static int rcu_pending(void);
/*
- * Return the number of RCU-sched batches processed thus far for debug & stats.
+ * Return the number of RCU batches started thus far for debug & stats.
*/
-long rcu_batches_completed_sched(void)
+unsigned long rcu_batches_started(void)
+{
+ return rcu_state_p->gpnum;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_started);
+
+/*
+ * Return the number of RCU-sched batches started thus far for debug & stats.
+ */
+unsigned long rcu_batches_started_sched(void)
+{
+ return rcu_sched_state.gpnum;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_started_sched);
+
+/*
+ * Return the number of RCU BH batches started thus far for debug & stats.
+ */
+unsigned long rcu_batches_started_bh(void)
+{
+ return rcu_bh_state.gpnum;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_started_bh);
+
+/*
+ * Return the number of RCU batches completed thus far for debug & stats.
+ */
+unsigned long rcu_batches_completed(void)
+{
+ return rcu_state_p->completed;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_completed);
+
+/*
+ * Return the number of RCU-sched batches completed thus far for debug & stats.
+ */
+unsigned long rcu_batches_completed_sched(void)
{
return rcu_sched_state.completed;
}
EXPORT_SYMBOL_GPL(rcu_batches_completed_sched);
/*
- * Return the number of RCU BH batches processed thus far for debug & stats.
+ * Return the number of RCU BH batches completed thus far for debug & stats.
*/
-long rcu_batches_completed_bh(void)
+unsigned long rcu_batches_completed_bh(void)
{
return rcu_bh_state.completed;
}
}
}
-/*
- * This function really isn't for public consumption, but RCU is special in
- * that context switches can allow the state machine to make progress.
- */
-extern void resched_cpu(int cpu);
-
/*
* Return true if the specified CPU has passed through a quiescent
* state by virtue of being in or having passed through an dynticks
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
- /*
- * Now rat on any tasks that got kicked up to the root rcu_node
- * due to CPU offlining.
- */
- rnp = rcu_get_root(rsp);
- raw_spin_lock_irqsave(&rnp->lock, flags);
- ndetected += rcu_print_task_stall(rnp);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
-
print_cpu_stall_info_end();
for_each_possible_cpu(cpu)
totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen;
TPS("cpuofl"));
}
+/*
+ * All CPUs for the specified rcu_node structure have gone offline,
+ * and all tasks that were preempted within an RCU read-side critical
+ * section while running on one of those CPUs have since exited their RCU
+ * read-side critical section. Some other CPU is reporting this fact with
+ * the specified rcu_node structure's ->lock held and interrupts disabled.
+ * This function therefore goes up the tree of rcu_node structures,
+ * clearing the corresponding bits in the ->qsmaskinit fields. Note that
+ * the leaf rcu_node structure's ->qsmaskinit field has already been
+ * updated
+ *
+ * This function does check that the specified rcu_node structure has
+ * all CPUs offline and no blocked tasks, so it is OK to invoke it
+ * prematurely. That said, invoking it after the fact will cost you
+ * a needless lock acquisition. So once it has done its work, don't
+ * invoke it again.
+ */
+static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
+{
+ long mask;
+ struct rcu_node *rnp = rnp_leaf;
+
+ if (rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))
+ return;
+ for (;;) {
+ mask = rnp->grpmask;
+ rnp = rnp->parent;
+ if (!rnp)
+ break;
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
+ smp_mb__after_unlock_lock(); /* GP memory ordering. */
+ rnp->qsmaskinit &= ~mask;
+ if (rnp->qsmaskinit) {
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ return;
+ }
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ }
+}
+
/*
* The CPU has been completely removed, and some other CPU is reporting
* this fact from process context. Do the remainder of the cleanup,
static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
{
unsigned long flags;
- unsigned long mask;
- int need_report = 0;
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
rcu_adopt_orphan_cbs(rsp, flags);
+ raw_spin_unlock_irqrestore(&rsp->orphan_lock, flags);
- /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
- mask = rdp->grpmask; /* rnp->grplo is constant. */
- do {
- raw_spin_lock(&rnp->lock); /* irqs already disabled. */
- smp_mb__after_unlock_lock();
- rnp->qsmaskinit &= ~mask;
- if (rnp->qsmaskinit != 0) {
- if (rnp != rdp->mynode)
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
- break;
- }
- if (rnp == rdp->mynode)
- need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
- else
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
- mask = rnp->grpmask;
- rnp = rnp->parent;
- } while (rnp != NULL);
-
- /*
- * We still hold the leaf rcu_node structure lock here, and
- * irqs are still disabled. The reason for this subterfuge is
- * because invoking rcu_report_unblock_qs_rnp() with ->orphan_lock
- * held leads to deadlock.
- */
- raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */
- rnp = rdp->mynode;
- if (need_report & RCU_OFL_TASKS_NORM_GP)
- rcu_report_unblock_qs_rnp(rnp, flags);
- else
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
- if (need_report & RCU_OFL_TASKS_EXP_GP)
- rcu_report_exp_rnp(rsp, rnp, true);
+ /* Remove outgoing CPU from mask in the leaf rcu_node structure. */
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ smp_mb__after_unlock_lock(); /* Enforce GP memory-order guarantee. */
+ rnp->qsmaskinit &= ~rdp->grpmask;
+ if (rnp->qsmaskinit == 0 && !rcu_preempt_has_tasks(rnp))
+ rcu_cleanup_dead_rnp(rnp);
+ rcu_report_qs_rnp(rdp->grpmask, rsp, rnp, flags); /* Rlses rnp->lock. */
WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",
cpu, rdp->qlen, rdp->nxtlist);
{
}
+static void __maybe_unused rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
+{
+}
+
static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
{
}
}
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
- rnp = rcu_get_root(rsp);
- if (rnp->qsmask == 0) {
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock();
- rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
- }
}
/*
* Schedule RCU callback invocation. If the specified type of RCU
* does not support RCU priority boosting, just do a direct call,
* otherwise wake up the per-CPU kernel kthread. Note that because we
- * are running on the current CPU with interrupts disabled, the
+ * are running on the current CPU with softirqs disabled, the
* rcu_cpu_kthread_task cannot disappear out from under us.
*/
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
} else {
_rcu_barrier_trace(rsp, "OnlineNoCB", cpu,
rsp->n_barrier_done);
+ smp_mb__before_atomic();
atomic_inc(&rsp->barrier_cpu_count);
__call_rcu(&rdp->barrier_head,
rcu_barrier_callback, rsp, cpu, 0);
/* Set up local state, ensuring consistent view of global state. */
raw_spin_lock_irqsave(&rnp->lock, flags);
rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
- init_callback_list(rdp);
- rdp->qlen_lazy = 0;
- ACCESS_ONCE(rdp->qlen) = 0;
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
projects / linux-beck.git / blobdiff