static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
.dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
-#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
- .dynticks_idle_nesting = DYNTICK_TASK_NEST_VALUE,
- .dynticks_idle = ATOMIC_INIT(1),
-#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
};
/*
static bool rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
struct rcu_data *rdp);
-static void force_qs_rnp(struct rcu_state *rsp,
- int (*f)(struct rcu_data *rsp, bool *isidle,
- unsigned long *maxj),
- bool *isidle, unsigned long *maxj);
+static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *rsp));
static void force_quiescent_state(struct rcu_state *rsp);
static int rcu_pending(void);
local_irq_save(flags);
rcu_eqs_enter(false);
- rcu_sysidle_enter(0);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_enter);
trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nesting, rdtp->dynticks_nesting - 1);
rdtp->dynticks_nesting--;
}
- rcu_sysidle_enter(1);
}
/*
local_irq_save(flags);
rcu_eqs_exit(false);
- rcu_sysidle_exit(0);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_exit);
trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting);
else
rcu_eqs_exit_common(oldval, true);
- rcu_sysidle_exit(1);
}
/*
* credit them with an implicit quiescent state. Return 1 if this CPU
* is in dynticks idle mode, which is an extended quiescent state.
*/
-static int dyntick_save_progress_counter(struct rcu_data *rdp,
- bool *isidle, unsigned long *maxj)
+static int dyntick_save_progress_counter(struct rcu_data *rdp)
{
rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks);
- rcu_sysidle_check_cpu(rdp, isidle, maxj);
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
* idle state since the last call to dyntick_save_progress_counter()
* for this same CPU, or by virtue of having been offline.
*/
-static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
- bool *isidle, unsigned long *maxj)
+static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
{
unsigned long jtsq;
bool *rnhqp;
*/
static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time)
{
- bool isidle = false;
- unsigned long maxj;
struct rcu_node *rnp = rcu_get_root(rsp);
WRITE_ONCE(rsp->gp_activity, jiffies);
rsp->n_force_qs++;
if (first_time) {
/* Collect dyntick-idle snapshots. */
- if (is_sysidle_rcu_state(rsp)) {
- isidle = true;
- maxj = jiffies - ULONG_MAX / 4;
- }
- force_qs_rnp(rsp, dyntick_save_progress_counter,
- &isidle, &maxj);
- rcu_sysidle_report_gp(rsp, isidle, maxj);
+ force_qs_rnp(rsp, dyntick_save_progress_counter);
} else {
/* Handle dyntick-idle and offline CPUs. */
- isidle = true;
- force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
+ force_qs_rnp(rsp, rcu_implicit_dynticks_qs);
}
/* Clear flag to prevent immediate re-entry. */
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
*
* The caller must have suppressed start of new grace periods.
*/
-static void force_qs_rnp(struct rcu_state *rsp,
- int (*f)(struct rcu_data *rsp, bool *isidle,
- unsigned long *maxj),
- bool *isidle, unsigned long *maxj)
+static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *rsp))
{
int cpu;
unsigned long flags;
for_each_leaf_node_possible_cpu(rnp, cpu) {
unsigned long bit = leaf_node_cpu_bit(rnp, cpu);
if ((rnp->qsmask & bit) != 0) {
- if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
+ if (f(per_cpu_ptr(rsp->rda, cpu)))
mask |= bit;
}
}
!init_nocb_callback_list(rdp))
rcu_segcblist_init(&rdp->cblist); /* Re-enable callbacks. */
rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
- rcu_sysidle_init_percpu_data(rdp->dynticks);
rcu_dynticks_eqs_online();
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
#endif /* #ifdef CONFIG_NO_HZ_FULL */
}
-
-#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
-
-static int full_sysidle_state; /* Current system-idle state. */
-#define RCU_SYSIDLE_NOT 0 /* Some CPU is not idle. */
-#define RCU_SYSIDLE_SHORT 1 /* All CPUs idle for brief period. */
-#define RCU_SYSIDLE_LONG 2 /* All CPUs idle for long enough. */
-#define RCU_SYSIDLE_FULL 3 /* All CPUs idle, ready for sysidle. */
-#define RCU_SYSIDLE_FULL_NOTED 4 /* Actually entered sysidle state. */
-
-/*
- * Invoked to note exit from irq or task transition to idle. Note that
- * usermode execution does -not- count as idle here! After all, we want
- * to detect full-system idle states, not RCU quiescent states and grace
- * periods. The caller must have disabled interrupts.
