*
* Caller must disable preemption.
*/
-static void rcu_preempt_note_context_switch(int cpu)
+void rcu_preempt_note_context_switch(void)
{
struct task_struct *t = current;
unsigned long flags;
(t->rcu_read_unlock_special & RCU_READ_UNLOCK_BLOCKED) == 0) {
/* Possibly blocking in an RCU read-side critical section. */
- rdp = per_cpu_ptr(rcu_preempt_state.rda, cpu);
+ rdp = __this_cpu_ptr(rcu_preempt_state.rda);
rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
* means that we continue to block the current grace period.
*/
local_irq_save(flags);
- rcu_preempt_qs(cpu);
+ rcu_preempt_qs(smp_processor_id());
local_irq_restore(flags);
}
rcu_init_one(&rcu_preempt_state, &rcu_preempt_data);
}
-/*
- * Check for a task exiting while in a preemptible-RCU read-side
- * critical section, clean up if so. No need to issue warnings,
- * as debug_check_no_locks_held() already does this if lockdep
- * is enabled.
- */
-void exit_rcu(void)
-{
- struct task_struct *t = current;
-
- if (t->rcu_read_lock_nesting == 0)
- return;
- t->rcu_read_lock_nesting = 1;
- __rcu_read_unlock();
-}
-
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
static struct rcu_state *rcu_state = &rcu_sched_state;
}
EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
-/*
- * Because preemptible RCU does not exist, we never have to check for
- * CPUs being in quiescent states.
- */
-static void rcu_preempt_note_context_switch(int cpu)
-{
-}
-
/*
* Because preemptible RCU does not exist, there are never any preempted
* RCU readers.
#define RCU_IDLE_GP_DELAY 6 /* Roughly one grace period. */
#define RCU_IDLE_LAZY_GP_DELAY (6 * HZ) /* Roughly six seconds. */
+/* Loop counter for rcu_prepare_for_idle(). */
static DEFINE_PER_CPU(int, rcu_dyntick_drain);
+/* If rcu_dyntick_holdoff==jiffies, don't try to enter dyntick-idle mode. */
static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
+/* Timer to awaken the CPU if it enters dyntick-idle mode with callbacks. */
static DEFINE_PER_CPU(struct timer_list, rcu_idle_gp_timer);
+/* Scheduled expiry time for rcu_idle_gp_timer to allow reposting. */
static DEFINE_PER_CPU(unsigned long, rcu_idle_gp_timer_expires);
+/* Enable special processing on first attempt to enter dyntick-idle mode. */
static DEFINE_PER_CPU(bool, rcu_idle_first_pass);
+/* Running count of non-lazy callbacks posted, never decremented. */
static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted);
+/* Snapshot of rcu_nonlazy_posted to detect meaningful exits from idle. */
static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted_snap);
/*
rcu_preempt_cpu_has_nonlazy_callbacks(cpu);
}
+/*
+ * Handler for smp_call_function_single(). The only point of this
+ * handler is to wake the CPU up, so the handler does only tracing.
+ */
+void rcu_idle_demigrate(void *unused)
+{
+ trace_rcu_prep_idle("Demigrate");
+}
+
/*
* Timer handler used to force CPU to start pushing its remaining RCU
* callbacks in the case where it entered dyntick-idle mode with callbacks
* pending. The hander doesn't really need to do anything because the
* real work is done upon re-entry to idle, or by the next scheduling-clock
* interrupt should idle not be re-entered.
+ *
+ * One special case: the timer gets migrated without awakening the CPU
+ * on which the timer was scheduled on. In this case, we must wake up
+ * that CPU. We do so with smp_call_function_single().
*/
-static void rcu_idle_gp_timer_func(unsigned long unused)
+static void rcu_idle_gp_timer_func(unsigned long cpu_in)
{
+ int cpu = (int)cpu_in;
+
trace_rcu_prep_idle("Timer");
+ if (cpu != smp_processor_id())
+ smp_call_function_single(cpu, rcu_idle_demigrate, NULL, 0);
+ else
+ WARN_ON_ONCE(1); /* Getting here can hang the system... */
}
/*
*/
static void rcu_prepare_for_idle_init(int cpu)
{
+ per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
setup_timer(&per_cpu(rcu_idle_gp_timer, cpu),
- rcu_idle_gp_timer_func, 0);
+ rcu_idle_gp_timer_func, cpu);
+ per_cpu(rcu_idle_gp_timer_expires, cpu) = jiffies - 1;
+ per_cpu(rcu_idle_first_pass, cpu) = 1;
}
/*
*/
static void rcu_prepare_for_idle(int cpu)
{
+ struct timer_list *tp;
+
/*
* If this is an idle re-entry, for example, due to use of
* RCU_NONIDLE() or the new idle-loop tracing API within the idle
if (!per_cpu(rcu_idle_first_pass, cpu) &&
(per_cpu(rcu_nonlazy_posted, cpu) ==
per_cpu(rcu_nonlazy_posted_snap, cpu))) {
- if (rcu_cpu_has_callbacks(cpu))
- mod_timer(&per_cpu(rcu_idle_gp_timer, cpu),
- per_cpu(rcu_idle_gp_timer_expires, cpu));
+ if (rcu_cpu_has_callbacks(cpu)) {
+ tp = &per_cpu(rcu_idle_gp_timer, cpu);
+ mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
+ }
return;
}
per_cpu(rcu_idle_first_pass, cpu) = 0;
else
per_cpu(rcu_idle_gp_timer_expires, cpu) =
jiffies + RCU_IDLE_LAZY_GP_DELAY;
- mod_timer(&per_cpu(rcu_idle_gp_timer, cpu),
- per_cpu(rcu_idle_gp_timer_expires, cpu));
+ tp = &per_cpu(rcu_idle_gp_timer, cpu);
+ mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
per_cpu(rcu_nonlazy_posted_snap, cpu) =
per_cpu(rcu_nonlazy_posted, cpu);
return; /* Nothing more to do immediately. */
}
/*
- * Keep a running count of callbacks posted so that rcu_prepare_for_idle()
- * can detect when something out of the idle loop posts a callback.
- * Of course, it had better do so either from a trace event designed to
- * be called from idle or from within RCU_NONIDLE().
+ * Keep a running count of the number of non-lazy callbacks posted
+ * on this CPU. This running counter (which is never decremented) allows
+ * rcu_prepare_for_idle() to detect when something out of the idle loop
+ * posts a callback, even if an equal number of callbacks are invoked.
+ * Of course, callbacks should only be posted from within a trace event
+ * designed to be called from idle or from within RCU_NONIDLE().
*/
static void rcu_idle_count_callbacks_posted(void)
{
projects / karo-tx-linux.git / blobdiff