summaryrefslogtreecommitdiffstats
path: root/kernel/rcutiny_plugin.h
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/rcutiny_plugin.h')
-rw-r--r--kernel/rcutiny_plugin.h135
1 files changed, 88 insertions, 47 deletions
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index f259c676195..2b0484a5dc2 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -23,32 +23,30 @@
*/
#include <linux/kthread.h>
+#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
-#ifdef CONFIG_RCU_TRACE
-#define RCU_TRACE(stmt) stmt
-#else /* #ifdef CONFIG_RCU_TRACE */
-#define RCU_TRACE(stmt)
-#endif /* #else #ifdef CONFIG_RCU_TRACE */
-
/* Global control variables for rcupdate callback mechanism. */
struct rcu_ctrlblk {
struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */
struct rcu_head **donetail; /* ->next pointer of last "done" CB. */
struct rcu_head **curtail; /* ->next pointer of last CB. */
RCU_TRACE(long qlen); /* Number of pending CBs. */
+ RCU_TRACE(char *name); /* Name of RCU type. */
};
/* Definition for rcupdate control block. */
static struct rcu_ctrlblk rcu_sched_ctrlblk = {
.donetail = &rcu_sched_ctrlblk.rcucblist,
.curtail = &rcu_sched_ctrlblk.rcucblist,
+ RCU_TRACE(.name = "rcu_sched")
};
static struct rcu_ctrlblk rcu_bh_ctrlblk = {
.donetail = &rcu_bh_ctrlblk.rcucblist,
.curtail = &rcu_bh_ctrlblk.rcucblist,
+ RCU_TRACE(.name = "rcu_bh")
};
#ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -131,6 +129,7 @@ static struct rcu_preempt_ctrlblk rcu_preempt_ctrlblk = {
.rcb.curtail = &rcu_preempt_ctrlblk.rcb.rcucblist,
.nexttail = &rcu_preempt_ctrlblk.rcb.rcucblist,
.blkd_tasks = LIST_HEAD_INIT(rcu_preempt_ctrlblk.blkd_tasks),
+ RCU_TRACE(.rcb.name = "rcu_preempt")
};
static int rcu_preempted_readers_exp(void);
@@ -247,6 +246,13 @@ static void show_tiny_preempt_stats(struct seq_file *m)
#include "rtmutex_common.h"
+#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO
+
+/* Controls for rcu_kthread() kthread. */
+static struct task_struct *rcu_kthread_task;
+static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq);
+static unsigned long have_rcu_kthread_work;
+
/*
* Carry out RCU priority boosting on the task indicated by ->boost_tasks,
* and advance ->boost_tasks to the next task in the ->blkd_tasks list.
@@ -334,7 +340,7 @@ static int rcu_initiate_boost(void)
if (rcu_preempt_ctrlblk.exp_tasks == NULL)
rcu_preempt_ctrlblk.boost_tasks =
rcu_preempt_ctrlblk.gp_tasks;
- invoke_rcu_kthread();
+ invoke_rcu_callbacks();
} else
RCU_TRACE(rcu_initiate_boost_trace());
return 1;
@@ -353,14 +359,6 @@ static void rcu_preempt_boost_start_gp(void)
#else /* #ifdef CONFIG_RCU_BOOST */
/*
- * If there is no RCU priority boosting, we don't boost.
- */
-static int rcu_boost(void)
-{
- return 0;
-}
-
-/*
* If there is no RCU priority boosting, we don't initiate boosting,
* but we do indicate whether there are blocked readers blocking the
* current grace period.