- */
-static void rcu_sysidle_enter(int irq)
-{
- unsigned long j;
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
-
- RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sysidle_enter() invoked with irqs enabled!!!");
-
- /* If there are no nohz_full= CPUs, no need to track this. */
- if (!tick_nohz_full_enabled())
- return;
-
- /* Adjust nesting, check for fully idle. */
- if (irq) {
- rdtp->dynticks_idle_nesting--;
- WARN_ON_ONCE(rdtp->dynticks_idle_nesting < 0);
- if (rdtp->dynticks_idle_nesting != 0)
- return; /* Still not fully idle. */
- } else {
- if ((rdtp->dynticks_idle_nesting & DYNTICK_TASK_NEST_MASK) ==
- DYNTICK_TASK_NEST_VALUE) {
- rdtp->dynticks_idle_nesting = 0;
- } else {
- rdtp->dynticks_idle_nesting -= DYNTICK_TASK_NEST_VALUE;
- WARN_ON_ONCE(rdtp->dynticks_idle_nesting < 0);
- return; /* Still not fully idle. */
- }
- }
-
- /* Record start of fully idle period. */
- j = jiffies;
- WRITE_ONCE(rdtp->dynticks_idle_jiffies, j);
- smp_mb__before_atomic();
- atomic_inc(&rdtp->dynticks_idle);
- smp_mb__after_atomic();
- WARN_ON_ONCE(atomic_read(&rdtp->dynticks_idle) & 0x1);
-}
-
-/*
- * Unconditionally force exit from full system-idle state. This is
- * invoked when a normal CPU exits idle, but must be called separately
- * for the timekeeping CPU (tick_do_timer_cpu). The reason for this
- * is that the timekeeping CPU is permitted to take scheduling-clock
- * interrupts while the system is in system-idle state, and of course
- * rcu_sysidle_exit() has no way of distinguishing a scheduling-clock
- * interrupt from any other type of interrupt.
- */
-void rcu_sysidle_force_exit(void)
-{
- int oldstate = READ_ONCE(full_sysidle_state);
- int newoldstate;
-
- /*
- * Each pass through the following loop attempts to exit full
- * system-idle state. If contention proves to be a problem,
- * a trylock-based contention tree could be used here.
- */
- while (oldstate > RCU_SYSIDLE_SHORT) {
- newoldstate = cmpxchg(&full_sysidle_state,
- oldstate, RCU_SYSIDLE_NOT);
- if (oldstate == newoldstate &&
- oldstate == RCU_SYSIDLE_FULL_NOTED) {
- rcu_kick_nohz_cpu(tick_do_timer_cpu);
- return; /* We cleared it, done! */
- }
- oldstate = newoldstate;
- }
- smp_mb(); /* Order initial oldstate fetch vs. later non-idle work. */
-}
-
-/*
- * Invoked to note entry to irq or task transition from idle. Note that
- * usermode execution does -not- count as idle here! The caller must
- * have disabled interrupts.
- */
-static void rcu_sysidle_exit(int irq)
-{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
-
- RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sysidle_exit() invoked with irqs enabled!!!");
-
- /* If there are no nohz_full= CPUs, no need to track this. */
- if (!tick_nohz_full_enabled())
- return;
-
- /* Adjust nesting, check for already non-idle. */
- if (irq) {
- rdtp->dynticks_idle_nesting++;
- WARN_ON_ONCE(rdtp->dynticks_idle_nesting <= 0);
- if (rdtp->dynticks_idle_nesting != 1)
- return; /* Already non-idle. */
- } else {
- /*
- * Allow for irq misnesting. Yes, it really is possible
- * to enter an irq handler then never leave it, and maybe
- * also vice versa. Handle both possibilities.
- */
- if (rdtp->dynticks_idle_nesting & DYNTICK_TASK_NEST_MASK) {
- rdtp->dynticks_idle_nesting += DYNTICK_TASK_NEST_VALUE;
- WARN_ON_ONCE(rdtp->dynticks_idle_nesting <= 0);
- return; /* Already non-idle. */
- } else {
- rdtp->dynticks_idle_nesting = DYNTICK_TASK_EXIT_IDLE;
- }
- }
-
- /* Record end of idle period. */
- smp_mb__before_atomic();
- atomic_inc(&rdtp->dynticks_idle);
- smp_mb__after_atomic();
- WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks_idle) & 0x1));
-
- /*
- * If we are the timekeeping CPU, we are permitted to be non-idle
- * during a system-idle state. This must be the case, because
- * the timekeeping CPU has to take scheduling-clock interrupts
- * during the time that the system is transitioning to full
- * system-idle state. This means that the timekeeping CPU must
- * invoke rcu_sysidle_force_exit() directly if it does anything
- * more than take a scheduling-clock interrupt.
- */
- if (smp_processor_id() == tick_do_timer_cpu)
- return;
-
- /* Update system-idle state: We are clearly no longer fully idle! */
- rcu_sysidle_force_exit();
-}
-
-/*
- * Check to see if the current CPU is idle. Note that usermode execution
- * does not count as idle. The caller must have disabled interrupts,
- * and must be running on tick_do_timer_cpu.
