* For detailed explanation of Read-Copy Update mechanism see -
* Documentation/RCU
*/
-#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/rcupdate.h>
#include <linux/kernel.h>
-#include <linux/module.h>
+#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/cpu.h>
#include <linux/prefetch.h>
-/* Controls for rcu_kthread() kthread, replacing RCU_SOFTIRQ used previously. */
-static struct task_struct *rcu_kthread_task;
-static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq);
-static unsigned long have_rcu_kthread_work;
+#ifdef CONFIG_RCU_TRACE
+#include <trace/events/rcu.h>
+#endif /* #else #ifdef CONFIG_RCU_TRACE */
+
+#include "rcu.h"
/* Forward declarations for rcutiny_plugin.h. */
struct rcu_ctrlblk;
-static void invoke_rcu_kthread(void);
-static void rcu_process_callbacks(struct rcu_ctrlblk *rcp);
-static int rcu_kthread(void *arg);
+static void invoke_rcu_callbacks(void);
+static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp);
+static void rcu_process_callbacks(struct softirq_action *unused);
static void __call_rcu(struct rcu_head *head,
void (*func)(struct rcu_head *rcu),
struct rcu_ctrlblk *rcp);
#include "rcutiny_plugin.h"
-#ifdef CONFIG_NO_HZ
+static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
-static long rcu_dynticks_nesting = 1;
+/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */
+static void rcu_idle_enter_common(long long oldval)
+{
+ if (rcu_dynticks_nesting) {
+ RCU_TRACE(trace_rcu_dyntick("--=",
+ oldval, rcu_dynticks_nesting));
+ return;
+ }
+ RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
+ if (!is_idle_task(current)) {
+ struct task_struct *idle = idle_task(smp_processor_id());
+
+ RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task",
+ oldval, rcu_dynticks_nesting));
+ ftrace_dump(DUMP_ALL);
+ WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
+ current->pid, current->comm,
+ idle->pid, idle->comm); /* must be idle task! */
+ }
+ rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
+}
/*
- * Enter dynticks-idle mode, which is an extended quiescent state
- * if we have fully entered that mode (i.e., if the new value of
- * dynticks_nesting is zero).
+ * Enter idle, which is an extended quiescent state if we have fully
+ * entered that mode (i.e., if the new value of dynticks_nesting is zero).
*/
-void rcu_enter_nohz(void)
+void rcu_idle_enter(void)
{
- if (--rcu_dynticks_nesting == 0)
- rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
+ unsigned long flags;
+ long long oldval;
+
+ local_irq_save(flags);
+ oldval = rcu_dynticks_nesting;
+ WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
+ if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) ==
+ DYNTICK_TASK_NEST_VALUE)
+ rcu_dynticks_nesting = 0;
+ else
+ rcu_dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
+ rcu_idle_enter_common(oldval);
+ local_irq_restore(flags);
}
+EXPORT_SYMBOL_GPL(rcu_idle_enter);
/*
- * Exit dynticks-idle mode, so that we are no longer in an extended
- * quiescent state.
+ * Exit an interrupt handler towards idle.
+ */
+void rcu_irq_exit(void)
+{
+ unsigned long flags;
+ long long oldval;
+
+ local_irq_save(flags);
+ oldval = rcu_dynticks_nesting;
+ rcu_dynticks_nesting--;
+ WARN_ON_ONCE(rcu_dynticks_nesting < 0);
+ rcu_idle_enter_common(oldval);
+ local_irq_restore(flags);
+}
+
+/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */
+static void rcu_idle_exit_common(long long oldval)
+{
+ if (oldval) {
+ RCU_TRACE(trace_rcu_dyntick("++=",
+ oldval, rcu_dynticks_nesting));
+ return;
+ }
+ RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting));
+ if (!is_idle_task(current)) {
+ struct task_struct *idle = idle_task(smp_processor_id());
+
+ RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task",
+ oldval, rcu_dynticks_nesting));
+ ftrace_dump(DUMP_ALL);
+ WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
+ current->pid, current->comm,
+ idle->pid, idle->comm); /* must be idle task! */
+ }
+}
+
+/*
+ * Exit idle, so that we are no longer in an extended quiescent state.
*/
-void rcu_exit_nohz(void)
+void rcu_idle_exit(void)
{
+ unsigned long flags;
+ long long oldval;
+
+ local_irq_save(flags);
+ oldval = rcu_dynticks_nesting;
+ WARN_ON_ONCE(rcu_dynticks_nesting < 0);
+ if (rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK)
+ rcu_dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
+ else
+ rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
+ rcu_idle_exit_common(oldval);
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(rcu_idle_exit);
+
+/*
+ * Enter an interrupt handler, moving away from idle.
+ */
+void rcu_irq_enter(void)
+{
+ unsigned long flags;
+ long long oldval;
+
+ local_irq_save(flags);
+ oldval = rcu_dynticks_nesting;
rcu_dynticks_nesting++;
+ WARN_ON_ONCE(rcu_dynticks_nesting == 0);
+ rcu_idle_exit_common(oldval);
+ local_irq_restore(flags);
+}
+
+#ifdef CONFIG_PROVE_RCU
+
+/*
+ * Test whether RCU thinks that the current CPU is idle.
