
rq = context_switch(rq, prev, next, &rf);
/* Tell freezer to ignore us: */
current->flags |= PF_NOFREEZE;
- __schedule(false);
+ __schedule(SM_NONE);
BUG();
/* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
sched_submit_work(tsk);
do {
preempt_disable();
- __schedule(false);
+ __schedule(SM_NONE);
sched_preempt_enable_no_resched();
} while (need_resched());
sched_update_worker(tsk);
*/
WARN_ON_ONCE(current->__state);
do {
- __schedule(false);
+ __schedule(SM_NONE);
} while (need_resched());
}
preempt_disable();
}
+ #ifdef CONFIG_PREEMPT_RT
+ void __sched notrace schedule_rtlock(void)
+ {
+ do {
+ preempt_disable();
+ __schedule(SM_RTLOCK_WAIT);
+ sched_preempt_enable_no_resched();
+ } while (need_resched());
+ }
+ NOKPROBE_SYMBOL(schedule_rtlock);
+ #endif
+
static void __sched notrace preempt_schedule_common(void)
{
do {
*/
preempt_disable_notrace();
preempt_latency_start(1);
- __schedule(true);
+ __schedule(SM_PREEMPT);
preempt_latency_stop(1);
preempt_enable_no_resched_notrace();
* an infinite recursion.
*/
prev_ctx = exception_enter();
- __schedule(true);
+ __schedule(SM_PREEMPT);
exception_exit(prev_ctx);
preempt_latency_stop(1);
do {
preempt_disable();
local_irq_enable();
- __schedule(true);
+ __schedule(SM_PREEMPT);
local_irq_disable();
sched_preempt_enable_no_resched();
} while (need_resched());
return -E2BIG;
}
+static void get_params(struct task_struct *p, struct sched_attr *attr)
+{
+ if (task_has_dl_policy(p))
+ __getparam_dl(p, attr);
+ else if (task_has_rt_policy(p))
+ attr->sched_priority = p->rt_priority;
+ else
+ attr->sched_nice = task_nice(p);
+}
+
/**
* sys_sched_setscheduler - set/change the scheduler policy and RT priority
* @pid: the pid in question.
rcu_read_unlock();
if (likely(p)) {
+ if (attr.sched_flags & SCHED_FLAG_KEEP_PARAMS)
+ get_params(p, &attr);
retval = sched_setattr(p, &attr);
put_task_struct(p);
}
kattr.sched_policy = p->policy;
if (p->sched_reset_on_fork)
kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
- if (task_has_dl_policy(p))
- __getparam_dl(p, &kattr);
- else if (task_has_rt_policy(p))
- kattr.sched_priority = p->rt_priority;
- else
- kattr.sched_nice = task_nice(p);
+ get_params(p, &kattr);
+ kattr.sched_flags &= SCHED_FLAG_ALL;
#ifdef CONFIG_UCLAMP_TASK
/*
return retval;
}
-long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+#ifdef CONFIG_SMP
+int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
{
+ int ret = 0;
+
+ /*
+ * If the task isn't a deadline task or admission control is
+ * disabled then we don't care about affinity changes.
+ */
+ if (!task_has_dl_policy(p) || !dl_bandwidth_enabled())
+ return 0;
+
+ /*
+ * Since bandwidth control happens on root_domain basis,
+ * if admission test is enabled, we only admit -deadline
+ * tasks allowed to run on all the CPUs in the task's
+ * root_domain.
+ */
+ rcu_read_lock();
+ if (!cpumask_subset(task_rq(p)->rd->span, mask))
+ ret = -EBUSY;
+ rcu_read_unlock();
+ return ret;
+}
+#endif
+
+static int
+__sched_setaffinity(struct task_struct *p, const struct cpumask *mask)
+{
+ int retval;
cpumask_var_t cpus_allowed, new_mask;
+
+ if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL))
+ return -ENOMEM;
+
+ if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
+ retval = -ENOMEM;
+ goto out_free_cpus_allowed;
+ }
+
+ cpuset_cpus_allowed(p, cpus_allowed);
+ cpumask_and(new_mask, mask, cpus_allowed);
+
+ retval = dl_task_check_affinity(p, new_mask);
+ if (retval)
+ goto out_free_new_mask;
+again:
+ retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK | SCA_USER);
+ if (retval)
+ goto out_free_new_mask;
+
+ cpuset_cpus_allowed(p, cpus_allowed);
+ if (!cpumask_subset(new_mask, cpus_allowed)) {
+ /*
+ * We must have raced with a concurrent cpuset update.
+ * Just reset the cpumask to the cpuset's cpus_allowed.