- */
-static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
- unsigned long *maxj)
-{
- int cur;
- unsigned long j;
- struct rcu_dynticks *rdtp = rdp->dynticks;
-
- RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sysidle_check_cpu() invoked with irqs enabled!!!");
-
- /* If there are no nohz_full= CPUs, don't check system-wide idleness. */
- if (!tick_nohz_full_enabled())
- return;
-
- /*
- * If some other CPU has already reported non-idle, if this is
- * not the flavor of RCU that tracks sysidle state, or if this
- * is an offline or the timekeeping CPU, nothing to do.
- */
- if (!*isidle || rdp->rsp != rcu_state_p ||
- cpu_is_offline(rdp->cpu) || rdp->cpu == tick_do_timer_cpu)
- return;
- /* Verify affinity of current kthread. */
- WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu);
-
- /* Pick up current idle and NMI-nesting counter and check. */
- cur = atomic_read(&rdtp->dynticks_idle);
- if (cur & 0x1) {
- *isidle = false; /* We are not idle! */
- return;
- }
- smp_mb(); /* Read counters before timestamps. */
-
- /* Pick up timestamps. */
- j = READ_ONCE(rdtp->dynticks_idle_jiffies);
- /* If this CPU entered idle more recently, update maxj timestamp. */
- if (ULONG_CMP_LT(*maxj, j))
- *maxj = j;
-}
-
-/*
- * Is this the flavor of RCU that is handling full-system idle?
- */
-static bool is_sysidle_rcu_state(struct rcu_state *rsp)
-{
- return rsp == rcu_state_p;
-}
-
-/*
- * Return a delay in jiffies based on the number of CPUs, rcu_node
- * leaf fanout, and jiffies tick rate. The idea is to allow larger
- * systems more time to transition to full-idle state in order to
- * avoid the cache thrashing that otherwise occur on the state variable.
- * Really small systems (less than a couple of tens of CPUs) should
- * instead use a single global atomically incremented counter, and later
- * versions of this will automatically reconfigure themselves accordingly.
- */
-static unsigned long rcu_sysidle_delay(void)
-{
- if (nr_cpu_ids <= CONFIG_NO_HZ_FULL_SYSIDLE_SMALL)
- return 0;
- return DIV_ROUND_UP(nr_cpu_ids * HZ, rcu_fanout_leaf * 1000);
-}
-
-/*
- * Advance the full-system-idle state. This is invoked when all of
- * the non-timekeeping CPUs are idle.
- */
-static void rcu_sysidle(unsigned long j)
-{
- /* Check the current state. */
- switch (READ_ONCE(full_sysidle_state)) {
- case RCU_SYSIDLE_NOT:
-
- /* First time all are idle, so note a short idle period. */
- WRITE_ONCE(full_sysidle_state, RCU_SYSIDLE_SHORT);
- break;
-
- case RCU_SYSIDLE_SHORT:
-
- /*
- * Idle for a bit, time to advance to next state?
- * cmpxchg failure means race with non-idle, let them win.
- */
- if (ULONG_CMP_GE(jiffies, j + rcu_sysidle_delay()))
- (void)cmpxchg(&full_sysidle_state,
- RCU_SYSIDLE_SHORT, RCU_SYSIDLE_LONG);
- break;
-
- case RCU_SYSIDLE_LONG:
-
- /*
- * Do an additional check pass before advancing to full.
- * cmpxchg failure means race with non-idle, let them win.
- */
- if (ULONG_CMP_GE(jiffies, j + rcu_sysidle_delay()))
- (void)cmpxchg(&full_sysidle_state,
- RCU_SYSIDLE_LONG, RCU_SYSIDLE_FULL);
- break;
-
- default:
- break;
- }
-}
-
-/*
- * Found a non-idle non-timekeeping CPU, so kick the system-idle state
- * back to the beginning.
- */
-static void rcu_sysidle_cancel(void)
-{
- smp_mb();
- if (full_sysidle_state > RCU_SYSIDLE_SHORT)
- WRITE_ONCE(full_sysidle_state, RCU_SYSIDLE_NOT);
-}
-
-/*
- * Update the sysidle state based on the results of a force-quiescent-state
- * scan of the CPUs' dyntick-idle state.
- */
-static void rcu_sysidle_report(struct rcu_state *rsp, int isidle,
- unsigned long maxj, bool gpkt)
-{
- if (rsp != rcu_state_p)
- return; /* Wrong flavor, ignore. */
- if (gpkt && nr_cpu_ids <= CONFIG_NO_HZ_FULL_SYSIDLE_SMALL)
- return; /* Running state machine from timekeeping CPU. */
- if (isidle)
- rcu_sysidle(maxj); /* More idle! */
- else
- rcu_sysidle_cancel(); /* Idle is over. */
-}
-
-/*
- * Wrapper for rcu_sysidle_report() when called from the grace-period
- * kthread's context.