+ */
+int rcu_is_cpu_idle(void)
+{
+ return !rcu_dynticks_nesting;
}
+EXPORT_SYMBOL(rcu_is_cpu_idle);
-#endif /* #ifdef CONFIG_NO_HZ */
+#endif /* #ifdef CONFIG_PROVE_RCU */
+
+/*
+ * Test whether the current CPU was interrupted from idle. Nested
+ * interrupts don't count, we must be running at the first interrupt
+ * level.
+ */
+int rcu_is_cpu_rrupt_from_idle(void)
+{
+ return rcu_dynticks_nesting <= 0;
+}
/*
* Helper function for rcu_sched_qs() and rcu_bh_qs().
}
/*
- * Wake up rcu_kthread() to process callbacks now eligible for invocation
- * or to boost readers.
- */
-static void invoke_rcu_kthread(void)
-{
- have_rcu_kthread_work = 1;
- wake_up(&rcu_kthread_wq);
-}
-
-/*
* Record an rcu quiescent state. And an rcu_bh quiescent state while we
* are at it, given that any rcu quiescent state is also an rcu_bh
* quiescent state. Use "+" instead of "||" to defeat short circuiting.
local_irq_save(flags);
if (rcu_qsctr_help(&rcu_sched_ctrlblk) +
rcu_qsctr_help(&rcu_bh_ctrlblk))
- invoke_rcu_kthread();
+ invoke_rcu_callbacks();
local_irq_restore(flags);
}
local_irq_save(flags);
if (rcu_qsctr_help(&rcu_bh_ctrlblk))
- invoke_rcu_kthread();
+ invoke_rcu_callbacks();
local_irq_restore(flags);
}
/*
* Check to see if the scheduling-clock interrupt came from an extended
- * quiescent state, and, if so, tell RCU about it.
+ * quiescent state, and, if so, tell RCU about it. This function must
+ * be called from hardirq context. It is normally called from the
+ * scheduling-clock interrupt.
*/
void rcu_check_callbacks(int cpu, int user)
{
- if (user ||
- (idle_cpu(cpu) &&
- !in_softirq() &&
- hardirq_count() <= (1 << HARDIRQ_SHIFT)))
+ if (user || rcu_is_cpu_rrupt_from_idle())
rcu_sched_qs(cpu);
else if (!in_softirq())
rcu_bh_qs(cpu);
* Invoke the RCU callbacks on the specified rcu_ctrlkblk structure
* whose grace period has elapsed.
*/
-static void rcu_process_callbacks(struct rcu_ctrlblk *rcp)
+static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
{
+ char *rn = NULL;
struct rcu_head *next, *list;
unsigned long flags;
RCU_TRACE(int cb_count = 0);
/* If no RCU callbacks ready to invoke, just return. */
- if (&rcp->rcucblist == rcp->donetail)
+ if (&rcp->rcucblist == rcp->donetail) {
+ RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, 0, -1));
+ RCU_TRACE(trace_rcu_batch_end(rcp->name, 0,
+ ACCESS_ONCE(rcp->rcucblist),
+ need_resched(),
+ is_idle_task(current),
+ rcu_is_callbacks_kthread()));
return;
+ }
/* Move the ready-to-invoke callbacks to a local list. */
local_irq_save(flags);
+ RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, rcp->qlen, -1));
list = rcp->rcucblist;
rcp->rcucblist = *rcp->donetail;
*rcp->donetail = NULL;
local_irq_restore(flags);
/* Invoke the callbacks on the local list. */
+ RCU_TRACE(rn = rcp->name);
while (list) {
next = list->next;
prefetch(next);
debug_rcu_head_unqueue(list);
local_bh_disable();
- __rcu_reclaim(list);
+ __rcu_reclaim(rn, list);
local_bh_enable();
list = next;
RCU_TRACE(cb_count++);
}
RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count));
+ RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count, 0, need_resched(),
+ is_idle_task(current),
+ rcu_is_callbacks_kthread()));
}
-/*
- * This kthread invokes RCU callbacks whose grace periods have
- * elapsed. It is awakened as needed, and takes the place of the
- * RCU_SOFTIRQ that was used previously for this purpose.
- * This is a kthread, but it is never stopped, at least not until
- * the system goes down.
- */
-static int rcu_kthread(void *arg)
+static void rcu_process_callbacks(struct softirq_action *unused)
{
- 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(&rcu_sched_ctrlblk);
- rcu_process_callbacks(&rcu_bh_ctrlblk);
- rcu_preempt_process_callbacks();
- }
- schedule_timeout_interruptible(1); /* Leave CPU for others. */
- }
-
- return 0; /* Not reached, but needed to shut gcc up. */
+ __rcu_process_callbacks(&rcu_sched_ctrlblk);
+ __rcu_process_callbacks(&rcu_bh_ctrlblk);
+ rcu_preempt_process_callbacks();
}
/*
*/
void synchronize_sched(void)
{
+ rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
+ !lock_is_held(&rcu_lock_map) &&
+ !lock_is_held(&rcu_sched_lock_map),
+ "Illegal synchronize_sched() in RCU read-side critical section");
cond_resched();
}
EXPORT_SYMBOL_GPL(synchronize_sched);
__call_rcu(head, func, &rcu_bh_ctrlblk);
}
EXPORT_SYMBOL_GPL(call_rcu_bh);
-
-/*
- * 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);
projects / linux-flexiantxendom0-3.2.10.git / blobdiff