1 files changed, 10 insertions, 103 deletions

diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 0db5649f8817..cc9ceca7bde1 100644
--- 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);
 
@@ -179,23 +89,13 @@ 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
  * invoking call_rcu().
@@ -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();
 }