@@ -427,7 +425,7 @@ static void rcu_preempt_cpu_qs(void)
/* If there are done callbacks, cause them to be invoked. */
if (*rcu_preempt_ctrlblk.rcb.donetail != NULL)
- invoke_rcu_kthread();
+ invoke_rcu_callbacks();
}
/*
@@ -648,7 +646,7 @@ static void rcu_preempt_check_callbacks(void)
rcu_preempt_cpu_qs();
if (&rcu_preempt_ctrlblk.rcb.rcucblist !=
rcu_preempt_ctrlblk.rcb.donetail)
- invoke_rcu_kthread();
+ invoke_rcu_callbacks();
if (rcu_preempt_gp_in_progress() &&
rcu_cpu_blocking_cur_gp() &&
rcu_preempt_running_reader())
@@ -674,7 +672,7 @@ static void rcu_preempt_remove_callbacks(struct rcu_ctrlblk *rcp)
*/
static void rcu_preempt_process_callbacks(void)
{
- rcu_process_callbacks(&rcu_preempt_ctrlblk.rcb);
+ __rcu_process_callbacks(&rcu_preempt_ctrlblk.rcb);
}
/*
@@ -697,20 +695,6 @@ void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
EXPORT_SYMBOL_GPL(call_rcu);
-void rcu_barrier(void)
-{
- struct rcu_synchronize rcu;
-
- init_rcu_head_on_stack(&rcu.head);
- init_completion(&rcu.completion);
- /* Will wake me after RCU finished. */
- call_rcu(&rcu.head, wakeme_after_rcu);
- /* Wait for it. */
- wait_for_completion(&rcu.completion);
- destroy_rcu_head_on_stack(&rcu.head);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier);
-
/*
* synchronize_rcu - wait until a grace period has elapsed.
*
@@ -864,15 +848,6 @@ static void show_tiny_preempt_stats(struct seq_file *m)
#endif /* #ifdef CONFIG_RCU_TRACE */
/*
- * Because preemptible RCU does not exist, it is never necessary to
- * boost preempted RCU readers.
- */
-static int rcu_boost(void)
-{
- return 0;
-}
-
-/*
* Because preemptible RCU does not exist, it never has any callbacks
* to check.
*/
@@ -898,6 +873,78 @@ static void rcu_preempt_process_callbacks(void)
#endif /* #else #ifdef CONFIG_TINY_PREEMPT_RCU */
+#ifdef CONFIG_RCU_BOOST
+
+/*
+ * Wake up rcu_kthread() to process callbacks now eligible for invocation
+ * or to boost readers.
+ */
+static void invoke_rcu_callbacks(void)
+{
+ have_rcu_kthread_work = 1;
+ wake_up(&rcu_kthread_wq);
+}
+
+/*
+ * This kthread invokes RCU callbacks whose grace periods have
+ * elapsed. It is awakened as needed, and takes the place of the
+ * RCU_SOFTIRQ that is used for this purpose when boosting is disabled.
+ * This is a kthread, but it is never stopped, at least not until
+ * the system goes down.
+ */
+static int rcu_kthread(void *arg)
+{
+ unsigned long work;
+ unsigned long morework;
+ unsigned long flags;
+
+ for (;;) {
+ wait_event_interruptible(rcu_kthread_wq,
+ have_rcu_kthread_work != 0);
+ morework = rcu_boost();
+ local_irq_save(flags);
+ work = have_rcu_kthread_work;
+ have_rcu_kthread_work = morework;
+ local_irq_restore(flags);
+ if (work)
+ rcu_process_callbacks(NULL);
+ schedule_timeout_interruptible(1); /* Leave CPU for others. */
+ }
+
+ return 0; /* Not reached, but needed to shut gcc up. */
+}
+
+/*
+ * Spawn the kthread that invokes RCU callbacks.
+ */
+static int __init rcu_spawn_kthreads(void)
+{
+ struct sched_param sp;
+
+ rcu_kthread_task = kthread_run(rcu_kthread, NULL, "rcu_kthread");
+ sp.sched_priority = RCU_BOOST_PRIO;
+ sched_setscheduler_nocheck(rcu_kthread_task, SCHED_FIFO, &sp);
+ return 0;
+}
+early_initcall(rcu_spawn_kthreads);
+
+#else /* #ifdef CONFIG_RCU_BOOST */
+
+/*
+ * Start up softirq processing of callbacks.
+ */
+void invoke_rcu_callbacks(void)
+{
+ raise_softirq(RCU_SOFTIRQ);
+}
+
+void rcu_init(void)
+{
+ open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+}
+
+#endif /* #else #ifdef CONFIG_RCU_BOOST */
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#include <linux/kernel_stat.h>
@@ -913,12 +960,6 @@ void __init rcu_scheduler_starting(void)
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
-#ifdef CONFIG_RCU_BOOST
-#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO
-#else /* #ifdef CONFIG_RCU_BOOST */
-#define RCU_BOOST_PRIO 1
-#endif /* #else #ifdef CONFIG_RCU_BOOST */
-
#ifdef CONFIG_RCU_TRACE
#ifdef CONFIG_RCU_BOOST
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-22 22:54:31 +0000