Merge branches 'doc.2015.01.07a', 'fixes.2015.01.15a', 'preempt.2015.01.06a', 'srcu...

[cascardo/linux.git] / kernel / rcu / tiny.c

diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 0db5649..cc9ceca 100644 (file)
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -47,54 +47,14 @@ static void __call_rcu(struct rcu_head *head,
                       void (*func)(struct rcu_head *rcu),
                       struct rcu_ctrlblk *rcp);
 
-static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
-
 #include "tiny_plugin.h"
 
-/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcu/tree.c. */
-static void rcu_idle_enter_common(long long newval)
-{
-       if (newval) {
-               RCU_TRACE(trace_rcu_dyntick(TPS("--="),
-                                           rcu_dynticks_nesting, newval));
-               rcu_dynticks_nesting = newval;
-               return;
-       }
-       RCU_TRACE(trace_rcu_dyntick(TPS("Start"),
-                                   rcu_dynticks_nesting, newval));
-       if (IS_ENABLED(CONFIG_RCU_TRACE) && !is_idle_task(current)) {
-               struct task_struct *idle __maybe_unused = idle_task(smp_processor_id());
-
-               RCU_TRACE(trace_rcu_dyntick(TPS("Entry error: not idle task"),
-                                           rcu_dynticks_nesting, newval));
-               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(); /* implies rcu_bh_inc() */
-       barrier();
-       rcu_dynticks_nesting = newval;
-}
-
 /*
  * 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).
+ * entered that mode.
  */
 void rcu_idle_enter(void)
 {
-       unsigned long flags;
-       long long newval;
-
-       local_irq_save(flags);
-       WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
-       if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) ==
-           DYNTICK_TASK_NEST_VALUE)
-               newval = 0;
-       else
-               newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE;
-       rcu_idle_enter_common(newval);
-       local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
@@ -103,55 +63,14 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
  */
 void rcu_irq_exit(void)
 {
-       unsigned long flags;
-       long long newval;
-
-       local_irq_save(flags);
-       newval = rcu_dynticks_nesting - 1;
-       WARN_ON_ONCE(newval < 0);
-       rcu_idle_enter_common(newval);
-       local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_irq_exit);
 
-/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcu/tree.c. */
-static void rcu_idle_exit_common(long long oldval)
-{
-       if (oldval) {
-               RCU_TRACE(trace_rcu_dyntick(TPS("++="),
-                                           oldval, rcu_dynticks_nesting));
-               return;
-       }
-       RCU_TRACE(trace_rcu_dyntick(TPS("End"), oldval, rcu_dynticks_nesting));
-       if (IS_ENABLED(CONFIG_RCU_TRACE) && !is_idle_task(current)) {
-               struct task_struct *idle __maybe_unused = idle_task(smp_processor_id());
-
-               RCU_TRACE(trace_rcu_dyntick(TPS("Exit error: 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_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);
 
@@ -160,15 +79,6 @@ EXPORT_SYMBOL_GPL(rcu_idle_exit);
  */
 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);
 }
 EXPORT_SYMBOL_GPL(rcu_irq_enter);
 
@@ -179,22 +89,12 @@ EXPORT_SYMBOL_GPL(rcu_irq_enter);
  */
 bool notrace __rcu_is_watching(void)
 {
-       return rcu_dynticks_nesting;
+       return true;
 }
 EXPORT_SYMBOL(__rcu_is_watching);
 
 #endif /* defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
 
-/*
- * Test whether the current CPU was interrupted from idle.  Nested
- * interrupts don't count, we must be running at the first interrupt
- * level.
- */
-static int rcu_is_cpu_rrupt_from_idle(void)
-{
-       return rcu_dynticks_nesting <= 1;
-}
-
 /*
  * Helper function for rcu_sched_qs() and rcu_bh_qs().
  * Also irqs are disabled to avoid confusion due to interrupt handlers
@@ -250,7 +150,7 @@ void rcu_bh_qs(void)
 void rcu_check_callbacks(int user)
 {
        RCU_TRACE(check_cpu_stalls());
-       if (user || rcu_is_cpu_rrupt_from_idle())
+       if (user)
                rcu_sched_qs();
        else if (!in_softirq())
                rcu_bh_qs();
@@ -357,6 +257,11 @@ static void __call_rcu(struct rcu_head *head,
        rcp->curtail = &head->next;
        RCU_TRACE(rcp->qlen++);
        local_irq_restore(flags);
+
+       if (unlikely(is_idle_task(current))) {
+               /* force scheduling for rcu_sched_qs() */
+               resched_cpu(0);
+       }
 }
 
 /*
@@ -383,6 +288,8 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
 void __init rcu_init(void)
 {
        open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+       RCU_TRACE(reset_cpu_stall_ticks(&rcu_sched_ctrlblk));
+       RCU_TRACE(reset_cpu_stall_ticks(&rcu_bh_ctrlblk));
 
        rcu_early_boot_tests();
 }