- */
-static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle,
- unsigned long maxj)
-{
- /* If there are no nohz_full= CPUs, no need to track this. */
- if (!tick_nohz_full_enabled())
- return;
-
- rcu_sysidle_report(rsp, isidle, maxj, true);
-}
-
-/* Callback and function for forcing an RCU grace period. */
-struct rcu_sysidle_head {
- struct rcu_head rh;
- int inuse;
-};
-
-static void rcu_sysidle_cb(struct rcu_head *rhp)
-{
- struct rcu_sysidle_head *rshp;
-
- /*
- * The following memory barrier is needed to replace the
- * memory barriers that would normally be in the memory
- * allocator.
- */
- smp_mb(); /* grace period precedes setting inuse. */
-
- rshp = container_of(rhp, struct rcu_sysidle_head, rh);
- WRITE_ONCE(rshp->inuse, 0);
-}
-
-/*
- * Check to see if the system is fully idle, other than the timekeeping CPU.
- * The caller must have disabled interrupts. This is not intended to be
- * called unless tick_nohz_full_enabled().
- */
-bool rcu_sys_is_idle(void)
-{
- static struct rcu_sysidle_head rsh;
- int rss = READ_ONCE(full_sysidle_state);
-
- RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sys_is_idle() invoked with irqs enabled!!!");
-
- if (WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu))
- return false;
-
- /* Handle small-system case by doing a full scan of CPUs. */
- if (nr_cpu_ids <= CONFIG_NO_HZ_FULL_SYSIDLE_SMALL) {
- int oldrss = rss - 1;
-
- /*
- * One pass to advance to each state up to _FULL.
- * Give up if any pass fails to advance the state.
- */
- while (rss < RCU_SYSIDLE_FULL && oldrss < rss) {
- int cpu;
- bool isidle = true;
- unsigned long maxj = jiffies - ULONG_MAX / 4;
- struct rcu_data *rdp;
-
- /* Scan all the CPUs looking for nonidle CPUs. */
- for_each_possible_cpu(cpu) {
- rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
- rcu_sysidle_check_cpu(rdp, &isidle, &maxj);
- if (!isidle)
- break;
- }
- rcu_sysidle_report(rcu_state_p, isidle, maxj, false);
- oldrss = rss;
- rss = READ_ONCE(full_sysidle_state);
- }
- }
-
- /* If this is the first observation of an idle period, record it. */
- if (rss == RCU_SYSIDLE_FULL) {
- rss = cmpxchg(&full_sysidle_state,
- RCU_SYSIDLE_FULL, RCU_SYSIDLE_FULL_NOTED);
- return rss == RCU_SYSIDLE_FULL;
- }
-
- smp_mb(); /* ensure rss load happens before later caller actions. */
-
- /* If already fully idle, tell the caller (in case of races). */
- if (rss == RCU_SYSIDLE_FULL_NOTED)
- return true;
-
- /*
- * If we aren't there yet, and a grace period is not in flight,
- * initiate a grace period. Either way, tell the caller that
- * we are not there yet. We use an xchg() rather than an assignment
- * to make up for the memory barriers that would otherwise be
- * provided by the memory allocator.
- */
- if (nr_cpu_ids > CONFIG_NO_HZ_FULL_SYSIDLE_SMALL &&
- !rcu_gp_in_progress(rcu_state_p) &&
- !rsh.inuse && xchg(&rsh.inuse, 1) == 0)
- call_rcu(&rsh.rh, rcu_sysidle_cb);
- return false;
-}
-
-/*
- * Initialize dynticks sysidle state for CPUs coming online.
- */
-static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp)
-{
- rdtp->dynticks_idle_nesting = DYNTICK_TASK_NEST_VALUE;
-}
-
-#else /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
-
-static void rcu_sysidle_enter(int irq)
-{
-}
-
-static void rcu_sysidle_exit(int irq)
-{
-}
-
-static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
- unsigned long *maxj)
-{
-}
-
-static bool is_sysidle_rcu_state(struct rcu_state *rsp)
-{
- return false;
-}
-
-static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle,
- unsigned long maxj)
-{
-}
-
-static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
-
/*
* Is this CPU a NO_HZ_FULL CPU that should ignore RCU so that the
* grace-period kthread will do force_quiescent_state() processing?
if (!tick_nohz_full_enabled())
return;
-#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
- cpu = tick_do_timer_cpu;
- if (cpu >= 0 && cpu < nr_cpu_ids)
- set_cpus_allowed_ptr(current, cpumask_of(cpu));
-#else /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
housekeeping_affine(current);
-#endif /* #else #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
}
/* Record the current task on dyntick-idle entry. */
projects / platform / kernel / linux-rpi.git / commitdiff