+ */
+ cpumask_copy(new_mask, cpus_allowed);
+ goto again;
+ }
+
+out_free_new_mask:
+ free_cpumask_var(new_mask);
+out_free_cpus_allowed:
+ free_cpumask_var(cpus_allowed);
+ return retval;
+}
+
+long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+{
struct task_struct *p;
int retval;
retval = -EINVAL;
goto out_put_task;
}
- if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
- retval = -ENOMEM;
- goto out_put_task;
- }
- if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
- retval = -ENOMEM;
- goto out_free_cpus_allowed;
- }
- retval = -EPERM;
+
if (!check_same_owner(p)) {
rcu_read_lock();
if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
rcu_read_unlock();
- goto out_free_new_mask;
+ retval = -EPERM;
+ goto out_put_task;
}
rcu_read_unlock();
}
retval = security_task_setscheduler(p);
if (retval)
- goto out_free_new_mask;
-
-
- cpuset_cpus_allowed(p, cpus_allowed);
- cpumask_and(new_mask, in_mask, cpus_allowed);
-
- /*
- * Since bandwidth control happens on root_domain basis,
- * if admission test is enabled, we only admit -deadline
- * tasks allowed to run on all the CPUs in the task's
- * root_domain.
- */
-#ifdef CONFIG_SMP
- if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
- rcu_read_lock();
- if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
- retval = -EBUSY;
- rcu_read_unlock();
- goto out_free_new_mask;
- }
- rcu_read_unlock();
- }
-#endif
-again:
- retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK);
+ goto out_put_task;
- if (!retval) {
- cpuset_cpus_allowed(p, cpus_allowed);
- if (!cpumask_subset(new_mask, cpus_allowed)) {
- /*
- * We must have raced with a concurrent cpuset
- * update. Just reset the cpus_allowed to the
- * cpuset's cpus_allowed
- */
- cpumask_copy(new_mask, cpus_allowed);
- goto again;
- }
- }
-out_free_new_mask:
- free_cpumask_var(new_mask);
-out_free_cpus_allowed:
- free_cpumask_var(cpus_allowed);
+ retval = __sched_setaffinity(p, in_mask);
out_put_task:
put_task_struct(p);
return retval;
preempt_schedule_common();
return 1;
}
+ /*
+ * In preemptible kernels, ->rcu_read_lock_nesting tells the tick
+ * whether the current CPU is in an RCU read-side critical section,
+ * so the tick can report quiescent states even for CPUs looping
+ * in kernel context. In contrast, in non-preemptible kernels,
+ * RCU readers leave no in-memory hints, which means that CPU-bound
+ * processes executing in kernel context might never report an
+ * RCU quiescent state. Therefore, the following code causes
+ * cond_resched() to report a quiescent state, but only when RCU
+ * is in urgent need of one.
+ */
#ifndef CONFIG_PREEMPT_RCU
rcu_all_qs();
#endif
*/
if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
static_branch_dec_cpuslocked(&sched_smt_present);
+
+ sched_core_cpu_deactivate(cpu);
#endif
if (!sched_smp_initialized)
calc_load_migrate(rq);
update_max_interval();
hrtick_clear(rq);
+ sched_core_cpu_dying(cpu);
return 0;
}
#endif
atomic_set(&rq->nr_iowait, 0);
#ifdef CONFIG_SCHED_CORE
- rq->core = NULL;
+ rq->core = rq;
rq->core_pick = NULL;
rq->core_enabled = 0;
rq->core_tree = RB_ROOT;
* Prevent race between setting of cfs_rq->runtime_enabled and
* unthrottle_offline_cfs_rqs().
*/
- get_online_cpus();
+ cpus_read_lock();
mutex_lock(&cfs_constraints_mutex);
ret = __cfs_schedulable(tg, period, quota);
if (ret)
cfs_bandwidth_usage_dec();
out_unlock:
mutex_unlock(&cfs_constraints_mutex);
- put_online_cpus();
+ cpus_read_unlock();
return ret;
}
}
#endif /* CONFIG_RT_GROUP_SCHED */
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static s64 cpu_idle_read_s64(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return css_tg(css)->idle;
+}
+
+static int cpu_idle_write_s64(struct cgroup_subsys_state *css,
+ struct cftype *cft, s64 idle)
+{
+ return sched_group_set_idle(css_tg(css), idle);
+}
+#endif
+
static struct cftype cpu_legacy_files[] = {
#ifdef CONFIG_FAIR_GROUP_SCHED
{
.read_u64 = cpu_shares_read_u64,
.write_u64 = cpu_shares_write_u64,
},
+ {
+ .name = "idle",
+ .read_s64 = cpu_idle_read_s64,
+ .write_s64 = cpu_idle_write_s64,
+ },
#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
.read_s64 = cpu_weight_nice_read_s64,
.write_s64 = cpu_weight_nice_write_s64,
},
+ {
+ .name = "idle",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_s64 = cpu_idle_read_s64,
+ .write_s64 = cpu_idle_write_s64,
+ },
#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
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